Recommended Practice for Wiring Methods for Hazardous (Classified) Locations Instrumentation Part 1: Intrinsic Safety

Transcription

1 RECOMMENDED PRACTICE ANSI/ISA-RP Formerly ANSI/ISA-RP (R2002) Recommended Practice for Wiring Methods for Hazardous (Classified) Locations Instrumentation Part 1: Intrinsic Safety Approved 16 April 2003

2 ANSI/ISA-RP Recommended Practice for Wiring Methods for Hazardous (Classified) Locations Instrumentation Part 1: Intrinsic Safety ISBN: Copyright 2003 by ISA The Instrumentation, Systems, and Automation Society. All rights reserved. Not for resale. Printed in the United States of America. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means (electronic mechanical, photocopying, recording, or otherwise), without the prior written permission of the Publisher. ISA 67 Alexander Drive P.O. Box Research Triangle Park, North Carolina 27709

3 3 ANSI/ISA-RP Preface This preface, as well as all footnotes and annexes, is included for information purposes and is not part of ANSI/ISA-RP This document has been prepared as part of the service of ISA the Instrumentation, Systems, and Automation Society toward a goal of uniformity in the field of instrumentation. To be of real value, this document should not be static but should be subject to periodic review. Toward this end, the Society welcomes all comments and criticisms and asks that they be addressed to the Secretary, Standards and Practices Board; ISA; 67 Alexander Drive; P. O. Box 12277; Research Triangle Park, NC 27709; Telephone (919) ; Fax (919) ; standards@isa.org. The ISA Standards and Practices Department is aware of the growing need for attention to the metric system of units in general, and the International System of Units (SI) in particular, in the preparation of instrumentation standards. The Department is further aware of the benefits to USA users of ISA standards of incorporating suitable references to the SI (and the metric system) in their business and professional dealings with other countries. Toward this end, this Department will endeavor to introduce SI-acceptable metric units in all new and revised standards, recommended practices, and technical reports to the greatest extent possible. Standard for Use of the International System of Units (SI): The Modern Metric System, published by the American Society for Testing & Materials as IEEE/ASTM SI 10-97, and future revisions, will be the reference guide for definitions, symbols, abbreviations, and conversion factors. It is the policy of ISA to encourage and welcome the participation of all concerned individuals and interests in the development of ISA standards, recommended practices, and technical reports. Participation in the ISA standards-making process by an individual in no way constitutes endorsement by the employer of that individual, of ISA, or of any of the standards, recommended practices, and technical reports that ISA develops. CAUTION ISA ADHERES TO THE POLICY OF THE AMERICAN NATIONAL STANDARDS INSTITUTE WITH REGARD TO PATENTS. IF ISA IS INFORMED OF AN EXISTING PATENT THAT IS REQUIRED FOR USE OF THE DOCUMENT, IT WILL REQUIRE THE OWNER OF THE PATENT TO EITHER GRANT A ROYALTY-FREE LICENSE FOR USE OF THE PATENT BY USERS COMPLYING WITH THE DOCUMENT OR A LICENSE ON REASONABLE TERMS AND CONDITIONS THAT ARE FREE FROM UNFAIR DISCRIMINATION. EVEN IF ISA IS UNAWARE OF ANY PATENT COVERING THIS DOCUMENT, THE USER IS CAUTIONED THAT IMPLEMENTATION OF THE DOCUMENT MAY REQUIRE USE OF TECHNIQUES, PROCESSES, OR MATERIALS COVERED BY PATENT RIGHTS. ISA TAKES NO POSITION ON THE EXISTENCE OR VALIDITY OF ANY PATENT RIGHTS THAT MAY BE INVOLVED IN IMPLEMENTING THE DOCUMENT. ISA IS NOT RESPONSIBLE FOR IDENTIFYING ALL PATENTS THAT MAY REQUIRE A LICENSE BEFORE IMPLEMENTATION OF THE DOCUMENT OR FOR INVESTIGATING THE VALIDITY OR SCOPE OF ANY PATENTS BROUGHT TO ITS ATTENTION. THE USER SHOULD CAREFULLY INVESTIGATE RELEVANT PATENTS BEFORE USING THE DOCUMENT FOR THE USER S INTENDED APPLICATION. HOWEVER, ISA ASKS THAT ANYONE REVIEWING THIS DOCUMENT WHO IS AWARE OF ANY PATENTS THAT MAY IMPACT IMPLEMENTATION OF THE DOCUMENT NOTIFY THE ISA STANDARDS AND PRACTICES DEPARTMENT OF THE PATENT AND ITS OWNER. ADDITIONALLY, THE USE OF THIS DOCUMENT MAY INVOLVE HAZARDOUS MATERIALS, OPERATIONS OR EQUIPMENT. THE DOCUMENT CANNOT ANTICIPATE ALL POSSIBLE APPLICATIONS OR ADDRESS ALL POSSIBLE SAFETY ISSUES ASSOCIATED WITH USE IN HAZARDOUS CONDITIONS. THE USER OF THIS DOCUMENT MUST EXERCISE SOUND PROFESSIONAL JUDGMENT CONCERNING ITS USE AND APPLICABILITY UNDER THE USER S

