SAES-J-902

Engineering Standard SAES-J-902

Electrical Systems for Instrumentation

Document Responsibility: Instrumentation Standards Committee

26 March 2020

Contents

Summary of Changes … 2

Scope … 3
Conflicts and Deviations … 3
References … 3
Definitions … 5
General … 8
Conduit and Cable Sealing … 8
Enclosures … 9
Conduit, Conduit Fittings, and Supports … 10
Cable Trays … 11
Connections at Field Instruments and Junction

Boxes … 12 11. Power Supply … 14 12. Signal/Control Wiring … 16 13. Routing … 18 14. Signal Segregation, Separation, and Noise

Reduction … 21 15. Termination … 25 16. Identification … 27 17. Grounding … 28 18. Intrinsically Safe Systems … 31 Document History … 39

Previous Revision: 1 January 2018 Contact: SAHANFA

Next Revision: 26 March 2025 Page 1 of 39

Saudi Aramco: Company General Use

Document Responsibility: Instrumentation Standards Committee Publish Date: 26 March 2020 Next Revision: 26 March 2025

SAES-J-902

Electrical Systems for Instrumentation

Summary of Changes

Paragraph

Change Type (Addition, Modification, Deletion)

Technical Change(s)

Sec 1

Modification

Add Intrinsically Safe (I.S.) systems to the scope of the

documentation.

Sec 3

Sec 4

Sec 5

Sec 6

Modification

Updating references by adding and deleting.

New

Add definitions for the I.S. systems.

Add fireproofing for radioactive instruments.

Add double compression cable gland with two seals.

Add nickel plated brass material for cable gland.

Sec 7 & 9

Modification

Revise maximum copper content to 0.4% for aluminum

Sec 9

New

Mandate fiberglass tray for outdoor offshore

Allow and add requirements for fiberglass cable tray.

installations, outside fire hazardous zone.

Clarify the cable routing methods in the following

sequence options:

Aboveground cable routing avoiding fire hazardous

Sec 13

Modification

zone.

Underground cable routing in fire hazardous zone.

Aboveground routing in fire hazardous zone and meet

all requirements per SAES-B-006 and NEC.

Page 2 of 39

Saudi Aramco: Company General Use

Document Responsibility: Instrumentation Standards Committee Publish Date: 26 March 2020 Next Revision: 26 March 2025

SAES-J-902

Electrical Systems for Instrumentation

Scope

This standard establishes the design criteria for the installation of power and wiring systems for electrical instrumentation. This standard also defines the conditions to be fulfilled to meet Saudi Aramco requirements for intrinsically safe (I.S.) systems. “Intrinsic safety” is a design and construction method that can be applied to electrical and electronic instruments and their interconnection wiring for safe use in a hazardous (classified) location. However, this standard is not intended as a guide for I.S. equipment design.

Conflicts and Deviations

Any conflict between this document and other applicable Mandatory Saudi Aramco Engineering Requirements (MSAERs) shall be addressed to the EK&RD Coordinator. Any deviation from the requirements herein shall follow internal company procedure SAEP-302, Waiver of a Mandatory Saudi Aramco Engineering Requirement.

References

The selection of material and equipment, and the design, construction, maintenance, and repair of equipment and facilities covered by this standard shall comply with the latest edition of the references listed below, unless otherwise noted.

Saudi Aramco References

Saudi Aramco Engineering Procedures

SAEP-302

Waiver of a Mandatory Saudi Aramco Engineering Requirement

Saudi Aramco Engineering Standards

SAES-B-006 SAES-B-008 SAES-B-068 SAES-J-003

SAES-J-510 SAES-J-904 SAES-M-014

SAES-M-015

SAES-P-100 SAES-P-103

Fireproofing for Plants Restrictions to Use of Cellars, Pits, and Trenches Electrical Area Classification Instrumentation and Control Buildings - Basic Design Criteria Process Analyzer Systems Foundation™ fieldbus (FF) Systems Governing Drawings for The Design of 10-WellHead (SSS) Offshore Oil Platform Governing Drawings for the Design of Offshore Gas Platform Basic Power System Design Criteria UPS and DC Systems

Page 3 of 39

Saudi Aramco: Company General Use

Document Responsibility: Instrumentation Standards Committee Publish Date: 26 March 2020 Next Revision: 26 March 2025

SAES-J-902

Electrical Systems for Instrumentation

SAES-P-104 SAES-P-111 SAES-Z-020

Wiring Methods and Materials Grounding Design and Installation of Fiber Optic Cable Systems for Process Control Networks

Saudi Aramco Materials System Specifications

17-SAMSS-516 23-SAMSS-010 34-SAMSS-820 34-SAMSS-913

Uninterruptible Power Supply System Distributed Control Systems Instrument Control Cabinets Instrument and Thermocouple Cable

Saudi Aramco Library Drawings

DC-950043-001 DC-950150-001

Electrical Connections for Field Mounted Instruments Recommended Grounding Scheme for Process Automation System

Industry Codes and Standards

American National Standards Institute

ANSI/ISA TR12.21.01

Use of Fiber Optic Systems in Class I Hazardous (Classified) Locations

American Petroleum Institute

API RP 2218

API RP 14F

Fireproofing Practices in Petroleum and Petrochemical Processing Plants Design, Installation, and Maintenance of Electrical Systems for Fixed and Floating Offshore Petroleum Facilities for Unclassified and Class 1, Division 1 and Division 2 Locations

ASTM International

ASTM E84

Standard Test Method for Surface Burning Characteristics of Building Materials

British Standards Institution

BS 6121-1 BS 62444

Mechanical Cable Glands Cable glands for electrical installations

International Electrotechnical Commission

IEC-60079-14

Explosive Atmospheres – Part 14: Electrical installations design, selection and erection

Page 4 of 39

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Document Responsibility: Instrumentation Standards Committee Publish Date: 26 March 2020 Next Revision: 26 March 2025

SAES-J-902

Electrical Systems for Instrumentation

IEC 60079-15

IEC 60529

Explosive Atmospheres – Part 15: Construction, test and marking of type of protection ‘n’ electrical apparatus Degrees of Protection Provided by Enclosures

National Electrical Manufacturers Association

NEMA ICS 6 NEMA 250

NEMA VE 1 NEMA VE 2

Industrial Control and Systems: Enclosures Enclosures for Electrical Equipment (1000 Volts Maximum) Metal Cable Tray Systems Cable Tray Installation Guidelines

National Fire Protection Association

NFPA 70 NFPA 72

National Electrical Code (NEC) National Fire Alarm Code

Process Industry Practices

PIP PCCEL001

Instrumentation Electrical Design Criteria

Underwriters Laboratories, Inc.

UL 94

UL 568

Standard for Safety Test for Flammability of Plastic Materials for Parts in Devices and Appliances Nonmetallic Cable Tray Systems

The International Society of Automation (ISA)

ISA MC96.1 ISA RP12.6.01

ISA RP12.2.02

ISA TR12.2

Definitions

Temperature Measurement Thermocouples Recommended Practice for Wiring Methods for Hazardous (Classified) Locations Instrumentation Part 1: Intrinsic Safety Recommendations for the Preparation, Content, and Organization of Intrinsic Safety Control Drawings Intrinsically Safe System Assessment Using the Entity Concept

The following list of definitions shall apply to this standard: Associated Apparatus: Apparatus in which the circuits are not necessarily intrinsically safe themselves, but which affect the energy in the intrinsically safe circuits and are relied upon to maintain intrinsic safety. The associated apparatus represents the primary means to limit energy to field devices located in hazardous areas. It often consists of an intrinsic safety barrier or isolator.

Note: Active galvanic isolators are the preferred type of associated apparatus.

Page 5 of 39

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SAES-J-902

Electrical Systems for Instrumentation

Class 1 Circuit: A circuit complying with National Electrical Code (NEC) Article 725, Part II. Class 2 Circuit: A circuit that complies with National Electrical Code (NEC) Article 725, Part III. Class 3 Circuit: A circuit that complies with National Electrical Code (NEC) Article 725, Part III. Control Drawing: A drawing or other documentation provided by the manufacturer of the intrinsically safe or associated apparatus that details the allowed interconnections between the intrinsically safe and associated apparatus. If the intrinsically safe or associated apparatus is investigated under the entity concept, the control drawing shall include all applicable electrical parameters to allow for selection of apparatus for interconnection. Data Link: Any information channel used for connecting data processing equipment to any input, output, display device, or other data processing equipment. Drain Wire: In a cable, the non-insulated wire in intimate contact with a shield to provide for termination of the shield to a ground point. Fault: A defect or electrical breakdown of any component, spacing or insulation that alone or in combination with other faults, may adversely affect the electrical or thermal characteristics of the intrinsically safe circuit. If a defect or breakdown leads to defects or breakdowns in other components, the primary and subsequent defects and breakdowns are considered to be a single fault. Flameproof : Type of protection where the enclosure will withstand an internal explosion of a flammable mixture that has penetrated into the interior, without suffering damage and without causing ignition, through any joints or structural openings in the enclosure of an external explosive gas atmosphere consisting of one or more of the gases or vapors for which it is designed. Also known as an explosion proof. Home-Run Cable: A cable, typically multi-pair/triad, extending between the field junction boxes and marshalling cabinets in control or PIB buildings.

Note: Multi-pair/triad cable between the field junction box and any control cabinets such as RTU, PLC, etc is considered as home-run cable. Intrinsically Safe Apparatus: Apparatus in which all the circuits are intrinsically safe. Intrinsically Safe Circuit: A circuit in which any spark or thermal effect, produced either normally or in specified fault conditions, is incapable, under the test conditions prescribed, of causing ignition of a mixture of flammable or combustible material in air in its most easily ignited concentration. Intrinsically Safe System: An assembly of interconnected intrinsically safe apparatus, associated apparatus, and interconnection cables in which those parts of the system that may be used in hazardous (classified) locations are intrinsically safe circuits. Intrinsic Safety Ground Bus: A grounding system which has a dedicated conductor separate from the power system and which is reliably connected to a ground electrode in accordance with Article 504.50 of the NEC and as specified in the I.S. control drawing.

