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- Type of Protective Device Correction Factor Semi-enclosed fuse to BS 3036 0.725 Others 1.0 5. Correction factors for cables installed in enclosed trenches Table 6: Correction factors for cable installed in enclosed trenches (Installation Methods 18, 19 and 20 for Appendix 3) The correction factors tabulated below relate to the disposition of.
- For more than three current-carrying conductors in a raceway or cable, multiply the allowable ampacities shown in the Maximum Allowable Ampacities table by the percentages shown below. Number of Conductors Correction Factors for Allowable Ampacities of Conductor
- Without correction factors, a cable in service can lead to serious failure. Ambient Temperature Ampacity tables in the National Electrical Code list ampacity values that are based on an ambient temperature. Should the temperature of the application differ from the referenced ambient temperature, a correction factor is applied to adjust the.
- A table of correction factors for ambient temperature may be viewed in BS7671. The symbol for the Correction factor for ambient temperature is Ca . Thermal Insulation - If a cable, through any part of its run, passes completely through thermal insulation this can greatly impede its ability to dissipate heat generated through current flow

Email PDF. Table 310.15(B)(2)(b) Ambient Temperature Correction Factors Based on 40°C (104°F) For ambient temperatures other than 40°C (104°F), multiply the allowable ampacities specified in the ampacity tables by the appropriate correction factor shown below ** TABLE 6 - 2 Correction Factors for Various Ambient Earth temperatures 21 TABLE 6 - 3 Group Correction Factors - Cables in Air 21 TABLE 6 - 4 Group Correction Factors - Conduits in Air 21 TABLE 6 - 5 Single Conductor Cable Underground Ducts - One Circuit**, Three Cables in Separate Ducts 2 the adjustments shown in Table 310.15(B)(3)(c) shall be added to the outdoor temperature to determine the applicable ambient temperature for application of the correction factors in Table 310.15(B)(2)(a) or Table 310.15(B)(2)(b) Where conductors or cables are installed in circular raceways exposed to direct sunlight on or above rooftops

* Cable Spacing C (in): EPR 3 Correction Factor Installation Type Table-4: 5 100 0*.09 PVC 5 Inductance (mH): 5 133 0.09 Reactance (ohms): 8 100 0.115 Correction Factor for Installation Table-4 Resistance Calculation 8 133 0.14 AC Resistance @ 20C: /1000': 15 100 0.175 Air RE: Cable Correction factor Application 7anoter4 (Electrical) 12 Apr 21 15:58 I have still a problem .According to IEC 60287-2-1 Table 1 - Thermal resistivities of materials the concrete resistivity is 1[100] and that increases very much the thermal resistance T4 -from duct through concrete duct bank to the native surrounding earth

RE: Correction factor for cable sizing 7anoter4 (Electrical) 8 Nov 18 06:35 Calculated for single core 240 mm^2 copper conductor 0.6/1 kV xlpe insulated is 192.8A for 18 cables [ 351 A for one circuit as per IEC 60364-5-52 Table A.52-5] The grouping correction factor. Appendix 4 Table 4C1, 4C4 or 4C5 (in free air) or Table 4C2 or 4C3 ( buried or in ducts ) Cc The protective device correction factor. Appendix 4 Section 4 gives 0.725 for BS3036 'rewireable' fuses. Ci The correction factor for cables embedded in thermal insulation Regulation 523.7 - Table 52.2 Length in. Find nearest lower voltage drop value in tables, in correct column for type of conductor, conduit and power factor. Read conductor size for that value. Where this results in an oversized cable, verify cable lug sizes for molded case circuit breakers and fusible 4 switches. Where lug size available is exceeded, go to next higher rating

- Method of Calculating the Correction Factors for Cable Dimensioning in Smart Grids View the table of contents for this issue, or go to the journal homepage for more 2017 IOP Conf. Ser.: Mater
- Correction factors are obtained from the following tables (dependant upon cable type and installation): Table 4B1 - rating factors for cables in air, ambient other than 30 °C ; Table 4B2 - rating factors for buried cables, ambient other than 20 °C ; Table 4B3 - rating factors for buried cables, thermal resistivities other an 2.5 K.m.W-
- b) Added a clause to cover communication cable c) Expanded and updated the clause for fiber-optic cable d) Arranged the annexes to better follow the flow of control cable systems selection and design e) Expanded and updated the annex for cable selection to include a table of common cable size
- According to above detail correction factors: - Ground temperature correction factor (K2) = 0.89 - Soil correction factor (K4) = 1.05 - Cable depth correction factor (K5) = 1.0 - Cable distance correction factor (K6) = 1.0. Total derating factor = k1 · k2 · k3 · K4 · K5 · K6 · K7 - Total derating factor = 0.9
- where T is the total pulling tension (lb), L is the length (ft) of cable feeder you're pulling, w is the total weight (lb/ft) of the conductors, f is the coefficient of friction (usually 0.5 for well-lubricated conditions), and W is the weight correction factor