4 ANSI/ISA-RP PARTICULAR CIRCUMSTANCES. THE USER MUST ALSO CONSIDER THE APPLICABILITY OF ANY GOVERNMENTAL REGULATORY LIMITATIONS AND ESTABLISHED SAFETY AND HEALTH PRACTICES BEFORE IMPLEMENTING THIS DOCUMENT. THE USER OF THIS DOCUMENT SHOULD BE AWARE THAT THIS DOCUMENT MAY BE IMPACTED BY ELECTRONIC SECURITY ISSUES. THE COMMITTEE HAS NOT YET ADDRESSED THE POTENTIAL ISSUES IN THIS VERSION. The following people served as voting members of ISA Subcommittee SP12.6: NAME COMPANY D. Bishop, Managing Director Consultant R. Masek, Chair CSA International N. Abbatiello Eastman Kodak Co. R. Allen Honeywell Inc. W. Bennett Pepperl + Fuchs Inc. K. Boegli Phoenix Contact Inc. C. Bombria Consultant J. Bossert Hazloc Inc. R. Cardinal Bently Nevada LLC A. Engler EGS Electrical Group T. Feindel R. Stahl Inc. W. Fiske Intertek Testing Services L Goettsche Consultant B. Larson Turck Inc. J. Miller Detector Electronics Corp. A. Mobley 3M Co. O. Murphy Brooks Instruments E. Olson Ellis Engineering Co. J. Oudar ExLoc Corp. A. Page MSHA Approval & Certification Center B. Schaefer Underwriters Laboratories Inc. P. Schimmoeller CSA International T. Schnaare Rosemount Inc. D. Wechsler Dow Chemical Co. C. Wellman DuPont Engineering The following people served as voting members of ISA Committee SP12: NAME COMPANY T. Schnaare, Chair Rosemount Inc. W. Lawrence, Vice Chair FM Approvals D. Bishop, Managing Director Consultant N. Abbatiello Eastman Kodak Company D. Ankele Underwriters Laboratories Inc. B. Apel MSA Instrument A. Ballard Crouse Hinds Division of Cooper Industries W. Bennett Pepperl + Fuchs Inc. K. Boegli Phoenix Contact Inc. R. Brodin Fisher Controls Intl. Inc. R. Buschart PC & E Inc. R. Cardinal Bently Nevada Corp. C. Casso Schlumberger Oilfield Services M. Coppler Ametek Inc. J. Cospolich Waldemar S. Nelson & Company Inc.

5 5 ANSI/ISA-RP J. Costello Henkel Corporation S. Czaniecki Intrinsic Safety Concepts Inc. T. Dubaniewicz NIOSH U. Dugar Mobil Chemical Company A Engler EGS Electrical Group T. Feindel R. Stahl Inc. W. Fiske Intertek Testing Services G. Garcha GE Power Systems D. Jagger 9 Darnton Gardens F. Kent Honeywell Inc. J. Kuczka Killark B. Larson Turck Inc. E. Magison Consultant R. Masek CSA International A. Mobley 3M Company A. Page MSHA Approval & Certification Center J. Propst Equilon Enterprises P. Schimmoeller CSA International D. Wechsler Dow Chemical Company C. Wellman DuPont Engineering This document was approved for publication by the ISA Standards and Practices Board on 22 October NAME COMPANY M. Zielinski, Chair Emerson Process Management D. Bishop David N Bishop, Consultant D. Bouchard Paprican M. Cohen Consultant M. Coppler Ametek, Inc. B. Dumortier Schneider Electric W. Holland Southern Company E. Icayan ACES Inc A. Iverson Ivy Optiks R. Jones Dow Chemical Company V. Maggioli Feltronics Corporation T. McAvinew ForeRunner Corporation A. McCauley, Jr. Chagrin Valley Controls, Inc. G. McFarland Westinghouse Process Control Inc. R. Reimer Rockwell Automation J. Rennie Factory Mutual Research Corporation H. Sasajima Yamatake Corporation I. Verhappen Syncrude Canada Ltd. R. Webb POWER Engineers W. Weidman Parsons Energy & Chemicals Group J. Weiss KEMA Consulting M. Widmeyer Stanford Linear Accelerator Center C. Williams Eastman Kodak Company G. Wood Graeme Wood Consulting

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7 7 ANSI/ISA-RP Table of Contents Preface Purpose Scope Definitions Article 504 and 505 of the NEC (ANSI/NFPA ) with explanation Guidelines for combinations of apparatus under the entity concept Maintenance and inspection Annex A Explanatory notes Annex B Wiring in hazardous (classified) locations Annex C Marking for the zone classification system Annex D References... 57

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9 9 ANSI/ISA-RP Purpose 1.1 This recommended practice is intended to promote the uniform installation of intrinsically safe systems for hazardous (classified) locations. Information is provided to clarify and explain the requirements of Articles 504 and 505 of the National Electrical Code (NEC ) ANSI/NFPA 70. (For further information, see Annex A.) NOTE Throughout clause 3 and 4, text that has been excerpted from the National Electrical Code (NEC ) is distinguished from the main body of text as follows: NEC Article 500, 504 and 505 text is shaded and indented at the left and right margins. Other excerpted NEC text (such as articles on sealing) is shaded but not indented. Text from the National Electrical Code (NEC ) is reprinted with permission from NFPA , the National Electrical Code, Copyright 2001, National Fire Protection Association, Quincy, MA National Electrical Code and NEC are registered trademarks of the National Fire Protection Association, Inc., Quincy, MA This recommended practice applies to the installation of intrinsically safe systems for use in hazardous (classified) locations. 2 Scope 2.1 This recommended practice provides guidance to those who design, install, and maintain intrinsically safe systems for hazardous (classified) locations. 2.2 This recommended practice should be used in conjunction with nationally recognized codes that cover wiring practices such as the National Electrical Code (NEC ), ANSI/NFPA 70, and the Canadian Electrical Code (CEC) Part I, CSA C This recommended practice is not intended to: a) include guidance for designing, testing, or repairing intrinsically safe or associated apparatus; or b) apply to the use of portable equipment, except as shown on the control drawing. 3 Definitions For purposes of this recommended practice, the following definitions apply: 3.1 approved: acceptable to the authority having jurisdiction (for additional information, see NEC Article 100). 3.2 associated apparatus: Associated Apparatus: Apparatus in which the circuits are not necessarily intrinsically safe themselves, but that affect the energy in the intrinsically safe circuits and are relied on to maintain intrinsic safety. Associated apparatus may be either of the following:

10 ANSI/ISA-RP Electrical apparatus that has an alternative-type protection for use in the appropriate hazardous (classified) location, or 2. Electrical apparatus not so protected that shall not be used within a hazardous (classified) location. FPN No. 1: Associated apparatus has identified intrinsically safe connections for intrinsically safe apparatus and also may have connections for nonintrinsically safe apparatus. FPN No. 2: An example of associated apparatus is an intrinsic safety barrier, which is a network designed to limit the energy (voltage and current) available to the protected circuit in the hazardous (classified) location, under specified fault conditions. 3.3 authority having jurisdiction (AHJ): the organization, office, or individual responsible for approving equipment, materials, an installation, or a procedure. 3.4 channel: an ungrounded conductor in a grounded intrinsically safe circuit, or a conductor and its reference in a galvanically isolated intrinsically safe circuit. 3.5 control drawing: Control Drawing: A drawing or other document provided by the manufacturer of the intrinsically safe or associated apparatus, or of the nonincendive field wiring apparatus or associated nonincendive field wiring apparatus, that details the allowed interconnections between the intrinsically safe and associated apparatus or between the nonincendive field wiring apparatus or associated nonincendive field wiring apparatus. 3.6 corrective maintenance: any maintenance activity that is not normal in the operation of equipment and requires access to the equipment's interior. Such activities are expected to be performed by qualified personnel who are aware of the hazards involved. Such activities typically include locating causes of faulty performance, replacement of defective components (see 6.2.1), adjustment of internal controls, and the like. Corrective maintenance is referred to simply as maintenance in clause different intrinsically safe circuits: Different Intrinsically Safe Circuits: Intrinsically safe circuits in which the possible interconnections have not been evaluated and identified as intrinsically safe. 3.8 entity evaluation: a method used to determine acceptable combinations of intrinsically safe apparatus and connected associated apparatus that have not been investigated in such combination.

11 11 ANSI/ISA-RP Entity parameters for intrinsically safe apparatus: C i : I i or I max : L i : L i /R i : P i : U i or V max : Total equivalent internal capacitance of the apparatus that is considered as appearing across the connection facilities of the apparatus. Maximum current (peak a.c. or d.c.) that can be applied to the connection facilities of the intrinsically safe apparatus circuits without invalidating intrinsic safety. The maximum input current may be different for different terminals. Total equivalent internal inductance of the apparatus that is considered as appearing across the connection facilities of the apparatus. The maximum value of ratio of inductance to resistance that is considered as appearing across the terminals of the intrinsically safe apparatus. Maximum power in an external intrinsically safe circuit that can be applied to the connection facilities of the apparatus. The maximum input power may be different for different terminals. Maximum voltage (peak a.c. or d.c.) that can be applied to the connection facilities of the apparatus without invalidating the type of protection. The maximum input voltage may be different for different terminals Entity parameters for associated apparatus: C o or C a : I o. or I sc : L o or L a : Maximum capacitance in an intrinsically safe circuit that can be connected to the connection facilities of the apparatus. Maximum current (peak a.c. or d.c.) in an intrinsically safe circuit that can be taken from the connection facilities of the apparatus. Maximum inductance in an intrinsically safe circuit that can be connected to the connection facilities of the apparatus. L o /R o or L a /R a: The maximum value of ratio of inductance to resistance that may be connected to the intrinsically safe circuit of the associated apparatus. P o : U o or V oc : Maximum electrical power in an intrinsically safe circuit that can be taken from the apparatus. Maximum output voltage (peak a.c. or d.c.) in an intrinsically safe circuit that can appear under open-circuit conditions at the connection facilities of the apparatus Additional entity parameters for associated apparatus with multiple channels may include the following: I t : V t : The maximum DC or peak AC current that can be drawn from any combination of terminals of a multiple-channel associated apparatus configuration. The maximum DC or peak AC open circuit voltage that can appear across any combination of terminals of a multiple-channel associated apparatus configuration. 3.9 galvanic isolation: the transfer of electrical power or signal from one circuit to another by means that do not include a direct electrical connection (e.g., through an isolating transformer or optical coupler).

12 ANSI/ISA-RP hazardous (classified) location: a location in which fire or explosion hazards may exist due to flammable gases or vapors, flammable liquids, combustible dust, or ignitable fibers or flyings identified: Identified (as applied to equipment). Recognizable as suitable for the specific purpose, function, use, environment, application, and so forth, where described in a particular Code requirement. FPN: Some examples of ways to determine suitability of equipment for a specific purpose, environment, or application include investigations by a qualified testing laboratory (listing and labeling), an inspection agency, or other organizations concerned with product evaluation intrinsic safety: a type of protection in which a portion of the electrical system contains only intrinsically safe equipment (apparatus, circuits, and wiring) that is incapable of causing ignition in the surrounding atmosphere. No single device or wiring is intrinsically safe by itself (except for battery-operated, self-contained apparatus such as portable pagers, transceivers, gas detectors, etc., which are specifically designed as intrinsically safe, self-contained devices), but is intrinsically safe only when employed in a properly designed intrinsically safe system. Also see "associated apparatus." 3.13 intrinsic safety barrier: a network designed to limit the energy (voltage and current) available to the protected circuit in the hazardous (classified) location, under specified fault conditions (see ISA ) intrinsic safety ground system: a grounding system that has a dedicated conductor isolated from the power system, except at one point, so that ground currents will not normally flow, and that is reliably connected to a grounding electrode in accordance with Article 250 of the NEC intrinsically safe apparatus: Intrinsically Safe Apparatus: Apparatus in which all the circuits are intrinsically safe intrinsically safe circuit: Intrinsically Safe Circuit: A circuit in which any spark or thermal effect is incapable of causing ignition of a mixture of flammable or combustible material in air under prescribed test conditions. FPN: Test conditions are described in ANSI/UL Standard for Safety, Intrinsically Safe Apparatus and Associated Apparatus for Use in Class I, II, and III, Division 1, Hazardous (Classified) Locations.

13 13 ANSI/ISA-RP intrinsically safe systems: Intrinsically Safe System: An assembly of interconnected intrinsically safe apparatus, associated apparatus, and interconnecting cables in that those parts of the system that may be used in hazardous (classified) locations are intrinsically safe circuits. FPN: An intrinsically safe system may include more than one intrinsically safe circuit labeled: equipment or materials to which has been attached a label, symbol, or other identifying mark of an organization that is acceptable to the authority having jurisdiction and concerned with product evaluation, that maintains periodic inspection of production of labeled equipment or materials, and by whose labeling the manufacturer indicates compliance with appropriate standards or performance in a specified manner (for additional information, see NEC Article 100) listed: equipment, materials or services included in a list published by an organization acceptable to the authority having jurisdiction and concerned with evaluation of products or services, that maintains periodic inspection of production of listed equipment or materials or periodic evaluation of services, and whose listing states that the equipment, material or services either meets appropriate designated standards or has been tested and found suitable for a specified purpose. (See NEC Article 100.) 3.20 qualified person: one who has skills and knowledge related to the construction and operation of the electrical equipment and installations and has received safety training on the hazards involved simple apparatus: Simple Apparatus. An electrical component or combination of components of simple construction with well-defined electrical parameters which does not generate more than 1.5 volt, 100 milliamps and 25 milliwatts, or a passive component which does not dissipate more than 1.3 watts and which is compatible with the intrinsic safety of the circuit in which it is used. FPN: The following apparatus are examples of simple apparatus: a) Passive components, for example switches, junction boxes, resistance temperature devices and simple semiconductor devices such as LEDs; b) Sources of generated energy, for example thermocouples and photocells, which do not generate more than 1.5 V, 100 ma and 25 mw.

