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Electrical Engineering Handbook

Electrical Engineering Handbook

BECHTEL CORPORATION ELECTRICAL ENGINEERING HANDBOOK COMPARISON OF IEC- ANSI/NEMA Prepared by : M McLaughlin (LOEU) Special Recognition to: B. Hibbett (LOEU) M. Donati (HOEU) 0 A 13-Jan-00 12-NOV-99 REV. DATE LORO ISSUED FOR CORPORATE USE ISSUED FOR COMMENT REASON FOR REVISION MM MM BY BP BP CHECK BECHTEL CORP KGH KGH APPR REV 000 ELECTRICAL ENGINEERING HANDBOOK 3DG-E15-00002 COMPARISON OF IEC – ANSI/NEMA Page 1 of 44 E BECHTEL CORPORATION E&C CENTRAL FUNCTIONS – ENGINEERING ELECTRICAL ENGINEERING HANDBOOK COMPARISON OF IEC – ANSI/NEMA 3DG-E15-00002, Revision 000

CONTENTS 1. 2. 3. 4 PURPOSE ………………………………………………………………………………………… 5 SCOPE …………………………………………………………………………………………….. 5 GENERAL ………………………………………………………………………………………… 5 ENGINEERING PRACTICES ………………………………………………………………. 5 4. 1 4. 2. 4. 3. 4. 4. 4. 5. 4. 6. 4. 7 4. 8 4. 9 4. 10 5. 5. 1. 5. 2. 5. 3. 5. . 6. 6. 1. 6. 2. 6. 3. 6. 4. 6. 5. 6. 6. 6. 7. 6. 8. General …………………………………………………………………………………… 5 Systems Design ……………………………………………………………………….. 6 One-Line Diagrams …………………………………………………………………. 12 Bechtel Design Guides and Specifications …………………………………. 13 Codes and Standards………………………………………………………………. 3 Hazardous Area Classification ………………………………………………….. 15 Substations ……………………………………………………………………………. 21 Switchgear and MCCs……………………………………………………………… 22 Earthing / Grounding ……………………………………………………………….. 24 Cathodic Protection …………………………………………………………………. 25 Electrical Load Database System (ELDS)…………………………………… 5 SetRoute ……………………………………………………………………………….. 25 Electrical Transient Analysis Programme (ETAP) ………………………… 25 Power Tools (CAPTOR) …………………………………………………………… 26 Power Supply Layouts……………………………………………………………… 26 Lighting Layouts ……………………………………………………………………… 27 Emergency Lighting…………………………………………………………………. 7 Distribution Boards ………………………………………………………………….. 28 Terminations ………………………………………………………………………….. 28 Materials Certification………………………………………………………………. 28 Power and Control Cables ……………………………………………………….. 28 Instrumentation and Communication Cable ………………………………… 29 BECHTEL STANDARD APPLICATIONS (BSAPS) ………………………………. 5 DESIGN PRACTICES……………………………………………………………………….. 26 E 6. 9. 6. 10. 6. 11. 6. 12. 6. 13. 6. 14. 6. 15. 6. 16. 6. 17. 6. 18. 7. 7. 1 7. 2. 7. 3. 7. 4. 7. 5. 7. 6. 7. 7. 7. 8. 7. 9. 7. 10. 7. 11. 7. 12. 7. 13. 8. 9. Cable Glands and Terminations ………………………………………………… 29 Cable Tray / Ladder rack………………………………………………………….. 30 Ducts and Conduit…………………………………………………………………… 1 Motor Control Stations and Switches …………………………………………. 32 Junction and Terminal Boxes ……………………………………………………. 32 Lighting Fittings ………………………………………………………………………. 33 Socket Outlets / Receptacles ……………………………………………………. 33 Earthing / Grounding Materials………………………………………………….. 33 Heat Tracing and Winterisation …………………………………………………. 4 Cathodic Protection Materials …………………………………………………… 34 Terms and Nomenclature…………………………………………………………. 34 Mechanical protection degree of enclosures ……………………………….. 35 Transformers………………………………………………………………………….. 36 Switchgear …………………………………………………………………………….. 37 Circuit Breakers………………………………………………………………………. 9 Isolators & Switches, Disconnects & Interrupters…………………………. 39 Contactors……………………………………………………………………………… 40 Electric Motors ……………………………………………………………………….. 40 Motor Starters ………………………………………………………………………… 41 Bus-Ducting/Bus-Way ……………………………………………………………… 42 Relays …………………………………………………………………………………… 2 Reactors………………………………………………………………………………… 43 Equipment Accommodation, Substations and Equipment Rooms ….. 43 EQUIPMENT……………………………………………………………………………………. 34 COST CONSIDERATIONS………………………………………………………………… 43 REFERENCES ………………………………………………………………………………… 45 APPENDICES A Comparison of IEC and ANSI Protective Device Symbols …………….. 6 B Comparison of Cable Construction………………………………….. …. 53 C Alternative Design Codes ANSI/NEMA VS IEC – Electrical Pricing Comparison……………………………………….. …… 60 ATTACHMENTS IEC ANSI/NEMA Price Comparison……………………………………. Graphs. xls A Comparison of North American (ANSI) and European (IEC) Fault Calculations Guidelines……………………………………………Ref01. pdf Short-Circuit Current Calculation: A Comparison Between Methods of IEC and ANSI Standards Using Dynamic Simulation as Reference………………………………………… …….. Ref02. pdf Why US/European Switchgear Differences are so critical………… Ref03. pdf E Summary of Comparison between ANSI and IEC Standards For Power Transfoemers……………………………….. … Ref04. pdf A Comparison of ANSI and IEC Standards For Switchgear Assemblies……………………………………… ….. Ref05. pdf Comparison of ANSI/IEEE and IEC Requirements For Metal-Clad Switchgear………………………………………… ….. Ref06. pdf Issues and Answers…………………………………………… … … Ref07. pdf IEC and NEMA: Questions and Concerns…………………………… Ref08. pdf Comparison of IEC and NEMA/IEEE Motor Standards, Psrt I…… . Ref10. pdf Comparison of IEC and NEMA/IEEE Motor Standards, Psrt II…… . Ref11. df A Technical Comparison of ANSI & IEC Standards for Medium Voltage Circuit Breakers……………………………………… Ref12. pdf Comparing ANSI and IEC Power Circuit Breaker Current-Rating Standards………………………………………………. Ref13. pdf Voltage and Standards in the World……………………………….. …. Ref14. pdf E BECHTEL – ELECTRICAL ENGINEERING HANDBOOK COMPARISON OF IEC – ANSI/NEMA 1. PURPOSE Page 5 of 44 To provide guidance, in the execution of electrical work, to Bechtel US personnel on International projects where IEC rules apply, and to Bechtel EAMS personnel on International projects where ANSI/NEMA rules apply. . SCOPE Covers all aspects of electrical work including engineering, design, equipment selection, and installation. 3. GENERAL There are two major authorities which govern electrical installations, in the USA, ANSI/NEMA/NFPA 70, and in Europe, IEC/CENELEC. In addition there may be local regulations in force which also have to be taken into account. It is the intent of this “Handbook” to provide a ready access to comparisons, and equivalents, between these two standards for the guidance of Bechtel engineers. 4 ENGINEERING PRACTICES 4. 1 General 4. 1. Terms and Nomenclature A Brief comparison of some of the nomenclature used for design with regard to both European and US practices are given below. TERMS AND NOMENCLATURE – ENGINEERING INTERNATIONAL Earthing Current Rating Cable Drum Raceway Steel Wire / tape armour to IEC 502 Cable Screen Cable Sheath Cable Glands Cable Gland Entry Size Cable Rack (Ladder Rack) Cable Tray (Cable Channel) Lighting Fittings Earth Rod USA Grounding Ampacity Cable Reel Raceway Metal Clad Cable Shield Cable Jacket Terminators, Cable Ready Connectors Hub Size Cable Tray (Ladder Cable Tray) Channel Lighting Fixtures or Luminaires Ground Rod