Table 12-6: Correction factors Grouping on the wall, floor, ceiling in conduits or closed wire ways (in accordance to DIN VDE 0298-4, 2003-08, Table 21). = Symbol of one single core or one multicore cable ** temperature correction factor can be looked up from a table, for a given standard temperature (15 ºC, as determined by CSA and UL)**. 1.2.1. Calculation The insulation resistance can be calculated using the following formula: T T K Measured S dard e S dard Measured R R tan ln tan Where: R. Measure carrying capacity for a cable. Table 4C1 of BS7671 gives values for cables that are grouped and touching. The symbol for correction factor for cable grouping is Cg. Protective Device - Where the circuit protective device is a semi-enclosed fuse to BS3036 a correction factor must be applied to make up for potential hazards that may otherwise. C g is correction factor for grouping (Table 4C of BS 7671: 2008) From Table 4C1 for a group of 7 cables single layer multicore on a perforated cable tray, C g = 0.73. C i is correction factor for conductors surrounded by thermal insulation. The cables are not surrounded by insulation so C i =

Tables 12B, 12C and 12D provide correction factors for Table 12A based on temperature, insulation and layering. Table 12E, referenced by Rules 4-006 and 12-406 and Tables 5D, 12B and 12C, provides a lookup of allowable ampacities for Type DLO cables, in a permanent installation, in cable-tray Correction factors are applied to situations which inhibit a cable from dissipating its heat caused by the normal flow of current through it. Therefore, the following correction factors, if applicable, are applied: Ambient temperature, C a This factor is obtained from Table 4C1 (or Table 4C2 if a rewireable fuse to BS 3036 is used) in Appendix. The title to Table 4B1 (in my slightly out of date blue-cover regs) says 'Correction factors for groups of more than one circuit of single-core cables, or more than one multicore cable' and the subheading in the table itself reads Number of circuits or multicore cables, so perhaps the oft-quoted count circuits, not cables isn't entirely. ** Correction Factors For Alternative Ambient Temperatures Ambient Temperature 25°C 30°C 35°C 40°C 45°C 50°C 55°C 60°C Correction Factor 1**.03 1.0 0.94 0.87 0.79 0.71 0.61 0.50 For Grouping Refer to Table 4C1 of BS 7671 E. & O.E. Conductor C.S.A. Current carrying capacity Voltage drop single phase a.c. Maximum mass supportable by twin.

- (mV/A/m) is voltage drop factor of particular cable under use. BS 7671 however, provides further accuracy in the calculations and suggests to apply temperature correction and power factor correction to conventional voltage drop factor (mV/A/m), so that voltage drop is calculated for actual corrected current flowing in the circuit
- Low voltage cable derating factors -Australian and New Zealand conditions The current rating of a cable is affected by the presence of certain external influences. Under such conditions the current ratings given from the standard AS/NZS 3008.1 shall be corrected by the application of an appropriate factor or factors. Wher
- Table 310.15(B)(2)(A) Ambient Temperature Correction Factors Based on 30°C (86°F) is one of the tables where adjustment factors can be found. For example, a 10 AWG 3C 600 V cable is installed in an ambient temperature of 50°C. According to NEC 2014 310.15(B)(2)(A), the cable's ampacity would need to be multiplied by a correction factor
- IEC 60502 is an International Electrotechnical Commission standard, which gives current ratings for medium voltage cables. The calculation of cable rating follow t he derating factor method, see Cable Derating (Factors).. The IEC 60502 standard is in two parts; part 1 for voltages up to 1 kV and part 2 for voltages from 1 kV to 30 kV
- Correction factors depend on the type of insulation. To facilitate and simplify corrections average some correction factors, for different insulation materials, have been developed over the years. Table 1 is an example of commonly used temperature correction factors for typical insulation systems used in rotating equipment and cables
- A correction factor is a multiplier that is calculated and used to adjust the amount of energy pushed through a cable based on the amount of heat that is radiated when the cable is conducting energy. The National Electrical Code table for Ambient Temperature Correction Factors can provide the appropriate correction factor based on your cable's.