14 ANSI/ISA-RP unclassified locations Unclassified Location: Locations determined to be neither Class I, Division 1; Class I, Division 2; Class I, Zone 0; Class I, Zone 1; Class I, Zone 2; Class II, Division 1; Class II, Division 2; Class III, Division 1; Class III, Division 2; or any combination thereof wiring drawing: a drawing or other document created by the user based upon the relevant control drawings. The wiring drawing is used by the installer to determine the type, color, and size of the wire used to connect each terminal of the equipment used in the intrinsically safe circuit. 4 Article 504 and 505 of the NEC (ANSI/NFPA ) with explanation Scope. This article covers the installation of intrinsically safe (I.S.) apparatus, wiring, and systems for Class I, II, and III locations Definitions. Associated Apparatus: Apparatus in which the circuits are not necessarily intrinsically safe themselves, but that affect the energy in the intrinsically safe circuits and are relied on to maintain intrinsic safety. Associated apparatus may be either of the following: Intrinsic safety barriers are a common form of associated apparatus. These barriers are connected between the intrinsically safe apparatus and the control equipment. Their primary purpose is to limit the energy to the hazardous location under fault conditions. They may also provide isolation, signal conditioning, or both. There are also many types of associated apparatus that normally are not referred to as intrinsic safety barriers, but have energy-limiting circuits suitable for connection directly to intrinsically safe apparatus. An example of this type of associated apparatus is a controller that is not itself intrinsically safe, but has connections for intrinsically safe sensors Application of Other Articles. Except as modified by this article, all applicable articles of this Code shall apply. Although intrinsically safe circuits are inherently low-energy circuits, they may still be shock hazards because of the operating voltage. Clause (E) provides an exception for intrinsically safe apparatus and wiring from the requirements of Articles 501 through 503 and 510 through 516. All other articles of the Code apply to intrinsically safe wiring, except as exempted by specific articles. If the rated voltage of the circuit exceeds 60 volts DC or 30 volts AC, the wiring requirements for Class 3 circuits apply. (See NEC Article 725.) Other articles may apply, depending on the functional application e.g., Article 725 for cables installed in ducts, plenums, risers, and other air-handling spaces, Article 760 for fire protective signaling systems, and Article 800 for communications circuits.

15 15 ANSI/ISA-RP Equipment Approval. All intrinsically safe apparatus and associated apparatus shall be listed. Exception: Simple apparatus, as described on the control drawing, shall not be required to be listed. Electrical equipment that is listed or labeled by a nationally recognized testing laboratory (NRTL) normally will be accepted by the AHJ. The AHJ may also accept specialized equipment not listed or labeled by a NRTL, with appropriate technical justification. A written report of the investigation and conclusion should be kept on file, and the markings on the equipment should identify the report. For additional information see NEC Equipment Installation. (A) Control Drawing. Intrinsically safe apparatus, associated apparatus, and other equipment shall be installed in accordance with the control drawing(s). Exception: A simple apparatus that does not interconnect intrinsically safe circuits. FPN: The control drawing identification is marked on the apparatus. There are three basic types of control drawings: a) Intrinsically safe apparatus and associated apparatus are both specified by manufacturer and model number. (See figure 4.1 for an example.) b) Intrinsically safe apparatus is specified by manufacturer and model number for connection to associated apparatus specified by entity parameters. (See figures 4.2a and 4.2b for an example.) c) Associated apparatus is specified by manufacturer and model number for connection to intrinsically safe apparatus that is specified by entity parameters or to simple apparatus. (See figures 4.3a and 4.3b for an example.) Control drawings that are combinations of the above types are also possible. For example, control drawings for intrinsically safe apparatus often specify permissible connections to specific associated apparatus and also specify entity parameters to allow additional flexibility in selecting associated apparatus. (See figure 4.3c for an example.) To ensure that a given interconnection forms an intrinsically safe system, it is necessary to obtain control drawings that specify each intrinsically safe apparatus and associated apparatus to be interconnected. If a control drawing of the type shown in figure 4.1 that correctly describes the interconnection is available, only that control drawing is necessary. If the intrinsic safety of the system is to be based on the comparison of entity parameters, it is necessary to obtain a control drawing for each intrinsically safe apparatus and associated apparatus. Care should be taken to ensure that the entity parameters used in the comparison apply to the specific set(s) of terminals to be interconnected.

16 ANSI/ISA-RP If the system includes only simple apparatus connected to an associated apparatus, only the associated apparatus control drawing is necessary. Multiple channels of associated apparatus should not be connected to a single simple apparatus unless specifically permitted by the control drawing. Frequently, the user creates a wiring drawing based on the control drawings provided by the manufacturers of the intrinsically safe apparatus and associated apparatus or other specification sheets that provide information such as terminal identification. NOTE Figures 4.1, 4.2a, 4.2b, 4.3a, 4.3b and 4.3.c were provided by the SP12.02 subcommittee.