Table 4. 1 4. 1. 2 International Units of Measurement E BECHTEL – ELECTRICAL ENGINEERING HANDBOOK COMPARISON OF IEC – ANSI/NEMA Page 6 of 44 The IEC uses the metric (or SI) system of units of measurement. There are numerous publications available in the use and conversion from US units to metric units. American National Metric Council API Publication 2564 Manual of Petroleum Measurement Standards Chapter 15 – Guidelines for the Use of Units (SI) in the Petroleum and Allied Industries. ASME Guide SI-1 Orientation and Guide for the Use of SI (Metric) Units 4. . Systems Design 4. 2. 1. Voltage Levels A list of voltages commonly used in both types of engineering practice is given below in table 4. 2a. 100V – 1000V, AC systems having a nominal voltage between 100Volts and 1000Volts inclusive, and related equipment. IEC 60038 Amendment 1 STANDARD VOLTAGES 100V – 1000V Three phase four wire or three wire systems Nominal Voltage (V) 50 Hz 60 Hz 120/208 240 230 / 400 277/480 400 / 690 480 347/600 1000 600 Single phase Three wire systems Nominal Voltage (V) 120 / 240 (*) – ANSI/NEMA EQUIVALENTS (C. 84. –1995) 60 Hz Three phase four wire or three wire systems Nominal Voltage (V) 120 / 208 240 277/480 480 600 Table 4. 2A (*) The same nominal voltage applies to Single phase , Three wire US systems E BECHTEL – ELECTRICAL ENGINEERING HANDBOOK COMPARISON OF IEC – ANSI/NEMA Page 7 of 44 IEC 60038, 1kV – 35kV, AC systems having a nominal voltage between 1000Volts and 35,000Volts inclusive, and related equipment. SERIES I SERIES II (50Hz – 60Hz) (60Hz ANSI/NEMA) (ANSI C37. 06) Highest voltage for equipment (kV) 3. 6(1) 7. 2 12 17. 5 24 36 40. Nominal system voltage (kV) 3. 3(1) 6. 6(1) 11 22 33 3(1) 6(1) 10 15 20 35 Rated Maximum Voltage (kV – rms) 5. 0 15. 0 15. 0 15. 0 27. 0 38. 0 Nominal system voltage (kV) 4. 16(1) 12. 47 13. 2 13. 8 27 34. 5 – Table 4. 2B Notes 1. Not to be used for public distribution systems. In [16] a detailed table of the various system voltages and standards utilised in the different world wide counties is provided. 4. 2. 2. Frequency Generally, power generated to IEC standards supplied at 50Hz and power generated to ANSI-NEMA/NFPA 70 standards at 60Hz.

Machines, transformers, and other equipment have different reactances at 50Hz and 60Hz, such that interchange may not be possible, even if the voltage range is the same. 4. 2. 3. Harmonics Each set of standards specifies different levels of harmonics which may be generated back to the supply utility. Current practice in Bechtel London is to limit the harmonics in accordance with UK Electricity Council Standard G5/3. In the US harmonics are limited to IEEE 519. 4. 2. 4. Permitted Tolerances New guidelines have been issued for permitted voltage tolerances in accordance with IEC 60038 Amendment 1.

As we are in the middle of a transition period where the current nominal voltages of 220/380V and 240/415V are evolving towards 230/400V, the guideline is not strictly in E BECHTEL – ELECTRICAL ENGINEERING HANDBOOK COMPARISON OF IEC – ANSI/NEMA Page 8 of 44 place until a recommended time of 2003, when the tolerances applicable should be 230/400V ± 10%. PERMITTED TOLERANCES IEC 230/400 ± 10%. 480V ± 10%. ANSI/NEC Table 4. 2C 4. 2. 5. Short Circuit Levels Both the manner in which short-circuit levels are defined and the standard short-circuit ratings are different when comparing IEC and ANSI-NEMA/NFPA 70 standards [1 & 2].

The ANSI standard is not directly addressed to the calculation of short-circuit currents but its aim is to choose as well as possible the circuit breaker rating. The IEC 60909 is not particularly oriented to breaker sizing, but rather to the calculation of short-circuit currents. London office practice is to use the calculated fault levels (including DC component) as an input to the selection of switchboard/circuit breaker sizing. Current Bechtel standard computer program for calculating short circuit is ETAP. The program performs the short circuit calculation for IEC 60909 and ANSI in accordance to IEEE Red Book.

SHORT-CIRCUIT LEVEL STANDARDS AND DIFFERENCES IEC IEC 60909 – Short-Circuit Current Calculation in Three-Phase A. C. Systems Main defining parameters are – • ip – Peak value • Ib – Symmetrical short-circuit breaking current at the instant tm of contact separation of the first pole of a switching device • iDC – Aperiodic DC component Other parameters defined by IEC 60909 • Ik” – Initial rms symmetrical component • Ib asym – rms asymmetrical short-circuit breaking current • Ik – rms steady state short-circuit current.

IEC 60909 calculates ip IEC 60909 does not endorse the concept of the single X/R ratio, but more than one X/R ratio has to be considered when independent sources feed the fault. This technique is applied on superposition principles. ANSI/IEEE ANSI/IEEE C37. 010-1979 (High Voltage Applications) Defining parameters are – • First half cycle or withstand rating (bracing) (ip ) • Interrupting rating (Ib ) ANSI standard does not directly consider this quantity, but allows for the calculation of it.

ANSI standard allows the use of a simplified calculation with one X/R ratio. E BECHTEL – ELECTRICAL ENGINEERING HANDBOOK COMPARISON OF IEC – ANSI/NEMA Page 9 of 44 SHORT-CIRCUIT LEVEL STANDARDS AND DIFFERENCES (cont’d) IEC AC decay is modelled by considering machine type, size, speed, breaker interrupting time and proximity to fault. IEC guidelines classify faults as “near to generator” (ac decrement present) or “far from fault” (no ac decrement).

IEC 60909 requires motor contribution to be taken into account only for near-to-generator faults and permits neglect of such contributions under defined circumstances IEC 60909 allows the calculation of the symmetrical component Ib and shows the value of the asymmetrical component Ib asym Multiplying factors be applied to pre-fault voltage to account for transformer taps, system loads and shunts Initial fault current is defined as the prospective fault current available at the fault point at the onset of the fault (zero time) IEC 60909 explicitly includes the effect of AVR action.

Induction motor contribution is based on the starting current and motor X/R ratio. ANSI/NEMA ANSI guidelines allow for the used of generator decrement curves to calculate AC decay, ANSI guidelines classify the fault as “local” or “remote” by quantifying only generator contribution to the fault. ANSI C37-010 neglects motor contribution on utility systems and only requires induction motor contribution to the close and latch rating at substations supplying industrial loads. Not required for the break rating. ANSI standard considers only the breaker symmetrical component. . 0 pu pre-fault voltage. Usually Bechtel Houston uses 1. 05 factor for short circuit calculation and 0. 95 for voltage drop calculation First cycle symmetrical currents defined as the fault currents immediately after fault initiation. ANSI C37-010 does not consider this. Induction motor contribution is based on sub-transient reactance multiplied by a factor. IEC and ANSI differ in their treatment of generator impedances and generator X/R ratios to be used, which may have a significant effect on the fault levels calculated (refer to individual standards).

IEC does not recognise any change in rated ANSI permits an increase in the fault level capacity if a circuit breaker is operated at ratings if the circuit breaker is operated at below its maximum voltage voltages below maximum rated value. Table 4. 2D The results and comparison of a sample calculation carried out to both standards are given in [2]. 4. 2. 6. Transformer Ratings The main standards defining requirements for transformers are as shown in section 4. 5 Codes and Standards. The main differences in transformer applications between the two sets of standards are as defined below

E BECHTEL – ELECTRICAL ENGINEERING HANDBOOK COMPARISON OF IEC – ANSI/NEMA Page 10 of 44 It is important to note that machines, transformers and other equipment present different reactances at 50 Hz than at 60 Hz, such that direct interchange may not be possible, even if voltage range is acceptable. TRANSFORMERS IEC For transformers up to 10 MVA, values of rated power roughly follow the R-10 series [3] given in ISO 3 (1997), preferred numbers : (…100, 125, 160, 200, 250, 315, 400, 500, 630, 800, 1000, 1250, etc. ) IEC rating includes the losses of the transformer i. e.