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Document Responsibility: Instrumentation Standards Committee Publish Date: 26 March 2020 Next Revision: 26 March 2025

SAES-J-902

Electrical Systems for Instrumentation

Severe Corrosive Environments: For the purpose of this standard, severe corrosive environments include:

a. b.

Outdoor offshore locations, covered by API RP 14F Outdoor onshore locations within one kilometer from the shoreline of the Arabian Gulf Outdoor onshore locations within three kilometers from the shoreline of the Red Sea. If part of the facility fence located within the boundary specified in b and c, the complete facility shall be considered as “severe corrosive environments”. Locations where chlorine or other corrosive chemicals are being handled (e.g., sulfur plants, waste water treatment, water treatment, R.O. facilities).

Simple Apparatus: A device which will not generate or store more than 1.5 V, 100 milliamps, and 25 milliwatts, or a passive component that does not dissipate more than 1.3 watts and is compatible with the intrinsic safety of the circuit in which it is used. Examples are switches, thermocouples, light-emitting diodes, and resistance temperature detectors (RTDs). The Entity Concept: Another method of interconnecting equipment is commonly known as the entity concept. This has some unique advantages over systems. Using this concept, a listed associated apparatus and a listed field device, not necessarily manufactured by the same company, may be connected together without obtaining a listing for the specific combination. This allows for much greater flexibility in the field when purchasing equipment. However, this concept requires special attention be paid to the control drawings, not only for the associated apparatus, but also for the field device. The control drawings for each piece of equipment are provided with electrical ratings known as entity parameters, which represent the limits of the equipment, either with respect to the maximum output characteristics, or the maximum allowable input characteristics. These parameters are as follows:

Voc or Uo, this represents the maximum open circuit voltage that may be present at the specified terminals under the most adverse conditions.

Isc or Io, this represents the maximum short circuit current that may be present at the specified terminals under the most adverse conditions.

Ca or Co, this represents the maximum capacitance that may be connected to the specified terminals without invalidating safety.

La or Lo, this represents the maximum inductance that may be connected to the specified terminals without invalidating safety.

Page 7 of 39

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Document Responsibility: Instrumentation Standards Committee Publish Date: 26 March 2020 Next Revision: 26 March 2025

SAES-J-902

Electrical Systems for Instrumentation

5.1

5.2

General

Design and installation of power and wiring systems for instrumentation shall be in accordance with NFPA 70, National Electrical Code (NEC), unless otherwise supplemented by this standard. Foundation Fieldbus wiring systems shall be installed in compliance with SAES-J-904 FOUNDATION™ fieldbus (FF) Systems.

Electrical and electronic equipment in hazardous areas shall meet listing/certification requirements specified in SAES-P-100 and the NEC. The electrical area classification shall meet SAES-B-068.

Intrinsically Safe Systems

5.4.1

5.4.2

Intrinsically safe (I.S.)systems shall only be used in Zone 0 electrically classified areas or when the vendor’s standard product offering is supplied as intrinsically safe. Intrinsically safe systems shall be certified per paragraph Note: Only Zone 0 compliant I.S. systems can be used in Zone 0 locations. Intrinsically safe systems shall be installed in compliance with section 18 of this standard.

Fireproofing in fire hazardous zones shall be in accordance with SAES-B-006.

Note: Radioactive instruments in fire hazardous zone shall be fire-proofed in accordance to API 2218 section 5.1.10.

Fire Alarm systems shall be installed in accordance with NEC Article 760 and NFPA 72.

Cable Ties

5.7.1 All cable ties used in the field shall be nylon coated 316 stainless steel. The cable ties shall have a minimum temperature rating of 80ºC or higher. This is applicable in fastening the cables inside the cable trays both for vertical and horizontal runs.

5.7.2 316 stainless steel cable ties shall be used to secure cable tray covers. 5.7.3 All cable ties used inside of buildings (i.e., control rooms and PIBs) shall be

weather resistant nylon cable ties.

Conduit and Cable Sealing

Conduit and cable sealing shall be installed in accordance with NEC Article 505, except as specified in paragraphs 6.2 and 6.3.

Armored Cable Sealing

Certified flameproof (Type‘d’) cable glands using a compound barrier seal shall be used on all instruments and enclosures located in hazardous areas requiring sealing per the NEC.

Page 8 of 39

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Document Responsibility: Instrumentation Standards Committee Publish Date: 26 March 2020 Next Revision: 26 March 2025

SAES-J-902

Electrical Systems for Instrumentation

Note: A certified flameproof (Type‘d’) non-barrier cable glands is permitted if it is double compression type and has two seals. The outer seal is used for ingress protection and the inner seal is used to seal flame from propagating to outside junction box. The non-barrier cable gland shall meets IEC 60079-14. In order to maintain ingress protection levels and ensure good installation practice, either of the following threads shall be used: 6.2.1 6.2.2

Parallel thread (metric) entry threads into instruments and wiring enclosures, Tapered threads (NPT) of conduit or cable glands shall enter an instrument or wiring enclosure via: 6.2.2.1

The body of the equipment is threaded ensuring 5 full threads are engaged. In the case where NPT threading is not possible, i.e., a junction box, a suitable certified or listed sealing device (e.g., metric-to- NPT adapter) shall be used.

6.2.2.2

As a minimum, all cable glands shall be made of 316 stainless steel or nickel plated brass. Refer to BS 6121-1 and BS-62444 for further information.

Conduit Sealing for Individually Shielded Twisted Pair/Triad Cable

When individually shielded twisted pair cable passes through a conduit seal, it shall be treated as a single conductor and shall be sealed with the outer jacket intact. In addition, the cable end within the enclosure shall be sealed by an approved means.

7.1

7.2

7.3

Enclosures

Enclosures for instruments in outdoor plant non-corrosive areas shall be a minimum of NEMA Type 4 in accordance with NEMA ICS 6 and NEMA 250 or IEC 60529 Type IP 65. Enclosures for instruments in severe corrosive environments shall be a minimum of NEMA Type 4X or IEC 60529 Type IP 66. As a minimum, the instrument enclosures, shall be made of 316 SS or cast copper-free aluminum (0.4% max. copper) and shall be suitable for the areas where they are installed. The electrical connection entry to enclosures should be ½ inch NPT or metric threaded glands, and shall ensure IP/NEMA rating is maintained via a third party certificate. The field junction box in non-corrosive environment shall be single door box NEMA Type 4 or IEC 60529 Type IP 65 and made of cast copper-free aluminum (0.4% max copper) or UV protected non metallic GRP with three side sunshades. For severe corrosive environment in offshore/onshore installations, the field junction box shall be a single door NEMA Type 4X or IEC 60529 Type IP 66 box. The box shall be made of either 316 SS or UV protected GRP with three side sunshades. Construction shall meet the following requirements:

Page 9 of 39

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Document Responsibility: Instrumentation Standards Committee Publish Date: 26 March 2020 Next Revision: 26 March 2025

SAES-J-902

Electrical Systems for Instrumentation

7.3.1

7.3.2 7.3.3

7.3.4

7.3.5 7.3.6 7.3.7 7.3.8 7.3.9 7.3.10

Body, door, fittings, breathers, plugs, and other hardware shall be made from the same material as the box or metallurgical compatible one. The body shall have a smooth-finish. Hinges shall be made from the same material as the box or metallurgical compatible one. For GRP body, exterior hardware including hinges shall be 316SS. Captive clamps shall be made from the same material as the box or metallurgical compatible one. Exception: Captive screws may be used in lieu of captive clamps provided that the screws do not penetrate the door gasket. Keylocks and padlocks are not acceptable. A Data/Print pocket on inside of door. External mounting brackets. Collar studs for mounting inside panel if applicable. Ground stud for terminating A/C safety ground wire. Removable door. Back panels shall be made from the same material as the box or metallurgical compatible one.

All field junction boxes shall be mounted vertically, i.e., the door shall open from left- to-right or from right-to-left. Instrument enclosures and junction boxes having an internal volume exceeding 2,000 cm³ (122 in³) shall be provided with Type 300 Series stainless steel certified breather and drain fittings, or a combination breather and drain fitting.. Instrument junction boxes shall be properly sized to allow for safe and easy access for maintenance.

Conduit, Conduit Fittings, and Supports

Conduit, conduit installation, fittings, and supports shall comply with SAES-P-104, Wiring Methods and Materials. Exception: Where conduit sealing is required, paragraphs 6.1 and 6.3 of this standard shall be followed. In outdoor installations, conduit bodies and fittings shall have threaded cover openings. Exception: For non-circular conduit fittings (such as L-shaped bodies (LB), wire pulling fittings, etc.), screwed or bolted covers are acceptable. Snaptight covers or covers with internal holding levers are not acceptable. A conduit outlet box shall be installed within 460 mm (18 in) of the field device. The cable to the instrument shall be looped one or more times within this fitting; the sizing of the conduit outlet box shall take into account the bending radius of the cable.

Note: The new transmitters and digital valve controllers have very small connection heads compared to previous models. Therefore, a conduit outlet box is being mandated within 18” of the device to allow for a spare loop of cable. This can potentially prevent maintenance from having to re-pull cable if the cable end has been damaged.