17 17 ANSI/ISA-RP Hazardous (Classified) Location Class I, Division 1, Groups A, B, C and D Class II, Division 1, Groups E, F and G Class III, Division 1 or Class I, Zone 0, Group IIC Unclassified Location or Class I, Division 2, Groups A, B, C and D or Class I, Zone 2, Group IIC Safety Barrier Co. Model 2528 XYZ Series Pressure Transmitters Model No XYZ IS G Grounding Connection Maximum Cable Values GROUP A & B (or IIC) GROUP C & E (or IIB) GROUP D, F & G (or IIA) C (µf) L (mh) Lc/Rc (µh/ω) C (µf) L (mh) Lc/Rc (µh/ω) C (µf) L (mh) Lc/Rc (µh/ω) Notes: 1. The maximum unclassified location voltage, Um, is 250 V ac/dc. 2. Barrier ground shall be connected to a grounding electrode by redundant, 12 AWG or larger insulated conductors. 3. Resistance from barrier ground to Grounding electrode shall be less than 1 Ω. 4. The installation must be in accordance with the National Electrical Code, NFPA 70, Articles 504 and 505, and ANSI/ISA-RP Cable length restrictions due to cable inductance can be ignored if: L c/r c > L cable/r cable. SAFETY BARRIER Co. OLD PORT, EAST VIRGINIA CONTROL DRAWING NO. L763 MODEL 2000 SERIES SHUNT DIODE BARRIERS Approved by: John J. Smith DWG. No.: L763 Date: 6/20/00 Rev.: B Figure 4.1 Example of a control drawing for an intrinsically safe system

18 ANSI/ISA-RP Hazardous (Classified) Location Class I, Division 1, Groups A,B,C,D, T4 or T5 Class II, Division 1, Groups E,F,G Class III, Division 1 or Class I, Zone 0, Group IIC Note: T4 temperature code based on 60 C ambient T5 temperature code based on 40 C ambient 6400 SERIES TEMPERATURE TRANSMITTERS Vmax (or Ui) = 30V Imax (or Ii) = 300mA Pi = 0.65W Ci = 1.2nF Li = 3.25mH Li/Ri = 45 µh/ohm Unclassified Location ASSOCIATED APPARATUS WITH ENTITY PARAMETERS Voc (or Uo) < Vmax (or Ui) Isc (or Io) < Imax (or Ii) Po < Pi Ca (or Co) > Ci + Ccable La (or Lo) > Li + Lcable L/R verification (see note 3) 1. The installation must be in accordance with the National Electrical Code, NFPA 70, Articles 504 and 505, and ANSI/ISA-RP The 6400 Series Transmitters are Approved for Class I, Zone 0 applications as AEx ia. If connecting AEx [ib] Associated Apparatus to the 6400 Series Transmitters the I.S. circuit is only suitable for Class I, Zone 1 or Class I, Zone 2 and is not suitable for Class I, Zone 0 or Division 1 Hazardous (Classified) Locations. 3. Li may be greater than La and the cable length restrictions due to cable inductance (Lcable) can be ignored if both of the following conditions are met: La/Ra (or Lo/Ro) > Li/Ri La/Ra (or Lo/Ro) > Lcable/Rcable ABC Co., Inc. INTRINSIC SAFETY CONTROL DRAWING FOR 6400 SERIES TEMPERATURE TRANSMITTERS Division 1 and Zone 0 Application Approved by: John J. Smith DWG. No.: CD Date: 6/20/00 Rev.: B Figure 4.2a Example of a control drawing for an intrinsically safe apparatus with entity parameters for Division 1 and Zone 0

19 19 ANSI/ISA-RP Hazardous (Classified) Location Class I, Zone 1, Group IIC Note: T4 temperature code based on 60 C ambient T5 temperature code based on 40 C ambient 6400 SERIES TEMPERATURE TRANSMITTERS Vmax (or Ui) = 30V Imax (or Ii) = 300mA Pi = 0.65W Ci = 1.2nF Li = 3.25mH Li/Ri = 45 µh/ohm Unclassified Location ASSOCIATED APPARATUS WITH ENTITY PARAMETERS Voc (or Uo) < Vmax (or Ui) Isc (or Io) < Imax (or Ii) Po < Pi Ca (or Co) > Ci + Ccable La (or Lo) > Li + Lcable Lcable/Rcable verification see note 3 1. The installation must be in accordance with the National Electrical Code, NFPA 70, Articles 504 and 505, and ANSI/ISA-RP For Class I, Zone 1 applications, associated apparatus must be identified as AEx [ia] or AEx [ib]. 3. Li may be greater than La and the cable length restrictions due to cable inductance (Lcable) can be ignored if both of the following conditions are met: La/Ra (or Lo/Ro) > Li/Ri La/Ra (or Lo/Ro) > Lcable/Rcable ABC Co., Inc. INTRINSIC SAFETY CONTROL DRAWING FOR 6400 SERIES TEMPERATURE TRANSMITTERS Class I, Zone 1 Application Approved by: John J. Smith DWG. No.: CD Date: 6/20/00 Rev.: B Figure 4.2b Example of control drawing for an intrinsically safe apparatus with entity parameters for Zone 1

20 ANSI/ISA-RP Hazardous (Classified) Location Class I, Division 1, Groups A, B, C and D Class II, Division 1, Groups E, F and G Class III, Division 1 or Class I, Zone 0, Group IIC INTRINSICALLY SAFE APPARATUS WITH ENTITY PARAMETERS Unclassified Location or Class I, Division 2, Groups A, B, C and D or Class I, Zone 2, Group IIC Vmax (or Ui) > Voc (or Uo) Imax (or Ii) > Isc (or Io) Pi > Po Ci + Ccable < Ca (or Co) Li + Lcable < La (or Lo) Lcable/Rcable verification see note 5 OR SIMPLE APPARATUS 3 4 G G 1 2 Ground Conductor Connections MODEL NO. POLARITY Voc or Uo (V) Isc or Io (ma) Po (mw) GROUP A & B (or IIC) GROUP C & E (or IIB) GROUP D, F & G (or IIA) Ca La La/Ra Ca La La/Ra Ca La La/Ra or Co or Lo or Lo/Ro or Co or Lo or Lo/Ro or Co or Lo or Lo/Ro (µf) (mh) (µh/ω) (µf) (mh) (µh/ω) (µf) (mh) (µh/ω) AC The maximum unclassified location voltage, Um, is 250 V ac/dc 2 Barrier ground shall be connected to a grounding electrode per ANSI/NFPA 70, Articles The installation must be in accordance with the National Electrical Code, NFPA 70, Articles 504 and 505, and ANSI/ISA-RP Series Shunt Diode Barriers are Approved with connections to Class I, Zone 0 applications as AEx [ia]. If connecting AEx ib I.S. Apparatus to the 2000 Series Shunt Diode Barriers the I.S. circuit is only suitable for Class I, Zone 1 or Class I, Zone 2 and is not suitable for Class I, Zone 0 or Division 1 Hazardous (Classified) Locations. 5. Li may be greater than La and the cable length restrictions due to cable inductance (Lcable) can be ignored if both of the following conditions are met: La/Ra (or Lo/Ro) > Li/Ri La/Ra (or Lo/Ro) > Lcable/Rcable SAFETY BARRIER Co. OLD PORT, EAST VIRGINIA CONTROL DRAWING NO. L764 MODEL 2000 SERIES SHUNT DIODE BARRIERS Division 1 and Zone 0 Application Approved by: John J. Smith DWG. No.: L764 Date: 6/20/00 Rev.: B Figure 4.3a Example of a control drawing for an associated apparatus with entity parameters for Division 1 and Zone 0