MVA rating is the input power. International practice commonly uses sealed tank transformers up to approximately 1600 kVA and conservator type for larger transformers International practice commonly uses dry type transformers up for lower ratings (typically up to about 1600 kVA). Shall be capable of sustaining a maximum of 105% rated Volts/Hz continuously without damage IEC gives no requirement for power factor or direction of power flow. Tolerances applicable to transformer nominal impedance as follows – • Transformers with a specified nominal impedance (on the principal tapping) of ? 0% have an allowable tolerance ± 7. 5% • Transformers with a specified nominal impedance (on the principal tapping) of < 10% have an allowable tolerance ± 10% Single cooling rating which corresponds to the cooling method used at the top power rating. Cooling method defined as follows :• Oil natural, air natural – ONAN • Oil natural, air forced – ONAF • Oil forced, air forced – OFAF Specifies that monthly average ambient temperature over a given year shall not exceed 30 deg C and the yearly average shall not exceed 20 deg C.

One method for determining winding hotspot of transformers Thermal ageing and loading guide is IEC 60354. IEC 60354 does not recognise any temperatures above 150-160 deg C. Chopped wave insulation impulse test is not mandatory ANSI/NEMA Reference ANSI / NEMA C57 standard for power and distribution transformers, Standard ratings for different cooling methods OA / FA 55 / 650 C, and for standard impedance. ANSI rating excludes the losses of the transformer i. e. MVA rating is the output power.

American typical common practice in P&C applications is to use sealed tank transformers up to 15-20 MVA and conservator type for larger transformers. Dry type transformers commonly utilised for lighting or small VSDs. Also used for unit substations (ventilated dry type transformer). Shall sustain 110% Volts/Hz at no-load and shall be able to deliver rated power at 10% of the rates secondary voltage at a power factor of at least 80% without overheating. ANSI standards state that transformers shall be for step-down operation unless otherwise specified.

Allowable tolerance for the impedance of liquid filled transformers is ± 7%. “Triple” cooling rating Cooling method defined as follows :• Oil natural, air natural – OA • Oil natural, air forced – OA/FA • Oil forced, air forced – FOA (and with directed oil flow in the windings – ODAF) Specifies that average temperature for any 24 hour period shall not exceed 25 deg C for water cooled and 30 deg C for air cooled.. Several methods of determining hotspot [4]. Thermal ageing and loading guide is IEEE Std. 756. IEEE Std 756 recognises temperatures up to 180 deg C. Chopped wave insulation impulse test is mandatory. E

BECHTEL – ELECTRICAL ENGINEERING HANDBOOK COMPARISON OF IEC – ANSI/NEMA Asymmetry factor for short-circuit withstand is a maximum of 2. 5 Page 11 of 44 Asymmetry factor for short-circuit withstand is 2. 7 TRANSFORMERS (cont’d) IEC ANSI/NEMA The ANSI standard gives available short-circuit power for particular voltage classes of class III and IV transformers which are approximately 3 times higher than the IEC values for the same voltage level Number of shots of short-circuit withstand Number of shots of short-circuit withstand current is 3 (all shots fully offset) current is 6 (first two shots are fully offset).

Duration of shots is 0. 5 seconds of category I Duration of shots is at least 0. 25 seconds only) Table 4. 2E 4. 2. 7. Cable Derating Factor Calculations In European and US practice, cabling methods differ fairly widely. This ranges from materials of construction to methods of installation and derating factors. European (British) practice in P&C applications predominantly calls for XLPE insulated, armoured cable to be run on cable ladder or tray. US practice predominantly calls for Tray Cable (PVC, PE, EPR, XLPE or PILC insulated) to be run in cable ladder tray and drops to the user in conduit. Power cables are shielded.

CABLE DERATING FACTOR/AMPACITY CALCULATIONS IEC IEC 287 IEC 364-5-523 (low voltage unarmoured) ERA 69-30 (UK) BS 7671 Cable de-rating factors normally taken from • IEC 60287 • IEC 60364 (BS 7671 in UK) • ERA 69-30 (UK) Publications Correction Factors Required for : Ambient or Ground Temperature – Ground Thermal Resistivity Grouping – Current Harmonics (only if harmonic levels are excessive) These factors are based on the use of armoured cable in air or direct buried – Normal International Practice. NEMA/NFPA 70 NFPA-70 National Electric Code IEEE 835-1994 Cable de-rating factors normally taken from NFPA-70 National Electric Code

Correction Factors : Ambient or Ground Temperature – Soil Thermal Resistivity No. of conductors in conduit – Current Harmonics (only if harmonic levels are excessive) These factors are based on the use of TC cables in air , direct buried or in duct banks. Table 4. 2F E BECHTEL – ELECTRICAL ENGINEERING HANDBOOK COMPARISON OF IEC – ANSI/NEMA Page 12 of 44 4. 2. 8. Typical XLPE HV 3 Core Power Cable Ratings, 3. 3kV – 33kV XLPE HV 3 CORE POWER CABLE RATINGS, 3. 3kV – 33kV IEC Cross Sectional Area mm2 16 25 35 f50 70 95 120 150 185 240 Nominal Rating @ 150C A 110 140 170 210 255 300 340 380 430 490 Equivalent Rating @ 400C(5) A

ANSI/NEMA/NFPA 70 Nearest Equivalent Size AWG / kcmil #6 AWG #4 AWG #2 AWG #1/0 AWG #2/0 AWG #3/0 AWG #250,4/0 kcmil #350 kcmil #350 kcmil #500 kcmil Equivalent Ampacity @ 1040F (400C) [NFPA 70 table 310-67 MV-90 5001-35000V 100 130 170 225 260 300 380 470 470 580 97 123 150 185 224 264 299 334 378 431 Table 4. 2G Notes : 1. Nominal Ratings vary slightly with different manufacturers, cable composition, lead sheaths and voltage. 2. Site Cable ratings vary with the applied de-rating factor – ambient, grouping, depth, soil thermal resistivity. 0 0 3. XLPE allows higher maximum operating temperature (90 C) than PVC (70 C). 4.

In the USA, EPR and XLPE is used for medium voltage cables (>600V) with operating temperature of 0 0 90 C and 105 C. The ampacity values above are taken from NFPA-70 table 310-67. 0 5. Derating factor of 0. 88 for cable installed in air at ambient temperature of 40 C. 4. 3. One-Line Diagrams 4. 3. 1. Standard Electrical Symbols Cross references for typical standard symbols used by Bechtel for International and USA projects are contained in the following corporate Design Guides : 3DG-E13E-002 3DG-E13E-003 Symbols for One Line and Schematic Diagrams (International Projects) Standard Relay Device Function Symbols (International Projects)

Reference appendix A for direct comparison of the IEC protective device symbols with ANSI/IEEE device numbers. E BECHTEL – ELECTRICAL ENGINEERING HANDBOOK COMPARISON OF IEC – ANSI/NEMA Page 13 of 44 4. 4. Bechtel Design Guides and Specifications Bechtel LORO Design Guides Library can be found on the BecWeb at – http://147. 1. 64. 121/rsbin/RightSite. dll/formexec? DMW_INPUTFORM=becreflon/library01&OB JECTID=0b00101d80000e0d&OFFCODE=E&OFFNAME=London Bechtel LORO Specification Library can be found on the BecWeb at http://147. 1. 64. 121/rsbin/RightSite. dll/formexec?