Corrected Ampacity = Table 310.16 Ampacity × Ambient Temperature Correction Factor. For a dry location, use the 90°C column for THHN. Ambient Temperature Correction Factor for 100°F = 0.91 for THHN. Table 310.16 ampacity for 10 THHN is 40A at 90°C in a dry location. 10 THHN = 40A × 0.91 = 36.40A. This is too small for the 40A load Table 310.15(B)(2)(a) Temperature Correction Factors. For ambient temperatures other than 30°C (86°F), multiply the allowable ampacities shown above by the appropriate factor shown per the table below Table 310.15(B)(2)(b) Ambient Temperature Correction Factors Based on 40°C (104°F) is now Table 310.15(B)(2). Table 310.15(B)(3)(a) Adjustment Factors for More Than Three Current-Carrying Conductors is now Table 310.15(C)(1). The above code sections and tables are pretty much the same other than a few minor changes to provide clarity and.

* Based on NEC Table 310*.15(B)(2)(a)[Formerly Table 310(16)] - Ambient Temperature Correction Factors Based on 30°C (86°F) Adjustment Factors - See NEC Table 310.15 (B)(3)(a) Where the number of current-carrying conductors in a raceway or cable exceeds three, the allowable ampacities shall be reduced as shown in the following table The DC resistance of copper wire increases with increasing temperature in accordance with the formula: On the basis of the above formula, we now generate a table of correction factors for copper conductors in operating in the temperature range 25 - 200 degree celsius

- The issue of ambient temperature and correction factor adders for raceways and cable assemblies installed above rooftops has been seriously debated by code panel 6 for several cycles. In the 2017 NEC, a code change proposal from a special task group was accepted to delete the table
- WIRE / CABLE TYPE: Insulated wire types like THHN/THWN-2, XHHW-2 and USE-2/RHH/RHW-2 have an insulation temperature rating of 90℃, and any temperature correction factors or ampacity adjustment factors can be applied to the insulation temperature rating
- For ambient temperatures other than 30°C (86°F), multiply the allowable ampacities specified in Table E3705.1 by the appropriate correction factor shown in Table E3705.2. [310.15(B)(2)] TABLE E3705.2 [Table 310.15(B)(2)(a)] AMBIENT TEMPERATURE CORRECTION FACTORS

** TEMPERATURE CONVERSION TABLE Celsius----The numbers in heavy type refer to the temperature either in degrees Celsius or Farenheit which is desired to convert into the other scale**. The figures have been calculated by using the following formulae:- C° = 5/9 x (F°- 32) F° = (9/5 x C° + 32) RESISTANCE TEMPERATURE CORRECTION FACTORS This factor depends on the cable time constant and also on the cable diameter. For more details, see IEC 60092-352. 6-1-4 U.V. solar radiation We recommend shielding cables from direct solar exposition, but in case of solar radiation, a correction factors must be applied to the current carrying capacities given in the table

Table B.52.15 Correction factors for ambient ground temperatures other than 20 °C to be applied to the current-carrying capacities for cables in ducts in the ground Table B.52.17 Reduction factors for one circuit or one multi-core cable or for a group of more than one circuit Note: NM cable shall have a 90 degree C insulation (used for derating) but shall be used at the 60 degree C ampacity (334.80). Circuit is Type AC or MC cable that complies with Note 1. If circuit is 15, 20, 30 40, or 50 amperes branch-circuit supplying two or more outlets or receptacles See Table 210.24 Since the ambient temperature in this example is 30°C and Table 310.15(B)(16) is based on 30°C, applying an ambient temperature correction factor also is not necessary. Because there are no correction or adjustment factors, look in Table 310.15(B)(16), in the 75°C column, for the allowable ampacity of this conductor * This calculator also provides wire size correction factors for temperature, number of conductors in a raceway, and voltage drop for long wire runs*. This calculator is based on NEC (NFPA 70®: National Electrical Code® (NEC®), 2014 Edition) Table 310.15(B)(16-17). Advanced Wire Ampacity Calculato

No ampacity adjustment factor correction is required for three conductor cables paralleled in cable tray. See 2005 NEC Section 392.11(A)(1) Size of the conductors required is 350 kcmil [610 amperes/2 conductors per phase (two - three conductor cables required) = 305 amperes - a 350 kcmil THHN/THWN insulated copper conductor's maximum ampacity rating is 310 amperes Table 1: The different cable parameters used and thier calculation as the correction factor (or the It can be seen that the cable derating factor is independent of the type cables filled.