Page 10 of 39

7.4

7.5

7.6

8.1

8.2

8.3

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SAES-J-902

Electrical Systems for Instrumentation

8.4

Flexible conduit shall be used at the instrument end of the conduit to provide isolation from vibration, protection against thermal expansion of the rigid conduit systems and for ease of maintenance. 8.4.1

8.4.2

8.4.3

For Class I, Zone 1 hazardous locations, flexible fittings listed for the area shall be used. For Class I, Zone 2 locations and unclassified areas, the flexible conduit shall be listed as Liquidtight Flexible Metal Conduit (LFMC). The LFMC shall have a sunlight resistant cover which resists oil and chemical breakdown and shall be rated for temperatures ≥ 80ºC. Where practically possible, the length of the flexible conduits should not exceed 1,000 mm (≈ 39 in). Exception: Flexible metal conduits installed on rotating equipment (i.e., temperature, vibration, etc.) may be 1,830 mm (≈ 72 in) long. The bends (curves) shall not exceed the equivalent of four quarter bends (360 degrees total) throughout the LFMC entire length. In addition, the radius of the curves shall be per NFPA 70, Chapter 9.

8.5 Metallic conduit shall be grounded as required in SAES-P-111.

9.1

9.2

9.3

9.4

9.5

9.6 9.7

Cable Trays

Cable tray specification shall be per NEMA VE 1. The tray installation shall be per this standard, NEMA VE 2, and SAES-P-104. Homerun cable trays shall be of the ladder type, i.e., two longitudinal side rails connected by individual transverse members (rungs). The distance between consecutive rungs shall not exceed 229 mm (9 in). Ladder cable tray material shall be copper-free aluminum (aluminum with a maximum of 0.4% copper) or fiberglass. For outdoor offshore applications, outside fire hazardous zone, cable tray material shall be fiberglass. For indoor air conditioned areas galvanized carbon steel is allowed. These requirements are also applicable to cable trays supporting multi-pair/triad instrumentation cables inside control buildings and/or substations. Fiberglass cable tray shall be designed, manufactured, rated, supported and tested in accordance with UL 568. Fiberglass cable trays shall be fire retardant and sunlight (ultraviolet radiation) resistant. The fiberglass cable trays shall be certified per ASTM E84 Class 1 and/or listed per UL 94 V-O. The cable tray system shall be installed with the manufacturers standard fittings, clamps, hangers, brackets, splice plates, reducer plates, blind ends, connectors, and grounding straps. All fasteners (i.e., nuts, bolts, washers, etc.) used to connect and assemble the cable tray system shall be 304 SS. In severe corrosive environments, 316 SS fasteners shall be used. Cable Trays shall be grounded as required in SAES-P-111. In new grass root projects, cable trays extending between the process area and the control room or process interface building, or trays installed beneath raised computer

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SAES-J-902

Electrical Systems for Instrumentation

9.8 9.9

floors, in control rooms or PIB shall be sized for a minimum of 20% spare space for future expansions. This spare capacity is in addition to the installed 20% spare cabling. The overall cable fill with all spare requirements shall not exceed tray fill requirement stipulated in paragraph 9.8. Cable tray fill area shall comply with NEC Article 392. Cable tray supporting armored cables extending between field instruments and junction boxes (i.e. branch cable) shall be ventilated bottom, channel or trough cable tray. The cable tray shall be designed, manufactured, and marked in accordance with NEMA VE 1. The working load of the cable tray shall consist of the weight of the cables, plus a concentrated static load of 45 kg at the center of the span. The static load can be converted to an equivalent uniform load using the formula in NEMA VE 1. The overall working weight shall not exceed the rated load capacity of the cable tray as defined in NEMA VE 1. In addition to the requirements in paragraphs 9.1 and 9.6, the cable tray system shall meet the following: 9.9.1

9.9.2

9.9.3

9.9.4 9.9.5

9.9.6

9.9.7

9.9.8

The branch cable tray material shall be copper-free aluminum (aluminum with a maximum of 0.4% copper) or fiberglass. The branch cable tray width should be 76, 102, or 152 mm (≈ 3, 4, or 6 in) with a minimum loading depth of 32 mm (≈1-¼ in). The branch cable tray system shall be installed with the manufacturers standard fittings, clamps, hangers, brackets, splice plates, reducer plates, blind ends, connectors, and grounding straps. The branch cable tray system shall be installed with flanged covers. The ventilated straight sections should have slots (approximately 3/16” x ½”) to facilitate the use of cable ties to secure the cable(s). The slots should repeat every 305–457 mm (≈12–18 in). The ventilated straight sections should have splice holes, repeating every 305–457 mm (≈12–18 in) to simplify field modifications. All fasteners (i.e., nuts, bolts, washers, etc.) used to connect and assemble the branch cable tray system shall be 304 SS. In severe corrosive environments, 316 SS fasteners shall be used. The cable tray system shall be free from burrs or other sharp projections that could cause damage to the cable jacket during installation.

Connections at Field Instruments and Junction Boxes

Connections at Field Instruments

10.1.1

All connections at the field instrument shall be made on screw type terminal blocks or pressure-loaded (screw-less) terminal blocks. Wire nuts and spring type terminals shall not be used. Instruments with integral terminal blocks shall be connected directly to the field cable.

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SAES-J-902

Electrical Systems for Instrumentation

10.1.2

10.1.3

If the instrument is fitted with factory sealed fly leads then they shall be connected to a screw type terminal block or pressure-loaded (screw-less) terminal blocks installed in a GUA conduit fitting. A typical installation arrangement is shown in Library Drawing DC-950043-001, Electrical Connections for Field Mounted Instruments. For armored cable installation, the armored cables shall be terminated at both ends using cable glands per paragraph 6.2. The support and routing of the armored cable to the junction box shall be per paragraph 13.1.1.2. The outer jacket of shielded twisted single pair/triad cables shall be left intact up to the point of termination. Drain wires and mylar shields on shielded cables shall be cut and insulated with heat shrink sleeve at the field instrument unless otherwise specified by the instrument manufacturer. For armored cables, the “outer jacket” is the jacket covering the pair or triad; not the jacket covering the armor.

Connections at Field Junction Boxes

10.2.1

10.2.2

10.2.3

10.2.4

10.2.5 10.2.6

10.2.7

10.2.8

All instrument wiring shall be routed to field junction boxes. Conduit and cable entries to field junction boxes shall be through the bottom. Exception: Conduit top side entry into a junction box is allowable provided that a drain seal is installed on the conduit within 457 mm (18 in) of the junction box. All unused entry ports shall be fitted with approved plugs. Conduit entries shall be through gasketed hubs with grounding provision, except in explosion-proof installations where the connection shall be through threaded connections. Armored cable entry to the junction boxes shall be per paragraph 6.2. In severe corrosive environments, cable glands shall be protected against corrosion, either by a heat shrink sleeve, anti-corrosion tape or PVC shroud. Gasket materials shall be oil resistant. All connections and entries shall comply with the electrical area classification. Low point conduit drains shall be provided as needed. Twisted, multi-pair/triad cables shall be cut to the appropriate length to minimize looping and flexing of the cable within the junction box. For twisted shielded single pair/triad cables the outer jacket shall be left intact up to the point-of-termination, approximately 76–101 mm (3–4 in) from terminal blocks). The shield drain wire shall be insulated from jacket end to terminal. Approximately, one inch of heat shrink tubing shall be applied over the jacket end. For armored cables, the “outer jacket” is the jacket covering the pair or triad; not the jacket covering the armor. For individually shielded twisted multi-pair/triad cables each pair/triad shall be heat shrink sleeve insulated from the cable-jacket-end up to the point-of- termination to keep the foil shielding intact and free from accidental

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SAES-J-902

Electrical Systems for Instrumentation

grounds. The shield drain wire shall be insulated from foil end to terminal. Approximately, two inches of heat shrink tubing shall be applied over the jacket end. Terminal blocks used in junction boxes shall be per paragraph 15.2. The terminals shall be mounted on vertical DIN rails (i.e., horizontal DIN rails are not recommended).

Note: This paragraph is specifying vertical DIN rails in ‘field junction boxes’. It is not intended to apply to ancillary termination boxes, e.g., smart ZV control stations, GUA fittings, etc. The DIN rail shall only be mounted on the inside panel (back-pane) of the junction box. Twenty percent (20%) un-used DIN rail length shall be provided in field junction boxes.

10.2.9 10.2.10

10.2.11

10.2.12

Power Supply

Supply Voltages

11.1.1 Where instrument-circuit power distribution panels are used, each panel

11.1.2

11.1.3

shall be dedicated to a single voltage level. These panels shall not provide power to non-instrumentation circuits. Distribution panels shall be furnished with a minimum of 20% spare circuit breakers. Redundant power supplies feeding process automation systems, emergency shutdown systems, metering systems, auxiliary systems or field instrumentation shall be fed from separate distribution panels. Power wiring for field instruments, two-wire analog transmission loops, field switch contacts, etc., shall be individually fused and provided with a means of disconnecting the power without disturbing terminated wiring (e.g., knife-switch-type terminal blocks). Visual indication of a blown fuse condition shall be provided. Exceptions:

Wiring connected to I/O modules or to interfaces containing individual current- limiting circuit protection does not require fuses.
Low level signal wiring connected directly to I/O does not require fuses. Low level signals are defined as Millivolt, Microamp, Pulse, and Frequency Signals under 1 Volt.

Note: Fuse application, location, and amperage ratings must be properly sized and coordinated, taking into account the maximum expected load at the maximum operating temperature of the indoor cabinet (50°C). Equipment shall be suitable for the supply voltages shown in Table 1.