DMW_INPUTFORM=becreflon/library01&OB JECTID=0b00101d80000f9a&OFFCODE=E&OFFNAME=London Bechtel Houston Design Guides Library can be found on the BecWeb at – http://147. 1. 193. 209/rsbin/RightSite. dll/formexec? DMW_INPUTFORM=becrefentity/library01& OBJECTID=0b00101d80000e0d&entity=HOEU Bechtel Houston Specification Library can be found on the BecWeb at http://147. 1. 108. 37/rsbin/RightSite. dll/formexec? DMW_DOCBASE=becref&OBJECTID=0b00 101d80000f9a&DMW_DOCBASE=becref&DMW_INPUTFORM=becref entity/library01&ENTITY=HOEU Bechtel Frederick Design Guides Library can be found on the BecWeb at http://becwebga. echtel. com/control/elect/ Bechtel Houston Specification Library can be found on the BecWeb at http://becwebga. bechtel. com/control/elect/ 4. 5. Codes and Standards E BECHTEL – ELECTRICAL ENGINEERING HANDBOOK COMPARISON OF IEC – ANSI/NEMA Page 14 of 44 A list of relevant codes and standards for both types of engineering practice is given below EQUIPMENT STANDARDS ITEM Generators IEC / CENELEC 60034; 60072; 60085 US ANSI C50. 5; ANSI C50. 0; ANSI C50-12; IEEE 115; IEEE 126; NEMA MG-1; NEMA MG-2; OSHA ANSI/IEEE C57; NFPA 70; NEMA ICS 6 NEMA ST-20 NEMA MG 1&2; API 541; API 546; IEEE 841 NEMA MG 1&2; API 541; API 546; IEEE 841 NEMA MG 172; API 541; API 546; IEEE 841 NEMA MG 1&2; API 541; API 546; IEEE841 NEMA MG 1&2; API 541; API 546; IEEE 841 Oil Filled Transformers Dry Type Transformers Motors (TEFC) Motors (Ex-n) Motors (Ex-e) Motors (Ex-d) Motors (Ex-p) HV Gas Insulated Switchgear MV Switchgear (Metal Clad Type) LV Switchgear LV Draw-Out MCC LV Fixed MCC LV Distribution Boards LV Switch Racks DC UPS AC UPS Battery Set 0076; 60137; 60156; 60214; 60296; 60354; 60542; 60551; 60590; 60616; 60722 60726; 60905 60034; 60072 60034; 60072; 60079; 60085; EN 50014 60034; 60072; 60079; 60085; EN 50014; EN 50019 60034; 60072; 60079; 60085; EN 50014; EN 50018 60034; 60072; 60079; 60085; EN 50014; EN 50016 60517; 60518; 60694 60056; 60129; 60185; 60186; 60255; 60265; 60282; 60298; 60420; 60466; 60470; 60529; 60632; 60644; 60694; 60932 60185; 60186; 60255; 60269; 60439; 60446; 60529; 60694; 60947 60185; 60186; 60255; 60269; 60439; 60446; 60529; 60694; 60947 60185; 60186; 60255; 60269; 60439; 60446; 60529; 60694; 60947 60185; 60186; 60255; 60269; 60439; 60446; 60529; 60947 60079; 60186; 60255; 60269; 60439; 60446; 60529; 60947 60146; 60269; 60478; 60947 60146; 60269; 60947 60623; 60896 ANSI Z55. 1; ANSI 57. 13; NEMA ICS 1,2,4,6; NFPA 70; ANSI/IEEE C. 7; NEMA SG 2,4&5 ANSI/IEEE C37; ANSI C57. 13; ANSI/IEEE 47; NEMA SG-3&5; NFPA 70; UL1558 NEMA ICS 1,2,6; ANSI Z55. 1; NFPA 70; NEMA AB 1 NEMA PB 1 IEEE 74; NEMA ICS 1,2,3,4,6; ANSI Z55; NFPA 70 NEMA PE-5&7 ANSI/IEEE 446; NEMA PE-1 IEEE485 E BECHTEL – ELECTRICAL ENGINEERING HANDBOOK COMPARISON OF IEC – ANSI/NEMA Page 15 of 44 EQUIPMENT STANDARDS (cont. ) ITEM AC Variable Speed Drive IEC / CENELEC 60034-17; 60146; 60269; 60947 US IEEE 519; IEEE 59; NEMA ICS 3. 1; IEEE 444; ANSI MC 96. 1; IEEE 85; IEEE 112; NEMA MG-1; ANSI C50. 41; ANSI C37. 30; ANSI C37. 21; ANSI C37. 23; NEMA SG-5 Solid State Motor Soft Start Power Factor Compensation System HV Power cables LV Power cables 0146; 60255; 60269; 60439; 60446; 60529; 60730-2-10; 60947 60269; 60282; 60439; 60529; 60549; 60831; 60871; 60931; 60996 60055; 60141; 60840 60189; 60227; 60228; 60245; 60331; 60332; 60724 60245 60332, 60502, 60724; 60986, 60183 MV Power Cables MI Cables Optic Fibre cables Reactors Line Traps Outlets & Sockets Conduits PVC Sleeves Luminaries 60702 60794 60289; 60722 60353 60309 60423; 60614; 60981 60684 60598; 60662 NFPA 70 ICEA S-66-524; ICEA S-68-516; ICEA S-73-532; ICEA T- 30520; IEEE 383; IEEE 1202; NFPA 70; ASTM B3, B8, B33, B496 ICEA S-66-524; ICEA S-68-516; ICEA T-30-520; NFPA 70; UL 1072; AEIC CS5; AEIC CS6; IEEE 1202; ASTM B3, B8, B33, B496 NFPA 70 NFPA 70 ANSI C57 NFPA 70 NFPA 70 NFPA 70 NFPA 70 Table 4. 5A 4. 6. Hazardous Area Classification 4. 6. 1.

Area Classification Definitions : International Electrotechnical Commission (IEC) The commonly accepted hazardous area classification code is that of the Institute of Petroleum, the IP Code Part 15. This is used and recognised by all the major oil companies, EU regulatory bodies, and insurers. For petrochemical plants in USA, hazardous area classification is based on API RP-500 for the Class & Division methods and on API RP-505 for Zone method. NFPA 497 is also utilised, mainly for Chemical plant. NFPA-70 article 500 defines the applicable rules which apply to electrical equipment and wiring in hazardous locations. E BECHTEL – ELECTRICAL ENGINEERING HANDBOOK COMPARISON OF IEC – ANSI/NEMA Page 16 of 44 HAZARDOUS AREA CLASSIFICATIONS IEC / US NFPA art. 500 CENELEC/NFPA 70 API 500 art. 05 (1) NFPA 497/NFPA 499 Flammable Vapour hazards Flammable Material Continuously Present Flammable Material Intermittently Present Flammable Material Abnormally Present Explosive dust continuously present Explosive atmosphere intermittently present Explosive dust atmosphere abnormally present Zone 0 Zone 1 Zone 2 Combustible Dust Hazards Zone 20 Zone 21 Zone 22 Class II Division 1 (2) Class I Division 1 (2) Class I Division 2 Class II Division 2 Table 4. 6A Notes 1 – NEC 505 specifies requirements for explosive gases and vapours only 2 – Not a direct comparison. Refer to definitions below. IEC 60079-10 Classification Definition : This standard classifies the areas within which there is or may be a flammable gas atmosphere. Zone 0 That part of a hazardous area in which a flammable atmosphere is continuously present for long periods. That part of a hazardous area in which a flammable atmosphere is likely to occur in normal operation.

That part of a hazardous area in which a flammable atmosphere is not likely to occur in normal operation and if it occurs, will exist only for a short period. Zone 1 Zone 2 IEC 61241-3 Classification Definition : This standard classifies the areas within which there is or may be a combustible dust atmosphere. Zone 20 A place in which an explosive atmosphere in the form of a cloud of combustible dust in air is present continuously, or for long periods or frequently. E BECHTEL – ELECTRICAL ENGINEERING HANDBOOK COMPARISON OF IEC – ANSI/NEMA Zone 21 Page 17 of 44 A place in which an explosive atmosphere in the form of a cloud of combustible dust in air is likely to occur in normal operation occasionally.