To size conductors per NEC Tables, hand calcs X X 60 and 90 Circuit breaker and fuse sizing To size circuit breakers and fuses per NEC Tables, hand calcs X X 60 and 90 Conduit Fill/Tray Size To size conduit and cable tray per NEC NEC Tables, Cablematic Plus X X 60 and 90 Voltage drop For heavily loaded and/o Correction Factor: 1.0: 0.96: 0.91: 0.86: 0.81: 0.76: 0.70: 0.64: 0.57: 0.50: Ambient Temperature: 140°C: 145°C: Correction Factor: 0.40: 0.28: Notes: The current ratings tabulated are for cables in free air but may also be used for cables resting on a surface. If the cable is to be wound on a drum on load the ratings should be reduced in. The correction factors in Table 310.15(B)(1) are percentages, and they are applied to the normal ampacity values provided in Table 310.16 to reduce their value. For example, a THWN No. 6 copper conductor from Table 310.16 is stated to be worth 65 amps. But according to Table 310.15(B)(1), when that same conductor is installed in an ambient. Rating factors for other number of cores Cable Categories: YSLY, YSLCY, FLEXI UL 1007 / 1015 SC Number of current carrying 5 2.5 1.5 1.0 0.75 0.5 4 185 42 448 240 528 300 608 in free air 7 10 14 19 24 40 61 Rating factors for cables Rating factors for cables in earth (burial) 0.75 0.65 0.55 0.50 0.45 0.40 0.35 0.30 0.70 0.60 0.50 0.45 0.40 0.35.

4 table 2 (see rules 4-004. 8-104, 12-012, 12-2212, 26-000; 26-744, 42-008, 42-016, and tables 5a, 5c, 19 and d3) allowable ampacities for not more than 3 copper conductors in raceway or cable c) From cable reel to cable tray, the cable is fed from the top of the reel to main-tain required curvature. Sheaves, or a shoe, may be used to guide the cable into the tray. Figure F-3 Cable Feed into Cable Tray d) Cable sheaves or a shoe may be used to guide cable into the desired direction, maintain minimum bend radius, and reduce friction The ampacity Tables in the Code are migrating to raw (calculated) ampacities, which may be limited by various Rules and correction factors in the Code. Tables 1 to 4 have been partially recalculated to reflect this shift. In order to align the existing underground Tables (D8A to D15B) with the rest of the Code, th Temperature Correction Factor, K 1 when cable is in the Air = 0.88 (for 50* Amb temp & XLPE cable) Cable Grouping Factor (No of Tray Factor), K 2 = 0.68 (for 3 trays having 9 cable each) Total derating factor = K 1 x K 2 = 0.88 x 0.68 = 0.598 correction factors are simply applied as divisors to the design current (load current) of the circuit (I b) to ensure the correct current carrying capacity of the cable is determined for the installed conditions. Cable grouping (C g) Appendix 4 contains group rating factors contained in tables 4C1 to 4C6. the 17th edition, published in 2008

Table 310.15(B)(2)(a) Adjustment Factors for More Than Three Current-Carrying Conductors in a Raceway or Cable Number of Current-Carrying Conductors Percent of Values in Tables 310.16 through 310.19 as Adjusted for Ambient Temperature if Necessary 4-6 80 7-9 70 10-20 50 21-30 45 31-40 40 41 and above 3 This paper presents a study of the factors that determine cable ampacity adjustments and corrections in the electrical distribution network. Ampacity is defined as the maximum current carrying. - Short Circuit tables. - Temperature correction factor in air . - Ground temperature correction factor . - Soil Correction factor . - Thermal correction factor . - Cable distance correction factor . - Cable depth correction factor. - Cable grouping factor. - Cables construction. - Voltage drop for single core LV cables (Copper)