Table 1 - Supply Voltages

System/Device

Nominal

Supply Voltage Tolerance

NEC Class

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SAES-J-902

Electrical Systems for Instrumentation

Annunciator Power

Shutdown and isolation system power

Field switch contacts

24 VDC 125 VDC 120 VAC, 60 ±2 Hz 230 VAC, 60 ±2 Hz

21 - 28 VDC 113 - 137 VDC 110 - 126 VAC 218 - 242 VAC

21 - 28 VDC 113 - 137 VDC 110 -126 VAC 218 - 242 VAC

21 - 28 VDC 113 - 137 VDC 110 - 126 VAC 218 - 242 VAC

1 or 2 1 or 3 1 or 3 1 or 3

Analog signal (loop power)

24 VDC (4-20 mA)

21 - 28 VDC

1 or 2

Instrumentation power

24 VDC 120 VAC, 60 ±2 Hz 230 VAC, 60 ±2 Hz

21 - 28 VDC 110 - 126 VAC 218 - 242 VAC

1 or 2 1 or 3 1 or 3

11.1.4 Where multiple online DC power supplies are connected to a single power

bus, diode auctioneering shall be used to ensure bump less transfer in the event of a single power supply failure. Where multiple DC power supplies are an integral part of a manufacturer’s standard product, the manufacturer’s standard method of load sharing shall apply. For supplies to DC instrument loads, voltage stabilization shall be provided to maintain the output voltage within tolerable limits of the loads served.

11.1.5

Backup Supply Systems

11.2.1

UPS Systems 11.2.1.1 All process instrumentation, PLCs, burner management systems,

MOV control circuits and master stations, distributed control systems, terminal management systems, vibration monitoring systems, tank gauging systems, metering systems, stand-alone controllers, computational devices, annunciators, gas detection/safety systems, SCADA systems, and emergency shutdown (ESD) systems shall be powered by UPS system. Process analyzers and emission monitoring devices shall be powered in accordance to SAES-J-510.

Note: Backup supply for fire system shall be per NFPA 72 11.2.1.2 Uninterruptible power supply (UPS) systems shall be designed and installed in accordance with SAES-P-103 and 17-SAMSS- 516.

11.2.1.3 UPS power and utility power shall not share the same cable or be

routed in the same conduit or cable tray.

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11.2.2

11.2.3

11.2.4

Redundant UPS System UPS systems powering critical instrumentation shall consist of redundant UPS units. Critical instrument systems are defined as systems which, upon loss of their supply power, would cause: 1) process failure that is not fail-safe, 2) area or plant shutdowns, 3) loss of custody transfer metering or accounting systems, or 4) other adverse facility operating scenarios. Such systems shall include, but not be limited to: ESD; HIPPS; VMS; process heater safety; gas detection systems; compressor control; boiler burner management; process monitoring and control; and custody transfer metering systems. Exception: Simplex UPS systems may be used on non-critical process and service facilities such as Bulk Plants and GOSPs. UPS Batteries UPS battery requirements, such as capacity determination, installation and charging systems, are detailed in SAES-P-103. The time during which the battery bank shall supply power to the instrumentation system shall depend on the application, but not be less than 30 minutes. Backup Supply for Instruments with Volatile Memory Backup power supply shall be required for instrumentation systems containing volatile memory. For all such systems, the manufacturers’ recommendations shall be followed.

Signal/Control Wiring

General

12.1.1

12.1.2

Splices are not permitted in wiring. When wiring must be extended, connections shall be made via terminal blocks in a junction box installed aboveground. Twist-on wire nut connectors shall not be used for making any electrical instrumentation terminations or wiring connections.

Cable Types

Cables used for instrumentation signals shall be selected per Table 2. For detailed cable construction, refer to 34-SAMSS-913.

Table 2 - Wire and Cable Minimum Requirements for Instrument Circuits

A. NEC Article 725 Class 1 Circuits (Notes 1, 2, 7, 8)

Instrument Circuit Type

Circuit Example

Field Instrument To Junction Box

Field Junction Box To Marshalling Cabinet

120/230 VAC or 125 VDC

Switches, Solenoids, Relays, Limit switches

16 AWG, 600 V, single twisted pair, Type TC cable (Note-7)

ARMORED:

16 AWG,600 V, single twisted pair, TYPE MC or equivalent

18 AWG, 600 V, twisted Overall shield multi-pair cable, type TC

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B. NEC Article 725 Class-2&3 Circuits, Conduits & Cable Tray Installations (Notes 1, 2, 3, 7, 8)

Instrument Circuit Type

Circuit Example

Field Instrument To Junction Box

Field Junction Box To Marshalling Cabinet

24 VDC or less Discrete signals

Solenoids, Alarms, Switches, Relays, limit switched, Secondary Motor Control

Analog Signals Frequency, Pulse, or Transmitter Digital Communication

4-20 mA DC, RTDs, Weigh Cells

Speed, Vibration, Turbine Meter, Smart digital Transmitter

16 AWG, 300 V PLTC/ITC, single twisted pair or triad cable

ARMORED:

16 AWG, 300 V SWA, PLTC/ITC, twisted single pair or triad cable

16 AWG, 300 V PLTC/ITC, single twisted, shielded pair or triad cable

ARMORED:

16 AWG,300 V SWA, PLTC/ITC single twisted, shielded pair or triad cable

16 AWG, 300 V PLTC/ITC, single twisted, shielded, thermocouple extension pair cable

18 AWG, 300 V PLTC/ITC Twisted, Overall shield Multi- Pairs or Triads

18 AWG, 300 V PLTC/ITC Twisted, Individually Shielded Multi-Pairs or Triads

18 AWG, 300 V PLTC/ITC, Twisted, Individually Shielded, thermocouple extension multi-pair cable

Thermocouple Measurement

Thermocouples

ARMORED:

16 AWG, 300 V PLTC/ITC, SWA, single twisted, shielded, thermocouple extension pair cable

Data Links

EIA-422A Data Links, High Speed Communication networks

Follow System Manufacturer’s Recommendation (Note-6)

Follow System Manufacturer’s Recommendation

Notes:

Cables installed in Class -1, Zone 1 (Class -1, Div.-1) shall be listed as suitable for that classified area.

In addition, cables used in other classified areas shall meet the requirements outlined in NFPA 70 (NEC), Articles 501-505.

The minimum size for multi-pair/triad cable should be 18 AWG. The minimum wire size for single pair cable shall be 16 AWG. A larger wire size up to 12 AWG may be considered to overcome potential voltage drops. The maximum voltage drop shall not exceed 5% for 120 V AC wiring to solenoid valves, relays, and other electro-mechanical devices. For electro-mechanical DC loads (such as solenoid valves and relays), the voltage drop shall not exceed 10%. For other DC loads, the calculated voltage at the device shall be higher than its minimum operating voltage by 25%.The load functionality at the supplied voltage shall be also confirmed by the manufacturer.

Type ITC cable shall not be installed on either non-power limited circuits or powered limited circuits operating at more than 150 volts or more than 5 amperes.

For control and marshalling cabinet wiring, refer to 34-SAMSS-820.

Maximum separation between redundant data links must be obtained within the operating plant. The use of a single cable tray or conduit for primary and backup data links is not acceptable. Refer to paragraph 12.3
Protection against reverse EMF shall be provided for inductive loads such as relays, solenoids, etc. This may be accomplished by installing a diode across the coil for DC loads or a metal oxide varistor (MOV) across the coil for AC inductive loads.

If a discrete loop length exceeds 305 meters (≈1,000 feet), 120/230 VAC signal shall not be used due to potential capacitive or inductive coupling. In such cases, DC voltage shall be used.

Cables used in Class 1, Class 2 and Class 3 circuits shall meet the requirements of Article 725 of the

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National Electrical Code (NEC). Class 1 circuit wiring is preferred when the circuit class is not identified.

Special Cables

Data Links Copper data link cables shall be specified per system manufacturers’ recommendations. In plant fiber optic data link cables shall be specified and installed per SAES-Z-020. Data link cables shall not be routed in the same conduit duct, or tray with other instrument cables. Exception: Fiber Optic data link Cables may be routed with other instrumentation cables – in existing trays or ducts. Fiber Optic cables installed in trays shall be routed in PVC conduit and shall meet ANSI/ISA TR12.21.01 if installed in classified areas.

Color Coding

Power and signal wiring shall be color coded as follows:

AC Supply

DC Supply

Signal Pair

Signal Triad

Thermocouple

Phase Neutral Ground Positive Negative Positive Negative Positive Negative Third Wire Positive Negative

Black White Green with yellow tracer Red or red sleeve over any color except green Black or black sleeve over any color except green Black White Black White Red Per ISA MC96.1 Per ISA MC96.1

Routing

Instrumentation and control cables and data highways in the field may be routed either aboveground, underground or a combination of both as detailed in this standard. Exception: The routing for offshore shall be per SAES-M-014 and SAES-M-015

Aboveground Routing

Aboveground instrumentation cables may be run on a cable tray or in a conduit as detailed below. Aboveground is the preferred routing method within a process facility. Cable, conduit and cable tray aboveground in fire hazardous zones shall meet fireproofing requirements as specified in SAES-B-006 and NEC for hazardous requirements. 13.1.1

Instrument to Field Junction Box Cable between field instruments and junction box shall be routed above ground utilizing one of the following options:

13.1.1.1 Cable and Conduit

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Single twisted pair/triad cables, per Table 2, shall be installed in steel conduits from the field instruments to the field junction boxes. Low- point drains and breathers shall be provided as required on all conduits. Conduit installation shall be per Section 8.

13.1.1.2 Armored Cable and Tray

a) Armored instrumentation cable shall be routed on a cable tray

per paragraph 9.9. Single pair cables (armored or non-armored) shall not be routed on ladder cable trays.

b) The armored cable shall be routed independently of existing

overhead tray systems used for “home-run” cables.

c) The unsupported end of the cable at the instrument shall be

looped; this loop shall take into account the bending radius of the cable. The unsupported length of cable at the instrument shall be the minimum length required to provide the service loop. Note: This unsupported loop in the armored cable is required to provide sufficient slack for cable gland make-up and for easy removal of the cable from the device for future instrument change- out.