A place in which an explosive atmosphere in the form of a cloud of combustible dust in air is not likely to occur in normal operation but if it does occur, will persist for a short period only. Zone 22 NFPA 70 Classification Definition : Class I, Division 1 A location (1) in which ignitable concentrations of flammable gases or vapours can exist under normal operating conditions; or (2) in which ignitable concentrations of such gases or vapours may exist frequently because of repair or maintenance operations or because of leakage; or (3) in which breakdown or faulty operation of equipment or processes might release ignitable concentrations of flammable gases or vapours and might also cause simultaneous failure of electric equipment.

A location (1) in which volatile flammable liquids or flammable gases are handled, processed, or used, but in which the liquids, vapours or gases will normally be confined within closed containers or closed systems from which they can escape only in case of accidental rupture or breakdown of such containers or systems, or in case of abnormal operation of equipment: or (2) in which ignitable concentrations of gases or vapours are normally prevented by positive mechanical ventilation, and which might become hazardous through failure or abnormal operation of the ventilation equipment; or (3) that is adjacent to a Class I, Division 1 location , and to which ignitable concentrations of gases or vapours might occasionally be communicated unless such communication is prevented by adequate positive-pressure ventilation from a source of clean air, and effective safeguards against ventilation failure are provided. Class I, Division 2

Class II, Division 1 A location (1) in which combustible dust is in the air under normal operating conditions in quantities sufficient to produce explosive or ignitable mixtures; or (2) where mechanical failure or abnormal operation of machinery or equipment might cause such explosive or ignitable mixtures to E BECHTEL – ELECTRICAL ENGINEERING HANDBOOK COMPARISON OF IEC – ANSI/NEMA Page 18 of 44 be produced, and might also provide a source of ignition through simultaneous failure of electric equipment, operation of protection devices, or from other causes; or (3) in which combustible dusts of an electrically conductive nature may be present in hazardous quantities.

Class II, Division 2 A location where combustible dust is not normally in the air in quantities sufficient to produce explosive or ignitable mixtures, and dust accumulations are normally insufficient to interfere with the normal operation of electrical equipment or other apparatus, but combustible dust may be in suspension in the air as a result of infrequent malfunctioning of handling or processing equipment and where combustible dust accumulations on, in or in the vicinity of the electrical equipment may be sufficient to interfere with the safe dissipation of heat from electrical equipment or may be ignitable by abnormal operation or failure of electrical equipment. Class III Class III deals with fibres and are not normally encountered in the course of a P&C project. As such, they are not considered here. There is no classification under IEC standards with which to compare. 4. 6. 2.

Gas Grouping : Gas classification and ignition temperatures relate to mixtures of gas and air at ambient temperature and atmospheric pressure. A comparison of gas groupings per relevant code is given below. GROUPING OF TYPICAL GASES GAS Acetylene Hydrogen Ethylene Propane IEC / CENELEC NFPA 70 art. 505 NFPA 497 Group IIC Group IIC or Group IIB + H2 Group IIB Group IIA NFPA 70 art. 500 NFPA 497 Class I / Group A Class I / Group B Class I / Group C Class I / Group D Table 4. 6B 4. 6. 3. Dust Grouping E BECHTEL – ELECTRICAL ENGINEERING HANDBOOK COMPARISON OF IEC – ANSI/NEMA Page 19 of 44 Combustible dusts are also grouped by hazard category, IEC does not group combustible dusts. GROUPING OF TYPICAL DUSTS DUST Metal Dust Coal Dust Grain Dust

IEC / CENELEC NFPA 70 art. 505 NFPA 497 – NFPA 70 art. 500 NFPA 499 Group E Group F Group G Table 4. 6C 4. 6. 4. Temperature Classification A comparison of Temperature classification is given below EQUIVALENT TEMPERATURE CLASSIFICATIONS MAX. SURFACE TEMPERATURE deg C 450 300 280 260 230 215 200 180 165 160 135 120 100 85 IEC / CENELEC NFPA 70 art. 505 T1 T2 T3 T4 T5 T6 NFPA 70 art. 500 T1 T2 T2A T2B T2C T2D T3 T3A T3B T3C T4 T4A T5 T6 Table 4. 6D 4. 6. 5. Differences in Type of Certification There is a type of certification in use in the UK (and becoming increasingly common in Europe) called EEx ‘n’ or EEx ‘N’ as specified in IEC 60079-15 and is defined as “A ype of protection applied to electrical apparatus, such that, in normal operation, it is not capable of igniting a surrounding explosive E BECHTEL – ELECTRICAL ENGINEERING HANDBOOK COMPARISON OF IEC – ANSI/NEMA Page 20 of 44 gas atmosphere and a fault capable of causing ignition is not likely to occur”. Somewhat similar practices are allowed under the NFPA 70. Refer to articles 501-8, 502-8 (and also 503-6 for Class III areas). 4. 6. 6. Equipment Certification A comparison of the various methods of equipment certification and marking are given below. EQUIPMENT CERTIFICATION ‘Ex’ MARKING – IEC / CENELEC Example : Ex d II C T5 Ex De IIB T3 Explosion Protected Method of Protection Gas Group Temperature Class Table 4. 6E EQUIPMENT CERTIFICATION ‘Ex’ MARKING- USA NFPA art. 00 Example : Explosion Proof, Class I, Div 1, Groups A, B, C, D, T5 Explosion Proof Class I Div 1 Groups A, B, C, D T5 Method of Protection Permitted Class Permitted Division Gas Groups Temperature Class NFPA art. 505 Example : Class I, Zone 1, A Ex d II C T5 Class I Zone 1 A Ex d II C T5 Permitted Class Permitted Zone American National Standard Explosion Proof Method of Protection Group Gas Group Temperature Identification Number or Temperature Rating Table 4. 6F PERMITTED EQUIPMENT IN HAZARDOUS AREAS ZONE Zone 0/Class I Div 1 IEC / CENELEC Ex ‘ia’ NFPA 70 art. 500 Enclosures located in classified areas must be E BECHTEL – ELECTRICAL ENGINEERING HANDBOOK COMPARISON OF IEC – ANSI/NEMA Zone 1/Class I Div 1 Ex ‘d’, ‘ib’, ’p’, ‘e’, ‘s’(1), or ‘m’, and equipment suitable for Zone 0. Page 21 of 44 ertified to meet the requirements of NEC article 500-3 and API-RP500A : Class 1 – Explosion proof, intrinsically safe, purged or oil immersed to NEMA type 7 or 8. The electrical equipment to be installed in classified area must be certified by UL for the area classification. PERMITTED EQUIPMENT IN HAZARDOUS AREAS (Cont. ) ZONE Zone 2/Class I Div 2 IEC / CENELEC Ex ‘N’ or ‘n’ ‘o’, ‘q’, and equipment suitable for Zone 0 or Zone 1. IP6X enclosure with certificate of conformity for maximum surface temperature IP6X enclosure with certificate of conformity for maximum surface temperature IP5X enclosure with certificate of conformity for maximum surface temperature NFPA 70 art. 500 The electrical equipment to be installed in classified area must be certified by UL for the area classification. (i. e.

Class I Div2, Group C,D, T3) The electrical equipment to be installed in classified area must be certified by UL for the area classification. .(i. e. Class II Div2, Group E, T3) The electrical equipment to be installed in classified area must be certified by UL for the area classification. (i. e. Class II Div 1, Group E, T3) The electrical equipment to be installed in classified area must be certified by UL for the area classification. (i. e. Class II Div 1, Group E, T3) Zone 20/Class II Div 1 Zone 21/Class II Div 1 Zone 22//Class II Div 2 Table 4. 6H (1) Ex ‘s’ is not dealt with by IEC 60079 this is covered by BASEEFA SFA 3009. 4. 7 Substations Differing practices in the construction of substations are in place in Europe and the Americas.