Ampacity changes due to ambient temperature are called correction factors. Standard air temperature is between 78 o F and 86 o F according to the 2017 NEC. When ambient temperature is below 78 o F or higher than 86 o F, then the conductor ampacity must be corrected based on the percentages listed in Table 310.15(B)(2)(a) You always multiply by the value given in table 310.15(B)(2)(b) for ambient temperature correction. For example: 2 AWG copper XHHW has an ampacity of 115. You are going to use it in an ambient temperature of 115 degrees F. 115 X .85 (the value in the table) = 97.75 amperes Choose either the 86°F table [Table 310.5(b)(2)(a)] or the 104°F table [Table 310.5(b)(2)(b)] to find your temperature correction factor. Then, you can either multiply the table ampacity by the correction factor or divide your calculated amps by the correction factor prior to looking up the ampacity FPN No. 1: See Annex B, Table B.3.10.1.11, for adjustment factors for more than three current-carrying conductors in a raceway or cable with load diversity. FPN No. 2: See 3.66.2.14(a) for correction factors for conductors in sheet metal auxiliary gutters and 3.76.2.13 for correction factors for conductors in metal wireways For the application of the formula it is necessary to know the exact cable specification. For a fast calculation of the section it is recommended to use the following tables which give the value of the voltage drop, available for most of the low voltage cables and for different values of cos ϕ

* If we bundle nine current-carrying 12 THHN conductors in the same raceway or cable, the ampacity for each conductor (30A at 90°*C, Table 310*.16) needs to be adjusted by a 70 percent adjustment factor [Table 310.15(B)(2)(a)]. Adjusted Conductor Ampacity = 30A x 0.7 Selection Table T33 N T33: Correction Factors Ambient Temperature ( C ) Conductor Temperature o 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 1.35 Correction Factor Arrangement of Cables Number of Circuits Bunched in air Bunched on a surface or enclosed Single layer on wall or floor Single layer on wall Touching Spaced Touching Spaced 2 The nearest size of standard trunking with a capacity factor greater than 1239.6 is 75 x 50mm? (No. of Cables) 10 x 95 (Factor for 35mm² cable) = 950 (No. of Cables) 16 x 18.0 (Factor for 4mm² cable) = 289.6 Total Cable Factor = 1239.6. Standard Trunking Cable Factors The correction factor in Table G.1 is to be applied to obtain the free-space antenna factor for a biconical antenna in the frequency range 30 MHz to 200 MHz. This correction only applies to biconical antennas that do meet the aforementioned criteria related to size and balun impedance

Thermoplastic is good upto 70C. 70-20 = 50C. 0.004x50 = 0.2. So the correction factor is 1.2. If you apply the factor of 1.2 to table I1 in the OSG or B1 in GN3, you will get the voltage drop numbers in BS 7671 Say the cable has a normal rating of 10A, then with a rating factor of 0.65 this would come down to 6.5A It can also be used in reverse - if the cable needs to carry a certain current then dividing that current by the rating factor will give the normal cable capacity that is needed for this installation Where the horizontal clearance between adjacent cables exceeds 2De, no correction factor need be applied. 2. Not applicable to Mineral Insulated Cables. Please refer to Table 4B2 of S7671 for the required correction factors. 3. For details, please refer to BS7671:2001 Table 4B1 <Back> (DIN VDE 0298-4 Table 20, installation method D) is used in SIMARIS design for both reference installation methods D1 and D2. IEC 60364-5-52 specifies separate correction fac-tors for cable burying directly in the soil (see IEC 60364-5-52 Table B.52.16). However, these correction factors - a

Adjustment factors for more than three current-carrying conductors in a raceway or cable. the number of current-carrying conductors in a raceway or cable exceeds 3, the allowable Where Table Temperature Correction Factors For ambient temperatures other than 300C (860F), multiply the allowable ampacities shown abov For a cable having thermoplastic insulation with a maximum permitted temperature of 70°C, this adjustment can be made by simply multiplying the maximum Z s values in the appropriate table by 0.8 (Appendix A2 of GN 3). From Table B8 of the OSG, the correction factor is 1.06

Temperature Correction Factors The determination of temperature correction factors using DFR method is based on the fact that a power factor measurement at a certain temperature and frequency corresponds to a measurement made at different temperature and frequency. With DFR technique, individual temperature correction factors ca The NEC requires a 'weather **correction** **factor'** to determine the highest possible voltage. Solar panels produce less power the hotter they get; they produce more power the colder they get. The NEC has a **table** (**Table** 690.7, Voltage **Correction** **Factors** for Crystalline and Multicrystalline Silicon Modules) that gives the **correction** **factor**, based on. The appropriate table of current-carrying capacity, in Appendix 4 of BS 7671, and the appropriate column within that table are achieve overload protection for a buried cable circuit the 1.45 factor given in Regulation 433.1.1 Table 1.1 Selection of current and of correction factors Overcurrent protective device Protection provided For I. Single-conductor Cable •USE-2 •PV wire •In raceway only when > 30 volts and readily accessible, 690.31(A) Art. 690.31(E) •Multiply by correction factor in Table 690.7 •Or use manufacturer's correction factors •St. Paul average mean low temperature is approximately 4 deg. F = 1.18 (-16 deg. C). Solis Seminar Episode 19: How to Section AC Cable for Solar PV system