13.1.2

Field Junction Box to Control Room Marshalling Cabinet

13.1.2.1 Cables between field junction boxes and marshalling cabinets may be routed in conduits, on trays, or direct buried. For direct burial, the trench shall be constructed per SAES-P-104. Twisted, multi- pair/triad cables per Table 2 shall be used for all homerun cables. The use of armored cables for homerun application is not recommended. However, if they are used, the cables shall be terminated using glands per paragraph 6.2 at both ends. In addition, the armor shall be grounded at both ends. 13.1.2.2 All signal wiring from field cables shall terminate in dedicated

‘marshalling cabinets.’ Marshalling cabinets shall comply with 34- SAMSS-820, Instrument Control Cabinets.

Exceptions:

Wiring for millivolt, microamp, pulse, and frequency signals under one Volt such as thermocouples, vibration elements, load cells, thermistor elements, and transmitters with pulse outputs may be directly connected to the I/O unless otherwise specified.
In outdoor applications where the number of loops is relatively small such as in the case of onshore well sites, half- height marshalling cabinet that are rack mounted may be used.

13.1.2.3 Marshalling cabinets may contain different signal types as long as

they are of the same level and segregated in dedicated terminal blocks within the same enclosure.

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Note: This paragraph is to allow for reducing marshalling cabinet numbers by combining signals of the same level in separate terminal blocks. For example, 24V DC digital and analog signals may be combined in the same cabinet.

13.1.2.4 Marshalling cabinet dedicated for Foundation fieldbus systems may contain FF power supplies, bulk power supplies, and other active components.

13.1.2.5 Each cable or group of cables leaving a specific junction box and carrying similar signals shall contain a minimum of 20% spare of the used pairs or triads.

13.1.2.6 All spare pairs/triads of a multi-pair/triad cable shall be

terminated at both the field junction box and the marshalling cabinet. Drain wires for spare shielded pairs/triads shall also be individually terminated at these locations.

13.1.2.7 Cables entering the marshalling cabinet shall be cut to the

appropriate lengths. Coiling extra cable length or spare pairs/triads beneath the marshalling cabinet is not acceptable. Where practically possible, the homerun cables should be terminated on the left side of the terminal strip. Exception: For wiring directly connected to the I/O, per the exception item in paragraph 13.1.2.2, the spare pairs/triads may be neatly coiled and taped beneath the cabinet.

13.1.2.8 Cable entry into control buildings and similar buildings in

hydrocarbon processing plants shall utilize certified Multi Cable Transit (MCT) or bottom entry per relevant Safety and Security directives. For bottom entry, cable entries shall be in accordance with SAES-P-104.

13.1.2.9 Emergency shutdown system (ESD) wiring shall have dedicated

cabling, junction boxes and marshalling cabinets. Exception: For offshore platforms only, ESD system wiring may be terminated in the same junction box as general instrumentation wiring provided that the signals are of the same type. ESD and non-ESD terminals shall be segregated within the junction box and shall be clearly identified.

13.1.2.10 Wiring for intrinsically safe (I.S.) systems shall be segregated

and installed in dedicated conduit or cable tray and terminated in dedicated junction boxes.

13.1.2.11 Instrument signals of the same type per Section 14 may be

terminated in the same junction box and marshalling cabinet. Each signal type shall be located in separate terminal blocks and shall be clearly marked.

Note: This paragraph is to allow for reducing junction boxes and marshalling cabinets by combining signals of the same level in

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separate terminal blocks. For example, 24V DC digital and analog signals maybe combined in the same junction box.

13.1.3 Marshalling Cabinet to Control Room Instrumentation and Control Systems 13.1.3.1 Cables connecting marshalling cabinet terminals to control room

instrumentation and control systems shall conform to the requirements of paragraph 13.1.2, above. Pre-assembled cables with plug-in type connectors at the system cabinet end and loose wires at the marshalling cabinet end may be used for interconnections. Wiring lists identifying pin connections shall be required for each pre-assembled cable.

13.1.3.2 Wiring requirements for distributed control systems (DCS) are

detailed in 23-SAMSS-010.

Underground

13.2.1

13.2.2

13.2.3

For home-run cables, direct burial is allowed and shall be in accordance with SAES-P-104, Wiring Methods and Materials, and paragraph 13.1.2.1 of this standard. Branch cables can be installed underground for fire hazardous zone, locations where there is no existing overhead rack or where the aboveground installation will impose challenges to traffic. Cables for underground installation shall comply with direct burial requirements.

Under Raised Floors

13.3.1

Instrumentation cables installed beneath raised computer floors in control rooms shall be placed in ladder, trough or solid bottom cable tray. Segregation and separation of the cabling shall be in accordance with Section 14.

13.3.2 Where cable tray is used beneath raised computer floors in control rooms, it

13.3.3

shall be sized per section 9. Cable trays beneath raised floor shall be adequately identified using suitable permanent tag plates. These tag plates shall be installed at each end, tee connection and at around 3,000 mm (≈ 118 in) intervals. The tag plates shall be located so that it is clearly visible. The tag plates shall contain, as a minimum, the noise susceptibility level of the circuits enclosed (per paragraph 14.1) source, and the destination.

Signal Segregation, Separation, and Noise Reduction

Signal Segregation

14.1.1

Signal wiring (instrumentation cable) shall be categorized with noise susceptibility levels (NSL) of ‘1’ or ‘2.’

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14.1.1.1 Level 1 – High to Medium Susceptibility: Analog signals of less

Foundation Fieldbus 4-20 mA and 4-20 mA with HART

than 50 V and discrete instrument signals of less than 30 V. Signal Types a) b) c) RTD d) Thermocouple e) Millivolt/Pulse f) Discrete input & output signals, e.g., pressure switches, valve position limit switches, indicating lights, relays, solenoids, etc.

g) All wiring connected to components associated with sensitive analog hardware (e.g., strain gauge)

h) Copper data links (RS-232 or 485)

14.1.1.2 Level 2 – Low Susceptibility: Switching signals greater than 30

V, analog signals greater than 50 V, and 120-240 AC feeders less than 20 amps. Signal Types a) Discrete input & output DC signals, e.g., pressure switches, valve position limit switches, indicating lights, relays, solenoids, etc.

b) Discrete input & output AC signals, e.g., pressure switches, valve position limit switches, indicating lights, relays, solenoids, etc. 120-240 AC feeders of less than 20 amps.

14.1.1.3 Level 3 – Power: AC and DC buses of 0-1,000 V with currents of

20-800 amps.

Commentary Note:

Level 3 – Power: is shown for the spacing requirements between ‘instrumentation cable’ and ‘electrical cable’. 14.1.2 Multi-pair/triad cable shall not be used to route more than one signal level.

In addition, junction boxes, marshalling cabinets and cable trays shall be segregated based on signal level (e.g., Signal type with the same NSL may be combined in junction boxes provided each type is segregated within the same junction box and clearly identified). Each signal type may be mixed with other signals within the same multi-pair cable, provided they are of the same level, and that the multi-pair cable has individually shielded pairs Cables with the same noise susceptibility level may be grouped in trays and conduit (e.g., all level-1 cables may be routed in one cable tray).

14.1.3

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Exception: RS-232/485 and other copper communication cables (other than FF) shall be routed in dedicated conduits and trays for functional segregation purposes.

Signal Separation

14.2.1

14.2.2

14.2.3

Tray Spacing: Table 3 indicates the minimum distance in millimeters between the top of one tray and the bottom of the tray above, or between the sides of adjacent trays. This also applies to the distance between trays and power equipment of less than 100 kVA. Tray-Conduit Spacing: Table 4 indicates the minimum distance in millimeters between trays and steel conduits. Conduit Spacing: Table 5 indicates the minimum distance in millimeters between the outside surfaces of parallel steel conduits. This also applies to the distance between steel conduits and power equipment of less than 100 kVA.

14.2.4 When routing instrumentation and control signal cabling (level 1 or 2) near sources of strong electromagnetic fields, such as large transformers, motors and generators, defined for purposes of this standard as greater than 100 kVA, a minimum spacing of 1,500 mm (≈59 in) shall be maintained between the cables and the devices. If a steel conduit is used, the distance may be reduced to 750 mm (29.5 in). For direct buried cable, or cables in PVC conduits, cable spacing shall be as shown in Table 3.

14.2.5

14.2.6 When entering terminal equipment (e.g., motor control center) and the

spacing listed in tables 3, 4, or 5 cannot be maintained, parallel runs shall not exceed 5 ft in the overall run.

14.2.7 Minimum separation requirements between various instrumentation cables and fiber optic data link cables shall be per the manufacturer’s recommendation.

14.2.8 When routing Instrumentation cables (level 1 & level 2) near power cables

carrying higher loads than the limits specified in level 3, the separation distances shall be 1,000 mm (39.4 in) as a minimum. If the routing is to be done through a steel conduit, or crossed at 90 degrees, the minimum separation distance shall not be less than 500 mm (19.7 in). Exception: For offshore, electrical installation shall be per SAES-M-14 , SAES-M- 15 , and the installation of solid fixed metallic barriers between instrumentation and power cables. Power cables and instrumentation cables shall cross at right angles (90 degrees) while maintaining the required separation distances per the tables below. If maintaining the required separation distances is not feasible, a grounded metal barrier shall be placed between unlike levels at the crossover point.

14.2.9

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14.2.10

If the spacing shown in Tables 3, 4 and 5 is impossible to maintain, parallel runs shall be minimized, and runs shall not be parallel to each other for a distance greater than 5 ft (1.5 m).