21 21 ANSI/ISA-RP Hazardous (Classified) Location Class I, Zone 1, Group IIC INTRINSICALLY SAFE APPARATUS WITH ENTITY PARAMETERS Unclassified Location or Class I, Zone 2, Group IIC Vmax (or Ui) > Voc (or Uo) Imax (or Ii) > Isc (or Io) Pi > Po Ci + Ccable < Ca (or Co) Li + Lcable < La (or Lo) Lcable/Rcable verification see note 5 OR SIMPLE APPARATUS 3 4 G G 1 2 Ground Conductor Connections MODEL NO. POLARITY Voc or Uo (V) Isc or Io (ma) Po (mw) Ca or Co (µf) GROUP IIC GROUP IIB GROUP IIA La La/Ra Ca La La/Ra Ca La or Lo or Lo/Ro or Co or Lo or Lo/Ro or Co or Lo (mh) (µh/ω) (µf) (mh) (µh/ω) (µf) (mh) La/Ra or Lo/Ro (µh/ω) AC The maximum unclassified location voltage, Um, is 250 V ac/dc 2 Barrier ground shall be connected to a grounding electrode ANSI/NFPA 70, Articles The installation must be in accordance with the National Electrical Code, NFPA 70, Articles 504 and 505, and ANSI/ISA-RP Series Shunt Diode Barriers are Approved with connections to Class I, Zone 1 applications as AEx [ib]. Connecting AEx ia I.S. Apparatus to the 2000 Series Shunt Diode Barriers does not make the I.S. Circuit suitable for Class I, Zone 0 or Division 1 Hazardous (Classified) Locations. 5. Li may be greater than La and the cable length restrictions due to cable inductance (Lcable) can be ignored if both of the following conditions are met: La/Ra (or Lo/Ro) > Li/Ri La/Ra (or Lo/Ro) > Lcable/Rcable SAFETY BARRIER Co. OLD PORT, EAST VIRGINIA CONTROL DRAWING NO. L765 MODEL 2000 SERIES SHUNT DIODE BARRIERS Class I, Zone 1 Application Approved by: John J. Smith DWG. No.: L765 Date: 6/20/00 Rev.: B Figure 4.3b Example of control drawing for an associated apparatus with entity parameters for Zone 1

22 Hazardous (Classified) Location Class I, Zone 0, Group IIC INTRINSICALLY SAFE APPARATUS WITH ENTITY PARAMETERS Vmax (or Ui) > Voc (or Uo) Imax (or Ii) > Isc (or Io) Pi > Po Ci + Ccable < Ca (or Co) Li + Lcable < La (or Lo) Lcable/Rcable verification see note 5 OR SIMPLE APPARATUS Voc or Uo (V) Hazardous (Classified) Location Class I, Zone 1, Group IIC Note: T4 temperature code based on 60 C ambient T5 temperature code based on 40 C ambient 6400 SERIES TEMPERATURETRANSMITTERS AEx ib [ia] AEx [ia] Output Parameters AEx ib - Input Parameters See Table below Vmax (or Ui) = 30V Imax (or Ii) = 300mA Pi = 0.65W Ci = 1.2nF Li = 3.25mH Li/Ri = 45 µh/ohm 1. The installation must be in accordance with the National Electrical Code, NFPA 70, Articles 504 and 505, and ANSI/ISA- RP Series Transmitters are Approved for Class I, Zone 1 Locations. 3. Inputs of the 6400 Series Transmitters are Approved for Class I, Zone 1 applications as AEx ib. Connecting AEx [ia] Associated Apparatus or AEx ia I.S. Apparatus to the 6400 Series Transmitters does not make the I.S. Circuit suitable for Class I, Zone 0 Hazardous (Classified) Locations. 4. Outputs of the 6400 Series Transmitters are Approved with connections to Class I, Zone 0 applications as AEx [ia]. If connecting AEx ib I.S. Apparatus to the 6400 Series Transmitters the I.S. circuit is only suitable for Class I, Zone 1 or Class I, Zone 2 and is not suitable for Class I, Zone 0 Hazardous (Classified) Locations. 5. Li may be greater than La and the cable length restrictions due to cable inductance (Lcable) can be ignored if both of the following conditions are met: La/Ra (or Lo/Ro) > Li/Ri La/Ra (or Lo/Ro) > Lcable/Rcable Unclassified Location ASSOCIATED APPARATUS WITH ENTITY PARAMETERS Voc (or Uo) < Vmax (or Ui) Isc (or Io) < Imax (or Ii) Po < Pi Ca (or Co) > Ci + Ccable La (or Lo) > Li + Lcable Lcable/Rcable verification see note Series AEx [ia] Output Parameters GROUP IIC GROUP IIB GROUP IIA Isc Ca La La/Ra Ca La La/Ra Ca La La/Ra or Io Po or Co or Lo or Lo/Ro or Co or Lo or Lo/Ro or Co or Lo or Lo/Ro (ma) (mw) (µf) (mh) (µh/ω) (µf) (mh) (µh/ω) (µf) (mh) (µh/ω) ABC Co., Inc. INTRINSIC SAFETY CONTROL DRAWING FOR 6400 SERIES TEMPERATURE TRANSMITTERS AEx ib [ia] Approved by: John J. Smith DWG. No.: CD Date: 6/20/00 Rev.: B ANSI/ISA-RP Figure 4.3c Example of control drawing for a Temperature Transmitter with entity parameter, for Class I, Zone 1 locations as AEx ib and with connections to Class I, Zone 0 locations as AEx [ia].