Substation Construction Practice European/British Practice Substation is habitually a purpose constructed building. Equipment is delivered to site and installed / cabled when building complete. US/Americas Practice Substation often prefabricated at Vendor’s factory and shipped to site in one or more sections, with most internal cabling already in place. E BECHTEL – ELECTRICAL ENGINEERING HANDBOOK COMPARISON OF IEC – ANSI/NEMA • Package substations also available with switchgear/dry-type transformer housed within a purpose built enclosure (GRP or equivalent) Assembly of cast-resin transformer connected to LV switchboard/MCC is often termed “Package Substation”. Page 22 of 44

Outdoor equipment housed in an enclosure provided by the manufacturer as an integral part of the switchgear is widely used • Table 4. 7A 4. 8 Switchgear and MCCs 4. 8. 3 Switchgear There are a number of differing methods of construction and design for switchgear and MCCs within European and American practices. The main differences and comparisons are outlined in the table below. A more comprehensive comparison of differences can be found in [3, 5 and 6]. A number of significant differences are not specified in both sets of standards i. e. is specified in one, but not the other. SWITCHGEAR IEC/BS Generally more compact design with smaller footprint (space is a more precious commodity in parts of Europe and Asia). Minimum MV circuit breaker is 630A.

Access from rear generally not required (but can be provided by some British manufacturers) Equipment usually of the indoor type, therefore meaning that separate purpose built building is required to house it. CTs frequently have two or three secondary windings and are usually installed on the line side of the circuit breaker. CTs are usually of the wound type. ANSI/NEMA Dimensions of equipment generally not of major concern. Minimum MV circuit breaker rating is 1200A Access from rear generally provided. Outdoor equipment housed in an enclosure provided by the manufacturer as an integral part of the switchgear is widely used. ANSI switchgear allows for the installations of several sets of CTs (with single secondaries) on either side of the circuit breaker. CTs usually of the window (or doughnut type). SWITCHGEAR (cont’d) IEC/BS

Less compartmentalisation required Maximum design voltages vary IEC allows a lower BIL for a given service voltage – refer IEC 60298 (which refers to IEC 60071) Different requirements for short-circuit rating (see section 7. 4) ANSI/NEMA More stringent standards for compartmentalisation. Maximum design voltages vary Higher BIL Different requirements for short-circuit rating (see section 7. 4) E BECHTEL – ELECTRICAL ENGINEERING HANDBOOK COMPARISON OF IEC – ANSI/NEMA Switchboard thickness not specified by IEC, but is often specified separately by purchasing engineer. Arc resistant construction to IEC 60298 Appendix AA Circuit breaker current and breaking ratings (and busbar ratings) follow the R-10 series [3] in which each rated value is approx. 125% of the preceding value e. g. 630, 800, 1250, 1600A etc. Page 23 of 44

Minimum thickness of switchboard metal is specified by ANSI. Very few US installations with arc-resistant switchgear. Difficult with US design – refer to reference [3]. Circuit breaker current ratings are not so precise e. g. 1200, 2000, 3000 & 4000A. Breaking ratings are generally expressed in terms of MVA. Table 4. 8A 4. 8. 4 Motor Control Centres (MCCs) Comparison of MCC construction and design aspects as below. Note – many points in section 4. 8. 1 are also relevant here. MOTOR CONTROL CENTRES (MCCs) IEC MCC can be integrated with fused and circuit breaker feeders to form an MCC/switchboard Often formed by more than one incomer and bus section breaker(s).

Types of starters construction as follows • Fully withdrawable (disconnects both bus and cable) up to certain rating and fixed thereafter • Fixed • Swing out Construction can be • Front access (c/w with removable front panels for access to wireways for cable terminations) • Rear access • Back-to-back • Double fronted Usually fully fault rated – typically 50 kA rms for 1 second as upstream feeder device normally a circuit breaker. ANSI/ NEMA MCC separate from switchgear. Usually contains motor starters and feeders, but may be connected to the main switchgear via busbar transition sections Normally only one incomer and no bus section Starters normally withdrawable,( only on bus side) Construction usually either • Front access • Back-to-back

Low voltage swbd/MCCs are generally three phase and neutral and in these cases the neutral is usually grounded. Occasionally an I-T system is installed (no neutral). Usually fully fault rated – typically 65 kA rms for 5 cycles. Occasionally fed from low voltage switchboard by means of current limiting device. In these instances, the MCC does not have to be fully fault rated, only for the let through current of the feeder device. The neutral is not normally distributed throughout the low voltage system E BECHTEL – ELECTRICAL ENGINEERING HANDBOOK COMPARISON OF IEC – ANSI/NEMA Form of construction different. Normal practice for P&C business is probably Form 4 type 5 (minimum) segregation For single incomer to an MCC, the ollowing are often used as incomer devices • Air circuit breaker with or without integral overcurrent and earth fault protection • Isolating switch • Straight cable connection to busbars. Not specified. Not specified Page 24 of 44 Generally, cables are direct connected to busbars, but can be provided , in some cases, with main breaker NEMA codes specify three types of wiring – A, B & C. Table 4. 8B 4. 9 Earthing / Grounding Different practices are in place for earthing/grounding systems under both codes of practice. There is no significant difference between the materials utilised for NEC and International projects. Neutral Status: According to IEC 60364-3 the following neutral status are used in IEC applications. In P&C application the most common system employed is the TN-S.

TT system One point directly earthed at the supply transformer neutral, the exposed conductive parts of the installation being connected to earth electrodes electrically independent of the earth electrodes of the power system All live parts isolated from earth or one point connected to earth through an impedance, the exposed conductive parts of the electrical installation being earthed independently or collectively to the earthing system. One point directly earthed at the supply transformer neutral. The exposed conductive parts of the installation being connected to that point by protective conductor (PE). PE and N separate conductors PE and N combined in a single conductor throughout the system PE and N combined in a single conductor in a part of the system IT system TN system TN-S system TN-C system TN-C-S system: Table 4. 9A For the type of protections required for the above distribution systems refer to the IEC 60364-3 and to BS 7671. Earthing/Grounding IEC System neutral normally distributed in low voltage systems.

IT systems (no neutral) are installed, but tends to be in some parts of mainland Europe. ANSI/NEMA System neutral not normally distributed. E BECHTEL – ELECTRICAL ENGINEERING HANDBOOK COMPARISON OF IEC – ANSI/NEMA TNS is the typical system for P&C applications. IEC practice always uses a solidly earthed (grounded) neutral on low voltage systems such that downstream transformers are not required. The ground is at the neutral of the substation power transformer(s). As with cable sizes, earth conductor sizes are typically quoted in mm2. Earth conductors where specified as insulated shall be coloured Green and yellow Design of earthing systems in accordance with BS 7430 and Bechtel Standard 3DGE40E-001 Page 25 of 44

It is very common in applications that the MV system is low resistance grounded and the LV system is high resistance grounded ( in some cases the LV system can be solidly grounded) As with cable sizes, earth conductor sizes are typically quoted in terms of AWG. Grounding conductors where specified as insulated shall be coloured Green or Green and yellow. Design of earthing systems in accordance with IEEE 80 Table 4. 9B 4. 10 Cathodic Protection The basic principles of cathodic protection are the same although materials utilised are covered by the relevant national and international specification, codes and practices for electrical equipment and cable, refer to relevant sections for details. 5. BECHTEL STANDARD APPLICATIONS (BSAPS) 5. 1.

Electrical Load Database System (ELDS) There is no difference in the use of ELDS if it a US or international project other than the correct library data must be for US or European vendors, and different reports as set up by Houston or LORO offices can be selected. 5. 2. SetRoute There is essentially no major difference to SetRoute as to whether the project is International or US practices. The only minor difference is that NEC codes specify the capacity of a cable way (duct, tray etc) which is to be used, whereas on international projects, good design practice is applied. 5. 3. Electrical Transient Analysis Programme (ETAP) Essentially, it is irrelevant to ETAP whether a fault level or load flow study is carried out to IEC or ANSI standards.