Table 3 - Tray Spacing, millimeters (inches)

Noise Susceptibility Level

0 (0)

150 (6)

650 (26)

150 (6)

0 (0)

200 (8)

650 (26)

200 (8)

0 (0)

Table 4 - Tray-Conduit Spacing, millimeters (inches)

Noise Susceptibility Level

0 (0)

100 (4)

450 (18)

100 (4)

0 (0)

150 (6)

450 (18)

150 (6)

0 (0)

Table 5 - Conduit Spacing, millimeters (inches)

Noise Susceptibility Level

0 (0)

75 (3)

300 (12)

75 (3)

0 (0)

150 (6)

300 (12)

150 (6)

0 (0)

Noise and Signal Interference Reduction

14.3.1

14.3.2

Noise Signal wiring shall be installed in a manner that will minimize unwanted and unnecessary distortion of the signal. Unwanted noise are imposed on an electric signal transmission system by inductive, capacitive or direct coupling with other circuits by leakage current paths, or ground current loops. In addition, utilizing common return lead for more than one circuit shall be avoided to minimize noise. Twisting and shielding of instrumentation wiring shall also be used as detailed below to minimize the impact of noise on instrumentation signals. Shielding

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14.3.2.1 Shielded cables shall be used as required in Table 2 to reduce

electromagnetic noise. The shield shall be grounded at one point only, typically at the marshalling cabinet in the control room or process interface building. Exception: Shield for grounded thermocouple shall be grounded in the field, at the thermocouple end.

14.3.2.2 Cable shields must have a single, continuous path to ground. Special grounding terminals in intimate contact with the DIN Rail, jumper bars or preformed jumper combs designed for the selected terminal blocks shall be used to consolidate shield drain wires for connection to ground. Ground loops and floating shields shall be avoided. Shield drain wires shall not be daisy- chained to the ground connection.

14.3.2.5

14.3.2.3 Shield drain wires of single pair/triad cables shall be terminated in junction boxes as specified in paragraph 10.2.7. 14.3.2.4 Shields of twisted and individually shielded multi-pair/triad cables shall be terminated in junction boxes as specified in paragraph 10.2.8. In installations where there is a transition from multi-pair or multi-triad cables to individual pairs/triads for field device connection in a junction box, the respective shield drain wires shall be joined via terminal strip and shall not make electrical contact with the junction box or any other circuit. Using push-on type connectors or sandwiched shield bars for shield drain wire connection is not acceptable.

14.3.2.6 The shield drain wire on the ungrounded end of the cable shall be cut and insulated with a heat shrink sleeve to prevent unintentional grounding.

14.3.2.7 Except for coaxial cables, instrument cable shields shall never be

used or considered as signal conductors.

14.3.3

Twisting Twisted pairs/triads shall be used as required in Table 2 to reduce electromagnetic noise.

Termination

Methods

15.1.1

The termination shall be channel (rail) mounted, strip-type terminal blocks, with tubular box clamp connector, and compression bar or yoke, as detailed in paragraph 15.2.

15.1.2 When screw-type terminals are provided on field instruments or other

electrical devices, solderless crimp/compression connectors shall be used for

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connecting stranded copper conductors. Screw-type terminals are defined as those in which the termination method involves the direct compression of the conductor by the underside of the screw head, and which do not contain the conductor within a clamp or yoke. Insulated ring lugs or locking fork connectors, specifically designed to hold the connector on the terminal in the event of loosening of the terminal screw, shall be used on all such connections. Exposed electrical connections at signal lamps and pushbuttons shall be completely shrouded by removable, insulating covers. Pressure-loaded (screw-less type) terminals are acceptable.

15.1.3

Terminal Blocks

15.2.1

15.2.2

15.2.3

Terminal blocks shall be channel (rail) mounted, strip type, with tubular box clamp connector and compression bar or yoke for wire termination. As a minimum, the thickness of the terminals shall be 5 mm or higher. Multi- deck and spring type terminal blocks are not acceptable. Terminals and terminal block accessories (e.g., DIN rail mounting brackets for electrical insulation, busbar support blocks, end brackets, etc.) shall be fire retardant in accordance with UL 94, V0. Terminals and accessories shall be made of halogen free, high strength material such as polyamide, or equivalent materials. Brittle materials such as melamine shall not be used. Fused terminals shall be equipped with blown fuse visual indication. The disconnect levers for fused terminals and knife- switch terminals shall be hinged.

15.2.4 Wires terminated on these terminal blocks shall not have the bare ends

coated with or dipped in solder (“tinned”). However, termination of wiring that has individual strands of the copper conductor tinned during manufacture (typical of shield drain wires or for corrosion protection) is acceptable. Direct termination of the bare wire end is acceptable. No more than two bare wire ends shall be connected to each side of a single terminal block. The use of crimp-on ferrules for this type of termination shall follow manufacturer’s guidelines. Ferrules shall be provided with plastic insulating collars. Two-wire ferrules are acceptable. However, the use of ferrules to daisy chain is not acceptable. Only one ferrule shall be connected to each side of a single terminal block.

15.2.5

Terminal Strip Assemblies

15.3.1

Terminal strip spacing shall allow ample room for plastic wire ducts and permit training and lacing of cables, and fanning of individual wires to termination points. Each terminal strip shall be labeled above or below with the terminal strip number, as shown on wiring diagrams.

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15.3.2

15.3.3

15.3.4

Terminals for similar (AC or DC) current service shall be grouped together and physically separated from terminals for different service by means of dividers, separate mounting rails or separate enclosures. Terminals for 120 VDC and 120/230 VAC power for field contacts shall be segregated from other systems. Terminal strips for ESD wiring shall be completely separate from all other wiring including power, control, and instrumentation.

Wire Ducts and Gutters

15.4.1

Plastic wire ducts with removable covers shall be installed in control panels and marshalling cabinets as required to provide a means of routing and organizing wiring between terminal blocks and instrument racks or panels. A minimum of 50 mm (≈ 2 in) shall be maintained between the duct and terminal strips to permit wire markers to be completely presented without being obscured by the duct. Where space limitations preclude the use of plastic wire ducts, wiring shall be neatly loomed and secured with plastic spiral wrapping or tie-wraps and anchors.

15.4.2 Wire ducts for ESD wiring shall not contain any other types of wiring.

Identification

Wire Tagging

16.1.1

All wiring shall be tagged at each end. Each wire tag shall have two labels. The first label (closest to the end of the wire) shall identify the terminal number to which the wire is physically connected. The other label shall be the terminal number of the connection of the opposite end of the wire.

Note: This paragraph is specifying the source and destination information to be imprinted on one (1) heat shrink sleeve. Sometimes, the term ‘label’ is interpreted as requiring two separate wire tags, one containing the source information and the other containing the destination information, which is incorrect.

16.1.2 Where wires terminate on instrument or device terminals, the instrument tag number and terminal designation (+) or (-), shall be used in lieu of terminal strip identification.

16.1.3 Wire tag information shall be permanently marked in block alpha numeric or typed on tubular, heat-shrinkable, slip-on sleeves. Wrap-around, snap-on or self-adhesive wire markers shall not be used. Handwritten wire tags are not acceptable. Exceptions:

Alternate wire tagging schemes, which conform to established local practice, may be used for extensions to existing facilities.
Plastic sleeves that are specifically designed to fit on a specific wire gauge and come with pre-printed alpha/numeric inserts may be used for wire tags.

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16.1.4

16.1.5

A clear heat shrink sleeve shall be installed over the wire tag for all instruments that use rust preventive grease on its threaded wiring access cover. Spare pairs/triads in multi-pair/triad cables shall be labeled “Spare” in addition to the destination and source terminal numbers. The “Spare” designation shall be on a separate wire tag installed on the twisted pair and not part of the source/destination tag.

Note: It is not allowed for the “Spare” designation to be printed on each source/destination wire tag because this would require new tags to be made when the conductors are utilized. This is inefficient since the source/destination designations do not change.

Cable Tagging

16.2.1

All cables shall be tagged, at each end, with a cable-tag. 16.2.1.1 Homerun cables shall be tagged with the assigned “IC” cable

number.

16.2.1.2 The cable tagging philosophy for cables routed from junction

boxes to field instruments shall be defined by the Proponent Representative.

Note: Some Proponent facilities prefer to tag the instrument cables with the instrument cable number (e.g., IC-1249) where other facilities prefer to tag the cables with the instrument tag number (e.g., TT-1249).

16.2.2

Cable-tags for outdoor applications shall be 316 SS with permanently marked alphanumeric characters, i.e., raised or stamped characters. The cable-tag shall be securely attached to the cable with cable tie in accordance to paragraph 5.7.1. Where cable tags are required for indoor applications high quality plastic cable tags secured using cable ties per paragraph 5.7.3 shall be used.

Terminal Reference

16.3.1

16.3.2

Each row of terminals shall be uniquely identified alphanumerically, e.g., TS-101, TS-102, etc. The terminals in each row shall be sequentially numbered starting at number one (1).

Grounding

General

17.1.1

Electrical systems must be connected to ground for the protection of personnel and equipment from fault currents (AC safety ground) and to minimize electrical interference in signal transmission circuits (Instrument DC & Shield Ground).

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17.1.2

17.1.3

17.1.4

17.1.5

17.1.6

Two grounding systems are required for instrumentation systems: a) Safety Ground for personnel safety b) Instrumentation DC & Shield Ground Both safety ground and instrumentation DC & Shield ground must conform to NEC, Article 250. Grounding system recommendations and requirements provided by manufacturers of instrumentation and control systems (e.g., distributed control systems and ESD Systems) shall also be taken into consideration. For all grass root projects, process automation grounding scheme shall be per Library Drawing DC-950150-001. For all grass root projects, safety grounding wires shall be green with yellow tracers. Instrumentation DC & Shield grounding wires shall be green.