23 23 ANSI/ISA-RP (b) Location: Intrinsically safe apparatus shall be permitted to be installed in any hazardous (classified) locations for which it has been identified. General-purpose enclosures shall be permitted for intrinsically safe apparatus. Associated apparatus shall be permitted to be installed in any hazardous (classified) location for which it has been identified, or if protected by other means permitted by Articles 501 through 503 and 505. An intrinsically safe system consists of associated apparatus in an unclassified or a Division 2 (Zone 2) location that is connected by wiring to intrinsically safe apparatus in a Division 1 (Zone 0 or Zone 1) or Division 2 (Zone 2) location. Alternatively, the intrinsically safe circuit may originate in associated apparatus suitable for, and located in, a Division 1 (Zone 1) location. Intrinsically safe apparatus that has been approved for a Division 1 location may be used in a Division 2 location of the same class and group. (See (A)(2) of the NEC.) Intrinsically safe apparatus that has been approved for a Zone 0 or Zone 1 location may be used in a Zone 2 location of the same class and group. (See (B) of the NEC.) Intrinsically safe apparatus connected to ib associated apparatus may not be used in a Class I, Zone 0 or Class I, Division 1 location, even if the intrinsically safe apparatus is rated ia. Some examples of intrinsically safe systems are given in figure A.1. Intrinsically safe apparatus should be provided with an enclosure that is suitable for the environmental conditions to which it will be exposed (such as temperature, moisture, and corrosion) Wiring Methods. Intrinsically safe apparatus and wiring shall be permitted to be installed using any of the wiring methods suitable for unclassified locations, including Chapter 7 and Chapter 8. Sealing shall be as provided in , and separation shall be as provided in Unless required by Article 504, intrinsically safe circuits need not comply with Articles 501 through 503 and 510 through 516 of the NEC (2002) and, in general, may be wired in the same manner as comparable circuits intended for use in unclassified locations. Examples are PLTC cable in cable trays, nonmetallic cables, and communication cables. Since the energy in an intrinsically safe circuit is inherently limited, no additional overcurrent protection is required in such circuits. Additional precautions should be taken to provide mechanical protection in applications involving vibration, motion, impacts, etc Separation of Intrinsically Safe Conductors. (A) From Nonintrinsically Safe Circuit Conductors. (1) Open wiring. Conductors and cables of intrinsically safe circuits not in raceways or cable trays shall be separated at least 50 mm (2 in.) and secured from conductors and cables of any nonintrinsically safe circuits.

24 ANSI/ISA-RP Exception: Where either (1) all of the intrinsically safe circuit conductors are in Type MI, or MC cables or (2) all of the nonintrinsically safe circuit conductors are in raceways or Type MI, or MC cables where the sheathing or cladding is capable of carrying fault current to ground. (2) In raceways, cable trays, and cables. Conductors of intrinsically safe circuits shall not be placed in any raceway, cable tray, or cable with conductors of any nonintrinsically safe circuit. Exception No. 1: Where conductors of intrinsically safe circuits are separated from conductors of nonintrinsically safe circuits by a distance of at least 50 mm (2 in.) and secured, or by a grounded metal partition or an approved insulating partition. Braided or aluminum/polyester shielding is not considered suitable for a grounded metal partition. Cable jackets normally are not considered suitable for an insulating partition. FPN: No. 20 gauge sheet-metal partitions 0.91 mm ( in.) or thicker are generally considered acceptable. Exception No. 2: Where either (1) all of the intrinsically safe circuit conductors or (2) all of the nonintrinsically safe circuit conductors are in grounded metal-sheathed or metal-clad cables where the sheathing or cladding is capable of carrying fault current to ground. FPN: Cables meeting the requirements of Articles 330 and 334 are typical of those considered acceptable. (3) Within enclosures. (a) Conductors of intrinsically safe circuits shall be separated at least 50 mm (2 in.) from conductors of any nonintrinsically safe circuits or as specified in (A)(2). (b) All conductors shall be secured so that any conductor that might come loose from a terminal cannot come in contact with another terminal. FPN No. 1: The use of separate wiring compartments for the intrinsically safe and nonintrinsically safe terminals is the preferred method of complying with this requirement. FPN No. 2: Physical barriers such as grounded metal partitions or approved insulating partitions or approved restricted access wiring ducts separated from other such ducts by at least 19 mm (3/4 in.) can be used to help ensure the required separation of the wiring. Care should be taken in the layout of terminals and the wiring methods used to prevent contact between intrinsically safe and nonintrinsically safe circuits. Some layouts e.g., when terminals arranged one

25 25 ANSI/ISA-RP above another do not provide adequate separation if a wire should become disconnected. In these cases, additional precautions (such as tie-downs) are necessary. Clearance between ungrounded terminals and grounded metal should be at least 3 mm (0.125 in.). A partition may be used to segregate terminals and should extend close enough to the enclosure walls to effectively separate the wiring on either side of the partition. Alternatively, the partition need only extend far enough beyond the terminals to provide 50 mm (2 in.) spacing between intrinsically safe and nonintrinsically safe terminals if the wiring is secured to maintain the required separation. When several devices having both intrinsically safe and nonintrinsically safe terminals are mounted in the same enclosure, attention must be given to the separation of circuits. An acceptable method of separation is shown in figure A-2. Separate wireways are often used to provide greater assurance that separation of wiring will be maintained. Wire lacing, wire ties, or equivalent fasteners are also acceptable methods of maintaining the 50 mm (2 in.) separation. Plug-and-socket connectors used to connect intrinsically safe circuits in an unclassified location either should not be interchangeable with any other plugs or sockets or should be identified in a way that minimizes the possibility of such interchange. (B) From Different Intrinsically Safe Circuit Conductors. Different intrinsically safe circuits shall be in separate cables or shall be separated from each other by one of the following means. (1) The conductors of each circuit are within a grounded metal shield. (2) The conductors of each circuit have insulation with a minimum thickness of 0.25 mm (0.01 in.). Exception: Unless otherwise identified. Clearance between terminals for the connection of different intrinsically safe circuits should be at least 6 mm (0.25 in) Grounding. (A) Intrinsically Safe Apparatus, Associated Apparatus, and Raceways. Intrinsically safe apparatus, associated apparatus, cable shields, enclosures and raceways, if of metal, shall be grounded. NOTE Supplementary bonding to the grounding electrode may be needed for some associated apparatus, e.g., zener diode barriers, if specified in the control drawing. The integrity of a shunt diode intrinsic safety barrier depends on the effective shunting of the ignitioncapable electrical current back to the source (to ground). It is the intent of the following recommendations to ensure that the methods used to connect barriers to ground provide a high integrity, low-resistance return path to the source of the fault current. A separate insulated connection to a grounding electrode will minimize fault currents from other equipment elevating