The only fundamental differences in ETAP when comparing studies done to IEC or ANSI standards is that equipment (switching devices, fuses etc. ) parameters must be input to the correct standard. It is merely a case of choosing which standard the study is to be done to after that. E BECHTEL – ELECTRICAL ENGINEERING HANDBOOK COMPARISON OF IEC – ANSI/NEMA Page 26 of 44 5. 4. Power Tools (CAPTOR) There should be no difference in the principle of operation of Captor for the carrying out of protection setting studies. The only difference should be that for US projects the devices modelled will be based on US practices and IDMT curves will be based on ANSI or IAC standards.

IEC projects will model IEC devices with associated standard IEC IDMT curves (although some European devices allow the use of non-standard curves in addition to the standard ones) – refer to section 7. 14. Discrimination times between relays on IEC projects should be set as a minimum, in accordance with Bechtel standard 3DG-E31E-0001 (draft). 6. DESIGN PRACTICES 6. 1. Power Supply Layouts 6. 1. 1. Cabling Methods (P&C Projects) CABLING METHODS IEC Cabling installations to be as per Engineering Design Guide 3DG-E52E-001, Cabling Methods to be Used for Petrochemical Installations (International Projects). Cables shall normally be multi-core copper conductors with PVC or XLPE insulated steel wire armoured cables and PVC overall sheath (Cu/XLPE or PVC/SWA/PVC). Lead covered cable may be direct buried in areas of corrosively contaminated soil.

Single core cables may be utilised for larger size power feeders. In these cases, the wire armour shall be aluminium. Gland plates of the equipment should be non-ferrous. Underground cables are generally direct buried in both paved and unpaved areas, protected by a layer of concrete cable tiles. Pre-formed concrete trenches with covers may be specified for paved areas. Where there can be heavy vehicular traffic, e. g. u/g road crossings, cables are routed through PVC ducts encased in concrete with draw-pits at either end of the duct. Cables emerging from u/g or trenches to equipment or racks are protected by PVC ducts. Ducts may extend from equipment / cable racks to main trench.

Above ground cables are routed in ladder racks or trays. ANSI/NEMA/NFPA 70 Cabling installations to be as per NEC Article 300 and generally as follows. Cables shall normally be un-armoured TC (Tray Cable) Single core insulated type are utilised for lighting and small power circuits, and instrument circuits, from junction boxes (run in conduit). Underground cables are generally routed through PVC duct encased in concrete with rebars. Where there can be heavy vehicular traffic, e. g. u/g road crossings, ducts are encased in steel reinforced concrete. Cables emerging from u/g to equipment or racks are protected by rigid steel conduit. Above ground cables are routed in ladder rack type tray.

Trays are provided with covers. Cable runs from trays to equipment are pouted in threaded conduit systems. E BECHTEL – ELECTRICAL ENGINEERING HANDBOOK COMPARISON OF IEC – ANSI/NEMA Ladder rack is the preferred raceway type for major above ground cable routes. Tray is normally utilised for local instruments, lighting, and small power circuits such as on platform edges and skids. (Single cables may be directly fixed to steelwork). Cable entries to equipment are via purpose made glands providing an effective seal on the inner and outer cable sheath. Barrier type glands may be required for certain types of equipment in hazardous areas. Page 27 of 44

Cable ladder tray is the preferred raceway type for major above ground cable routes. Threaded conduit systems are normally utilised for local instrument run, lighting, small power circuits, and final cable routes to equipment. (Single cables for lighting and small power circuits are not installed in ladder type trays). Cable entries into equipment are via threaded conduit hubs. For vibrating equipment flexible conduit is used. Conduit seals may be required for certain types of equipment in hazardous areas, and conduit systems passing between classified and safe areas. Table 6. 1A CABLE TYPES USED ANSI/NEMA/NFPA 70 Un-armoured cables buried in conduit to provide protection.

Conduit may be PVC duct encased in concrete. Pull boxes are very commonly used. Un-armoured cable in overhead covered tray. Run in conduit off tray or where exposed. Conduit seal system is a requirement. IEC Armoured cable direct buried, in cable trenches (unpaved areas), in concrete cable trenches (paved areas), and in PVC sleeved concrete encased road crossings. Armoured cable in overhead cable tray and drop to the electrical users, clamping the cable to the structures or supporting by “open” conduit or EMT (no seals). Un-armoured cable only used for small power and lighting in buildings, generally in small bore conduit or PVC duct systems. Table 6. 1B 6. 2.

Lighting Layouts For international/IEC projects, preparation of lighting layouts should be done in accordance with LORO standard EL E45 901. For US/ANSI/NEC projects, they should be carried out in accordance with [Houston, please insert no. ]. 6. 3. Emergency Lighting The main differences between emergency lighting systems for both types of project are as follows. EMERGENCY LIGHTING IEC Emergency lighting systems in accordance with BS 5266 can either consist of standard light fittings with a central battery and/or backup generator or of self-contained emergency lighting fittings with integral battery packs. US STANDARDS NFPA 101 defines the requirements for emergency lighting. E

BECHTEL – ELECTRICAL ENGINEERING HANDBOOK COMPARISON OF IEC – ANSI/NEMA Systems with central UPS must be wired up with cables that “should either possess inherently high resistance to attack by fire or physical damage or be enclosed in suitable conduit, ducting, trunking in a channel so as to maintain the necessary fire protection and mechanical strength” The cables for emergency fittings with integral battery packs are not considered part of the Emergency Lighting System Page 28 of 44 Table 6. 3A 6. 4. Distribution Boards Construction of lighting and small power distribution boards under the two codes of practice are essentially the same. For field mounted distribution boards in hazardous areas, a long-standing IEC practice of installing individually certified MCBs into an enclosure (IP54 upwards) is becoming increasingly more popular for US projects. Previously, the prevalent method of design, was for standard industrial MCBs/fuses were installed in Ex’d’ boxes. 6. 5.

Terminations The fundamental difference in the way that cables are terminated in projects constructed to international or US practices is that the prevalent practice in international projects calls for the use of brass cable glands (Ex certified for use in hazardous areas), whereas the common practice in US plants is for the cable to be run to the terminal box in conduit. 6. 6. Materials Certification Type test certification of International electrical equipment is carried out at major type testing laboratories. For Europe the major ones are KEMA, ASTA, etc. whereas in the USA the major testing laboratories are UL and FM. 6. 7. Power and Control Cables A comparison of the different construction of power and control cables is given below. POWER AND CONTROL CABLES IEC Specification Format By number of conductors and their crosssectional area followed by an abbreviated

ANSI/NEMA/NFPA 70 By number of conductors and their AWG (American Wire Gauge) or MCM (100thCircular E BECHTEL – ELECTRICAL ENGINEERING HANDBOOK COMPARISON OF IEC – ANSI/NEMA description of the construction. Page 29 of 44 Mils, 1 mil = 0. 001’’) and cable type as designated by NEC. 4c 12 AWG MC type cable denotes – 4 core; 12 AWG cross-section; metal clad (armoured to NEC article 334). Further description may be required to specify cable make-up. TC – Tray Cable (non-armoured) NM – Non-metallic sleeved MC – Metal clad AC – Flexible metallic armoured cable MV – Medium Voltage PLTC – Power Limited Tray Cable 4c 2. 5mm2 Cu/XLPE/PVC/SWA/PVC denotes – 4 core; 2. mm2 cross-section; copper, cross linked polyethylene conductors with PVC inner sheath; steel wire armoured, and PVC outer sheath Examples General Descriptive Comparison : Non-armoured Armoured POWER AND CONTROL CABLES (Cont. ) IEC ANSI/NEMA/NFPA 70 Typical Cable Specified for International Projects Cu/PVC/SWA/PVC or XLPE/SWA/PVC depending on method of installation TC (tray cable) Depending on method of installation Grounded neutral – White or Natural Grey Equipment ground – Green or Green & Yellow Other core colours not specified under NEC, but typically Red, Blue and Black. Core Colours 2 core – Red & Black 3 core – Red, Yellow, & Blue 4 core – Red, Yellow, Blue & Black >4 core – White or Black with printed numbers Earth core – Green & Yellow stripes