Table 4.23 Power Cable Current Carrying Capacity 104 Table 4.24 Utilization of Correction Factor for Power Cable Size 4.0mm2 105 Table 4.25 Utilization of Correction Factor for Power Cable Size 6.0mm2. 106 Table 4.26 Utilization of Correction Factor for Power Cable Size 10.0mm2 10 Correction factor k1. Reduction factor k2. Table B.22. Table B.23 . Cables buried in the ground. Reduction factors for group of more than one multi-core cable to be applied to reference current-carrying capacities for multi-core cables in free air; Table B.22 - Reduction factors for groups of more than one multi-core cable in air - To. Table 310.15(B)(2)(a) Ambient Temperature Correction Factors: Ambient Temperature Correction Factors Based on 30°C (86°F) Table 310.15(B)(3)(a) CCC Count Adjustment Factors: Adjustment Factors for More Than Three Current-Carrying Conductors in a Raceway or Cable: Table 310.15(B)(16) Conductor Ampacitie

Table 310.15(B)(2)(a) Adjustment Factors for More Than Three Current-Carrying Conductors in a Raceway or Cable Number of Current-Carrying Conductors Percent of Values inTables 310.16 through310.19 as Adjusted for Ambient Temperature if Necessary 4-6 80 7-9 70 10-20 50 21-30 45 31-40 40 41 and above 35 (b) More Than One Conduit, Tube. Table B.52.14 - Correction factor for ambient air temperatures other than 30 °C to be applied to the current-carrying capacities for cables in the air.....53 Table B.52.15 - Correction factors for ambient ground temperatures other than 20 ° CORRECTION FACTORS FOR VARIOUS AIR TEMPERATURES 30 1.00 1.00 1.00 1.00 1.00 1.00 1.00 While current ratings for power cables have been officially assigned by such groups as the Insulated Cable Engineers Association and the National Electric Code, no such ratings have been officially This table should only be used as a starting point. Correction-factors at ambient temperature over 30°C For temperatures over 30°C, multiply the current-carrying capacity in the tables times correction-factor (f) to obtain the allowable current. Ambient Temperature ° cable designers guide table of contents cable geometry page 7-1 how to specify cable pages 7-2, 7-3 basic introductory information pages 7-4, 7-5 glossary of abbreviations and terms pages 7-6, 7-7, 7-8 wire awg page 7-9 synopsis of wire & cable pages 7-10, 7-11 mil-std-681 color coding page 7-1

CABLE FACTORS Nominal Conductor size mm²1.5 solid 1.5 stranded 2.5 solid 2.5 stranded 4 6 10 16 25 35 50 70 95 Factor copper or aluminium 8.6 9.6 11.9 13.9 18.1 22.9 36.3 50.3 75.4 95 133 177 227 STANDARD TRUNKING CAPACITY FACTORS Trunk Size Capacity Factor Trunk Size2 Capacity Factor3 50mm x 50mm 1037 150mm x. Zs is the loop impedance given by Tables 41B1, 41B2 or 41D of B S 7671 F is the conductor temperature resistance factor from Table 1C or Table 1D in Appendix 1 of GN3. An example of how this formula may be used is given above right: Calculating temperature-adjusted maximum Z s values Following calls to the NAPIT Helpline on the subject, Bill Allan

or cable exceeds three, or where single conductors or multi conductor cables are stacked or bundled longer than 24 inches without maintaining spacing and are not installed in raceways, the allowable ampacity of each conductor shall be reduced as shown in the following table According to the ambient correction factors at the bottom of Table 310-16, an adjustment must be made of 0.88 for 75°C and 0.91 for 90°C. Calculate, using a 75°C conductor such as THWN: 300 kcmil copper has a 75°C ampacity of 285A. Using the factors noted earlier: 285A x 0.80 x 0.88 = 201 correction factor k and the temperature coefficient α are given in the graphs below. MULTI-METAL CONDUCTORS In overhead lines (OHL), often utilized for long haul electricity distribution, aluminium tends to get preference for economic reasons. Because of its ductility, the cable is equipped with a cor