26 ANSI/ISA-RP the I.S. ground. Careful consideration should be given to the grounding electrode system(s) to which potential sources of supply and intrinsically safe apparatus are connected. This will enable a determination of whether shunt diode barriers are appropriate (see figure 4.7) and, if so, selection of a grounding electrode. EXCEPTION: The equipment grounding conductor may be used as the intrinsic safety grounding conductor only if potential ground-fault current from other equipment that is sharing the AC grounding conductor will not cause an unsafe voltage differential between the grounding electrode and a grounded conductor of an intrinsically safe circuit. Examples of installations not requiring a separate intrinsic safety grounding conductor may include flowmeters with intrinsically safe transducers, consoles with intrinsically safe keyboards, and recorders with intrinsically safe inputs where there is an equipotential bond between the barrier ground and grounded metal parts that the intrinsically safe circuit may contact. The barrier-grounding terminal must be connected to the grounding electrode. Where there are multiple barriers, the individual grounding terminals may be collected at a common point such as a barrier bus (see figures 4.4 through 4.6). The common point or the grounding terminal on a single barrier must be connected to the grounding electrode using an insulated conductor no smaller than 12 AWG (American Wire Gauge). The wires between individual barriers and the common point may be smaller than 12 AWG. The conductor to the grounding electrode should be identified at both ends to differentiate it from other ground conductors. The conductor must be protected from damage as required by NEC (C). All grounding path connections should be secure, permanent, visible, and accessible. The grounding path resistance from the farthest barrier to the grounding electrode should not exceed 1 ohm. More than one barrier bus may use the same grounding conductor(s), provided the buses are interconnected in such a way that disconnection of one barrier bus does not result in loss of ground to the other buses. Figure 4.4 shows a grounding system in which a separate intrinsic safety ground conductor is connected directly between the barrier bus and the grounding electrode.

27 27 ANSI/ISA-RP HAZARDOUS LOCATION INTRINSIC SAFETY BARRIERS CABINET L N SERVICE DISCONNECT BREAKER PANEL NEUTRAL FIELD DEVICE SUPPLY COMMON GROUND BARRIER BUS REQUIRED INTRINSIC SAFETY GROUNDING CONDUCTOR OPTIONAL RECOMMENDED REDUNDANT GROUNDING CONDUCTOR AC GROUNDING CONDUCTOR GROUNDING ELECTRODE SYSTEM GROUNDING ELECTRODE NOTES: I.S. GROUNDING CONDUCTOR INSULATED. BARRIER BUS INSULATED FROM OTHER GROUNDED METAL. SUPPLY COMMON INSULATED FROM OTHER GROUNDED METAL. Figure 4.4 Separate intrinsic safety grounding conductor with field device bonded to same grounding electrode system

28 ANSI/ISA-RP Figure 4.5 shows an alternate grounding system in which the separate intrinsic safety ground conductor is connected between the supply common bus and the grounding electrode. HAZARDOUS LOCATION INTRINSIC SAFETY BARRIERS CABINET L N SERVICE DISCONNECT BREAKER PANEL NEUTRAL FIELD DEVICE BARRIER BUS REQUIRED INTRINSIC SAFETY GROUNDING CONDUCTOR OPTIONAL RECOMMENDED REDUNDANT I.S. GROUNDING CONDUCTOR SUPPLY COMMON GROUND REQUIRED INTRINSIC SAFETY GROUNDING CONDUCTOR OPTIONAL RECOMMENDED REDUNDANT I.S. GROUNDING CONDUCTOR AC GROUNDING CONDUCTOR GROUNDING ELECTRODE SYSTEM GROUNDING ELECTRODE NOTES: I.S. GROUNDING CONDUCTOR INSULATED. BARRIER BUS INSULATED FROM OTHER GROUNDED METAL. SUPPLY COMMON INSULATED FROM OTHER GROUNDED METAL. Figure 4.5 Alternate separate intrinsic safety grounding conductor with field devices bonded to same grounding electrode system

29 29 ANSI/ISA-RP Figure 4.6 shows an alternate grounding system in which the supply common bus and the barrier bus are connected to a separate master barrier bus bar that is used to interconnect the barrier buses from several cabinets. HAZARDOUS LOCATION INTRINSIC SAFETY BARRIERS CABINET L N SERVICE DISCONNECT BREAKER PANEL NEUTRAL FIELD DEVICE BARRIER BUS INTRINSIC SAFETY BARRIERS SUPPLY COMMON REQUIRED AND OPTIONAL I.S. GROUNDING CONDUCTORS MASTER BARRIER BUS REQUIRED INTRINSIC SAFETY GROUNDING CONDUCTOR OPTIONAL RECOMMENDED REDUNDANT GROUNDING CONDUCTOR GROUND AC GROUNDING CONDUCTOR BARRIER BUS GROUNDING ELECTRODE SYSTEM GROUNDING ELECTRODE NOTES: I.S. GROUNDING CONDUCTOR INSULATED. BARRIER BUS INSULATED FROM OTHER GROUNDED METAL. SUPPLY COMMON INSULATED FROM OTHER GROUNDED METAL. Figure 4.6 Separate intrinsic safety grounding conductor with field device bonded to same grounding electrode system