Safety Ground

17.2.1

17.2.2

All exposed non-current-carrying metallic parts that could become energized with hazardous potentials must be reliably connected to the equipment grounding circuits. This assures that hazardous potential differences do not exist between individual instrument cases or between an instrument case and ground. Therefore, all metal equipment and enclosures within a panel or series of panels (i.e., instrument cases, hinged doors, racks, etc.) shall be bonded with bonding jumpers and connected to a safety ground bus with a minimum copper wire size of 14 AWG. Two copper conductors, 25 mm² minimum, shall be connected from the safety ground bus to a single tie point on the safety ground grid in a closed loop configuration. Safety ground connections must be made such that when a case-grounded instrument is removed, the integrity of the rest of the safety ground system is maintained. Enclosures for field instruments shall be grounded as follows: 17.2.2.1

Instruments Operating at Greater than 50 Volts The enclosures for instrument devices operating at 120 VAC, 230 VAC, or 125 VDC shall be grounded per SAES- P-111. Instruments Operating at Less than 50 VDC The enclosures for instrument devices operating at 50 VDC or less may be grounded using one of the following options: a) Connecting the enclosure directly to the grid using

25 mm² ground wire.

b) Connecting the enclosure to a grounded instrument stand or other supporting structure, provided that the instrument device is properly fastened and the mounting clamp is mechanically and electrically in intimate contact with the stand.

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c) Using the conduit as a ground conductor, provided that the conduit system is continuous and properly grounded. A bonding jumper shall be used across any flexible conduit at the instrument end. All conduit fittings shall be listed as suitable for grounding.

d) Using the cable armor (assuming armored cable is used)

provided that the following criteria are met:

The armor construction is suitable as a grounding path per

the NEC.

The cable glands, on each end of the armored cable, shall be designed to bond the armor to the gland (i.e., listed as suitable for grounding).
The armored cable runs in one continuous length from a properly grounded junction box to the device being grounded, i.e., no splices are permitted.
The armored cable is not in direct contact with the soil for

any portion of the run.

Instrument DC and Shield Ground

17.3.1

17.3.2

The purpose of instrument DC & Shield ground bus bar is to reduce the effect of electrical interference upon the signal being transmitted. A DC & Shield ground bus bar shall be provided within each cabinet for consolidating instrument signal commons and cable shield drain wires. This ground bus shall be isolated from the safety ground system and from the body of the cabinet except at the plant reference point as shown in Library Drawing DC-950150-001. Each instrument signal common shall be connected to the isolated instrument DC and Shield ground bus with copper wire sized to carry the expected fault current or 12 AWG, whichever is larger using a screw-type compression ring lug. Two insulated copper conductors, 25 mm² minimum, shall be connected from the instrument DC and Shield ground bus within each cabinet in any building to a single tie point on the Master Instrument Ground bar (MIG) within the building in a closed loop configuration. The resistance from the isolated instrument DC and Shield ground bus to the plant ground grid shall be less than 1 ohm. Exception: For offshore platforms, AC and DC & Shield ground bus bars within standalone cabinets can be directly connected to dedicated and separate points on the platform overall grounding grid. The sizes of the grounding wires shall be per Library Drawing DC-950150-001.

Grounding within Control and Process Interface Buildings

17.4.1

In cases where there are many ground buses such as in control or process interface buildings, isolated instrument DC and Shield ground bars from all cabinets shall be consolidated into a Master Instrument Ground Bus (MIG)

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17.4.2

17.4.3

17.4.4

17.4.5

located within that building. Similarly, AC ground bus bars shall be consolidated into a Master Safety Ground Bus (MSG). The Master instrument ground bar shall be connected to the PAS Master Reference Ground (MRG). The MRG should then be connected in a loop configuration to a single point on the plant grounding grid as shown in Library Drawing DC-950150-001. Instrument cable shields shall be connected to the instrument DC and Shield ground bus in accordance with paragraph 14.3.2. Bonding cabinet AC or DC and Shield ground bus bars in a daisy-chain connection is not acceptable. The connections of the ground wires to the ends of the cabinet bus bars and to the building master ground bars (MIG & MSG) shall be via suitable screw-type compression ring lugs.

Special Considerations

Some equipment (data highways, computers, distributed control systems, etc.) may require special provisions for grounding. Manufacturers’ recommendations should be carefully evaluated at all times.

Ground Fault Detection

17.6.1 When critical control systems, i.e., emergency shutdown (ESD) systems,

17.6.2

utilize fully floating DC power where both positive and negative buses are isolated from earth ground, a selective ground fault detection system shall be incorporated to detect leakage current from field I/O wiring to ground. Due care must be taken to ensure that circuits from one ground fault selector switch will not be cross-connected to circuits from any other ground fault selector switch (e.g., at common annunciator points, lamp test connections).

Lightning Protection

Lightning protection shall be provided where required in SAES-P-111.

Intrinsically Safe Systems

General

The use of Intrinsic Safety as a protection method is required for all instruments located within Class I, Zone 0 areas. In other electrical hazardous areas (Class I, Zone 1 and Zone 2), IS systems shall only be used where other methods of protection are impractical.

Equipment

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Electrical Systems for Instrumentation

18.2.1

18.2.2

Only equipment, apparatus or devices that have been listed as intrinsically safe (I.S.) by a third party testing laboratory shall be used or installed under this standard. Exception: If the field device is classified as simple apparatus, certification is not required. As third party testing laboratories, only the agencies referred in SAES-P-100 are acceptable under this standard. For equipment, devices, or apparatus certified as intrinsically safe, only those that are certified as category Ex “ia” shall be used.

Notes: The identifying letter for intrinsic safety is “i” followed by either “a,” or “b,” or “c” identifying whether the equipment is suitable for Zone 0 (ia) or Zone 1 (ib) or Zone 2 (ic). Intrinsically safe systems are limited by this standard to those certified “ia” to simplify the selection process and to ensure that an I.S. system is safe to install in all locations (Zones 0, 1, or 2).

The ‘ic’ concept has replaced the ‘energy-limited’ (nL) of the type ‘n’ Standard IEC 60079-15 and ‘non-incendive’ concept of North American standards. “ic” is applicable for Foundation Fieldbus only. When Intrinsically Safe systems are used, ‘ia” level of protection shall be specified to ensure a safe installation across all locations.

Procedure

The proponent/PMT shall adhere to the following procedure when using the intrinsic safety protection technique. 18.3.1

The proponent/PMT shall prepare an I.S. System design package during engineering design. During installation and commissioning, the I.S. system shall be inspected by the proponent and the Inspection Department for compliance with the I.S. control drawing.

18.3.2

Note: P&CSD/PASD/IU can be contacted for any issues during engineering design, installation and commissioning. Exception: Intrinsically safe circuits that are part of third party certified systems, are factory installed, and require no modification in the field, are acceptable without an I.S. design package review and inspection required in paragraphs 18.3.2 above.

I.S. System Design Package

The I.S. system design package shall consist of the following documentation: 18.4.1 18.4.2

Electrical area classification drawing in accordance with SAES-B-068. Plan drawing showing the overall I.S. system from the instruments in the hazardous areas to the Process Control System in the non-hazardous area (usually in the Process Interface Building or the control room). For sake of clarity, the drawing shall show the I.S. system only.

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Electrical Systems for Instrumentation

18.4.3

18.4.4

18.4.5

18.4.6

Demarcation lines between the non-hazardous (safe) area and the hazardous area portions of system shall be clearly shown. The respective areas shall be labeled “non-hazardous (safe)” and “hazardous area”. Loop diagrams showing termination assignments in junction boxes and marshalling panels. I.S. System Certification Information A system control drawing shall be provided including all entity concept parameters for each component in the intrinsically safe system. I.S. system control drawings shall be prepared in accordance with ISA RP12.2.02. The I.S. system control drawing shall reference the applicable Instrument Loop Diagram (ILD) ref. SAES-J-003. The certifying agency, certificate number, and date of certification shall be supplied for each component in the intrinsically safe system. Exception: If the field device is classified as simple apparatus, certification of the device itself is not required. However, all devices included in the Intrinsically Safe loop, shall be shown on the System Control Drawing. To assess the intrinsic safety of the interconnected equipment, the entity parameters shall be compared (including the calculated interconnecting cable capacitance and inductance) in accordance with ISA TR12.2.

Note: The I.S. system “control drawing” consolidates the entity parameters for the intrinsically safe field instrument and the associated apparatus as well as the allowable capacitance and inductance of the interconnecting cables. Having this information on a single drawing referenced to the Instrument Loop Drawing (ILD) is critical when making modifications to the loop in the future. Cable/Wire Information 18.4.5.1 Size of individual pair or triad, capacitance per unit length, and

inductance per unit length. 18.4.5.2 Cable length, meters (feet) Insulation Rating 18.4.5.3 Interconnecting cables shall be specified with a minimum insulation rating of 600 volts.

18.4.5.4 Cable manufacturer Grounding Plan 18.4.6.1 Overall control building grounding plan 18.4.6.2

I.S. system grounding plan for associated apparatus, cable shields, and enclosures.

Installation

As proper installation is critical for intrinsically safe circuits to operate safely, special attention shall be given to the installation requirements below: 18.5.1

Field Instrument

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Electrical Systems for Instrumentation

18.5.2

The intrinsically safe instrument enclosure shall be sealed to provide adequate ingress protection (NEMA 4X or IP 66).