For Codes, Standards and further details of cable types, configurations, and core size comparisons, see APPENDIX B Table 6. 7A 6. 8. Instrumentation and Communication Cable Instrumentation and communication cable physical characteristics are generally consistent with Table 6. 7A above. 6. 9. Cable Glands and Terminations In international practice, the prevalent method of terminating cables in P&C applications is with the use of threaded brass cable glands (Ex certified for use in hazardous areas. Prevalent US practice is for the conduit to be sealed at the terminal box. A further comparison of the two systems is given below. CABLE GLANDS & TERMINATIONS IEC Cable Entries into Equipment

IP rated Threaded Brass Cable Glands (Ex Certified for classified / hazardous areas) ANSI/NEMA/NFPA 70 Where conduit systems are not utilised, via a cable connector, and MC cable E BECHTEL – ELECTRICAL ENGINEERING HANDBOOK COMPARISON OF IEC – ANSI/NEMA Page 30 of 44 Proprietary cable terminators similar to IEC type. Cable glands are available. Standard Sizes Entries specified as ISO metric in standard Sizes 20, 25, 32, 40, 50, 63 and 75 mm. NPT and PG threaded also available. Pitch size of the thread is generally 1. 5mm. Entries are NPT in standard conduit sizes ? ’’, ? ’’, 1’’, 1? ’’, 1? ’’, 2’’, 2? ’’, 3’’, 3? ’’, 4’’, 5’’ & 6’’. Table 6. 9A 6. 10.

Cable Tray / Ladder rack The preferred method of cable support under international practice is with cable ladder and/or tray. Not normally used under US practice. CABLE TRAY AND LADDER RACK IEC Definition Ladder Rack Cable Tray Ladder Cable Tray Cable Tray (6″ and bigger) Channel : one piece tray, solid or ventilated, ( ( 4″ and smaller) Ladder Cable Tray Designed, constructed, tested and installed in accordance with NEC article 318 & NEMA VE 1 & 2 METAL CABLE TRAY SYSTEMS or NEMA FG 1 FIBREGLASS CABLE TRAY SYSTEMS ANSI/NEMA/NFPA 70 Description Ladder Rack Designed, constructed, tested and installed in accordance with BS6946 & IEE Wiring Regulations (BS7671) For installation refer to IEE Wiring Regulations. BS7671

Typical rung spacing 300mm; other spacings are available as standard Standard length 3m or 6m Standard widths 150, 300, 450, 600, 750 and 900mm Materials typically hot dipped galvanised steel, aluminium, or GRP Classified as, Medium, Heavy, and Extra Heavy Duty Tray Designed, constructed, tested, and installed in accordance with BS6946, Specification for Metal Channel Cable Support Systems, BS7671 Requirements for Electrical Installations, and IEE Wiring Regulations. For Installation refer to NEMA VE 2 For permissible cable types to be installed in cable trays refer to NFPA 70 article 318-3 For cable tray allowable fill refer to NEC article 318-9 & 10 Typical rung spacing is 9’’ Standard length 12ft or 24ft Standard widths 6’’, 12’’, 18’’, 14’’, 30’’, and 36’’ Materials typically hot dipped galvanised steel, aluminium, fibreglass Classification is in accordance to NEMA VE 1 Channel or Trough

Designed, constructed, tested, and installed in accordance with NEC article 318 and NEMA VE 1 Metal Cable Systems or NEMA FG 1 Fibreglass Cable Tray Systems. Installation Guidance NEMA VE 2. For permissible cable types to be installed in trays NEC article 318-3. E BECHTEL – ELECTRICAL ENGINEERING HANDBOOK COMPARISON OF IEC – ANSI/NEMA Page 31 of 44 Standard Length 3m Standard Widths 50, 75, 100, 150, 300, 450, 600, 750, and 900mm Material typically hot dipped galvanised steel or GRP. Classified as, Medium, Heavy, and Extra Heavy Duty Tray fill requirements NFPA 70 article 318-9 & 10. Standard length 9’ Standard Widths 2’’, 3’’, 4’’, and 6’’ Material typically hot dipped galvanised steel , aluminium, or GRP.

Table 6. 10A 6. 11. Ducts and Conduit CONDUIT IEC Not normally used. Sometimes specified for lighting and small power circuits buildings, and cabling on package equipment. Steel Conduit : Manufactured and tested in accordance with BS EN50086, BS 31 : 1940 and BS4568 (ISO threads) Classified as Extra Light, Light, Medium, Heavy, and Extra Heavy Gauge. For outdoor use, Threaded Heavy or Extra Heavy is normally specified. Standard sizes 16, 20, 25, 32, 40, and 50mm. ANSI/ NEMA/NFPA 70 Commonly used for lighting, small power and instrument circuits, and for final run to equipment from cable trays. Rigid Metal Conduit, ‘RMC’ (Heavy Duty) to ANSI C80. and NEC article 346 : Manufactured from steel or aluminium, of std. Wt. Pipe of nom. Bore ? ’’ thro’ 6’’. For corrosive atmos. May be specified hot dipped galv’d or PVC coated. RMC is suitable for installation underground, direct buried or encased in concrete. RMC installations must comply with NEC article 300, Threaded Rigid Metal Conduit, and may be installed in hazardous (classified) areas Class 1 Division 1 & 2, provided the installation meets the requirements of NEC article 501-4. Intermediate Metallic Conduit ‘IMC’ (Medium Duty) to ANSI C80. 6 and NEC article 345 : As per RMC except has reduced wall thickness and specified up to 4’’ n. b. only. Electrical Metallic Tubing ‘EMT’ (Light Duty) to ANSI C80. and NEC article 348 : As per IMC except of reduced wall thickness and specified up to 4’’ n. b. only. EMT is not permitted for installation in Class 1 Division 1 areas or where exposed to severe mechanical damage. Conduit connections to fittings and equipment are NPT Conduit connections are usually iso Metric Table 6. 11A E BECHTEL – ELECTRICAL ENGINEERING HANDBOOK COMPARISON OF IEC – ANSI/NEMA Page 32 of 44 PVC DUCTS IEC PVC ducts are generally only used for cable “stub-up” sleeves, encased in concrete at road crossings ANSI/ NEMA/NFPA 70 PVC ducts are used for underground installations, either direct buried (under paving) or encased in concrete (unpaved areas, and areas of heavy vehicular traffic). Table 6. 11B 6. 12.

Motor Control Stations and Switches Control stations, pushbuttons, and switches have similar functional properties, however there are differences in enclosure types, and entry details. MOTOR CONTROL STATIONS AND SWITCHES IEC ANSI/ NEMA/NFPA 70 Ingress protection IP rating in accordance with IEC 60529 Typically IP65 is specified for outdoor use. Cable entries are normally threaded metric. However, NPT and PG threads are also available. Ingress protection normally specified as a NEMA type, UL approved Cable entries are normally via threaded conduit hubs. Table 6. 12A 6. 13. Junction and Terminal Boxes Junction and terminal boxes have similar functional properties, however there are differences in enclosure types, and entry details.

JUNCTION BOXES AND TERMINAL BOXES IEC Definition : Junction Box Terminal Box Junction Box Outlet Box (conduit installations) Pull Box (conduit installations) Splice Box (conduit installations) ANSI/ NEMA/NFPA 70 Description : Ingress protection IP rating in accordance with IEC 529 Typically IP65 is specified for outdoor use. Cable entries are normally threaded metric. However, NPT and PG threads are also available. Ingress protection normally specified as a NEMA type Cable entries are normally via threaded conduit hubs. Table 6. 13A E BECHTEL – ELECTRICAL ENGINEERING HANDBOOK COMPARISON OF IEC – ANSI/NE