Note: With Intrinsically Safe systems, the instrument enclosure and wire raceway (conduit, tray, etc.) only provide mechanical protection. Therefore, an instrument installed as Intrinsically Safe does not require an “explosion proof” seal and the interconnecting cable raceway must only be sealed at the point of exit from the hazardous area if it can transport hazardous gases into the non-hazardous area. Interconnecting Wiring Typical instrument wiring consists of a shielded, twisted pair/triad from a field located device to an I.S. Junction Box and onward via an I.S. homerun cable to the associated apparatus (typically the IS barrier) located in a marshalling cabinet in a control room or process interface building. The interconnecting cables used in an intrinsically safe circuit must be electrically compatible with the intrinsically safe components being used. Cable capacitance and inductance contributions must be included on the system certificate or system control drawing. 18.5.2.1 Conductors of intrinsically safe circuits shall not be placed in any

raceway, cable tray, or cable with conductors of any non- intrinsically safe circuit.

18.5.2.2 Mechanical protection of the conductors to each individual

instrument from the field-mounted instrument to the field junction box shall be provided in the form of conduit or steel wire armor and cable tray per section 13. Where cable systems are used with the cable tray, the cable shall be well supported throughout its length and the length of unsupported cable at the field instrument should not exceed 0.5 meters.

18.5.2.3 Dedicated intrinsically safe field termination cabinets (junction

boxes) shall be provided to maintain positive separation of intrinsically safe from non-intrinsically safe wiring. Where several intrinsically safe instrumentation loops are involved, individual pair/triad from each instrument located in the field may be routed to a common field termination cabinet. The field termination cabinet will serve as a transition point from individual pair/triad to a multi-pair/triad cable. Multi-core cables shall not combine intrinsically safe and non-intrinsically safe signals. Enclosures (Junction Boxes) for IS instruments in outdoor areas shall be a minimum of NEMA Type 4X in accordance with NEMA ICS 6 and NEMA 250 or a minimum of IEC 60529 Type IP 66.

18.5.2.4 Multi-pair/triad cables shall be routed from the field termination cabinets (junction boxes) to the control room or process interface building in cable trays, in conduits, or by direct burial cable

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18.5.3

provided the cable is approved for cable tray use or for direct burial. Cables shall be sealed against the passage of gas and vapors as required by latest edition of the National Electrical Code NFPA 70 and SAES-B-008.

18.5.2.5 The standard practice of separating thermocouple, 4-20 milliamp,

and digital alarm signals shall be observed. This segregation shall be maintained in the field via dedicated, intrinsically safe field junction boxes. Signal segregation shall be maintained up to the marshalling panels, where signals may be consolidated to the extent specified in this standard. Care shall be taken to avoid locating interconnecting cables containing intrinsically safe circuits close to overhead power distribution lines or heavy current carrying cables. Refer to Section 14 for minimum spacing requirements between parallel cable runs of different signal types. Note: The associated apparatus (I.S. barrier) in an Intrinsically Safe loop only protects the field device and interconnecting wiring from unsafe voltage levels on the controls system side of the “non- hazardous” terminals. Positive separation between Intrinsically Safe interconnecting cables and non-Intrinsically Safe conductors ensures that the Intrinsically Safety of the loop is not compromised by a fault on the field side of the associated apparatus “hazardous area” terminals.

Termination 18.5.3.1

I.S. system wiring shall be terminated in dedicated marshalling cabinets or compartments within marshalling cabinets that house the associated apparatus. I.S. cables shall enter the cabinet through cable entries completely separate and opposite from the non-intrinsically safe connecting cables to the control system. Cabinets that contain the associated apparatus shall be located within air-conditioned analyzer shelters, process interface buildings, or control rooms. Exception: The associated apparatus may be installed in the field when supplied as part of the vendors standard product offering certified for use in the intended hazardous area. Note: The associated apparatus (barrier) may be installed within a field mounted, NEMA 4X enclosure provided the certification mark on the device identifies it may be safely installed in the intended hazardous location. The certification marking on the associated apparatus is completely separate from the entity parameters listed for the output terminals (used to match the associated apparatus with the intrinsically safe instrument located in the hazardous area).

18.5.3.2 The I.S. cables from the field instrument shall be terminated on

the “hazardous area” terminations of the associated apparatus and shall be secured or tie-wrapped separately from the non-

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intrinsically safe cables terminated on the opposite end “safe area” terminals of the associated apparatus. A minimum of 2 inches (50 mm) shall be maintained between the I.S. and non-I.S. cables within the cabinet that contains the associated apparatus.

18.5.3.3 All spare wires shall be terminated at terminal blocks and

grounded to the intrinsic safety ground bus. Unused wires shall also be insulated at their hazardous area ends.

18.5.3.4 The minimum clearances between terminals of intrinsically safe circuits and any grounded metal shall be 3 mm (⅛ inch), unless that terminal is intended to be grounded. The clearance between two terminals of different intrinsically safe circuits shall be at least 6 mm (¼ inch).

18.5.4 Grounding I.S. systems 18.5.4.1

18.5.4.2

I.S. system grounding shall conform to the I.S. system vendor’s grounding recommendations and all I.S. control drawing requirements. If no specific vendor grounding scheme exists, NFPA 70 Article 504 and Library Drawing DC-950150 can be followed. All intrinsically safe circuit grounds shall be connected to the grounding system with dedicated I.S. grounding conductors separate from non-intrinsically safe, or equipment, or power grounds. Note: In the case of Radar Tank Gauging (RTG) systems, the tank grounding system (or tank structure) serves as both the intrinsically safe ground and the electrical safety ground. The installation of a separate IS ground rod at each tank is not required. In cabinets housing the associated apparatus, the intrinsic safety ground bus shall be connected to a node in the overall plant ground grid by dedicated, redundant, insulated copper cables not smaller than #4 AWG. To identify the intrinsically safe grounding conductors as being different from other ground connections, the grounding conductor insulation color shall be green with blue tracer (or banded with blue tape). Where screens/shields are used, they shall be covered by an outer insulating sheath. They shall be grounded at the associated apparatus intrinsic safety ground point and insulated at the hazardous area end. Where screened multipair/multitriad cables interconnect within field junction boxes with individual screened pair/triad cables, insulated terminals shall be provided for the ongoing continuity of the screens/shields.

18.5.4.3 When Zener diode type barriers are used, the maximum

resistance between the farthest point on the intrinsic safety barrier ground and the plant grounding system (the point at which the

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Electrical Systems for Instrumentation

18.5.5

incoming electricity supply neutral is grounded) shall not exceed 1 Ohm.

Note: The low impedance (1 ohm or less) ground connection is not required when active galvanic isolators are used as the associated apparatus.

18.5.4.4 All metal enclosures for intrinsically safe circuits shall be

grounded to the plant grounding system with a minimum of #4 AWG copper wire with green insulation.

18.5.4.5 All metal cable trays used for intrinsically safe wiring shall be grounded to the plant grounding system with a minimum of #4 AWG copper wire with green insulation.

18.5.4.6 Cable protective armor, if used, shall be grounded using proper grounding means to plant grounding system at the field junction box.

Identification 18.5.5.1 All intrinsically safe system components shall be also identified. 18.5.5.2 All junction boxes, cable trays, conduits, cables, cabinets, and instrument housings shall be labeled as containing intrinsically safe circuits or equipment. The means of identification shall be visible and long-lasting after installation. Label spacing on cable tray, conduit, and interconnecting cables shall not exceed 25 feet (8 meters).

Note: Self-sticking markers are recommended (e.g., Brady Polyester 0.112 mm thickness, permanent acrylic adhesive 0.026 mm, clear over laminate type). Specify light blue letters on white background for the control cabinets, conduit runs, and local junction boxes (¾ inch x 8 inches length color field with ½ inch letter height).

18.5.5.3 Light blue color coding shall be used to identify intrinsically safe

wiring. The preferred practice is to specify intrinsically safe interconnecting cables with a blue outer jacket. Alternatively, blue sleeves slipped over the jacket at all points of termination may be used to identify I.S. wiring.

Modification of Intrinsically Safe Systems

18.6.1

18.6.2

A log shall be maintained, by the responsible proponent organization, of all modifications to existing I.S. systems. Drawings shall be modified and the design approved using Entity Concept parameters (Reference ISA RP12.6.01 and ISA TR12.2). Only devices, apparatus, and equipment that have been listed as Intrinsically Safe in accordance with section 18.2.1 shall be used when existing Intrinsically Safe instrumentation loops or systems are modified.

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Electrical Systems for Instrumentation

18.6.3

Exception: If the field device is classified as a simple apparatus, certification is not required. Installation shall be in accordance with existing system documentation (System Control Drawing) and manufacturers’ instructions.

Maintenance and Testing

18.7.1

18.7.2

18.7.3

18.7.4

An I.S. system may be tested and maintained under live (working) conditions provided the portable test equipment used has been certified and approved as intrinsically safe for the particular atmospheric hazard. Otherwise, a hot work permit shall be issued. Only safety barriers/isolators of the same type, make, or catalog number shall be used to replace defective safety barriers/isolators. Only devices of the same make, type, and catalog number or replacement recommended by the manufacturer shall be used to replace any device in the system. Any changes, additions/deletions of components to/from a loop, shall be recorded at the operating facility in the appropriate Saudi Aramco drawings.

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Document History

26 March 2020

1 January 2018 19 January 2017

10 August 2016 17 May 2015 20 July 2014

Major revision by merging SAES-J-903 requirements into SAES-J-902, and canceling SAES-J-903 Editorial revision to modify paragraph 12.3.2 (Exception). Major revision to allow the use of non-metallic for junction boxes in corrosive environment, mixing of various signals of the same level, allowed the use of pressure-loaded terminal blocks, and relaxed the requirement for voltage drop for DC circuits in line with industry practices among other changes. Major revision to align with industry standards Editorial revision to change primary contact information. Revised the Next Planned Update, reaffirmed the content of the document, and reissued as major revision primarily intended to edit some of the words and provide clarifications to some of the existing requirements.

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