267

Ap

pend

ices

Table 4C5 Rating factors for groups of one or more circuits of single-core cables to be applied to reference current-carrying capacity for one circuit of single-core cables in free air – Reference Method F in Tables 4D1A to 4J4A.

Samples from Table 4 D5A 70°C thermoplastic insulated and sheathed fl at cable with protective conductor (copper conductors).

Current-carrying capacity (A)Ambient temperature: 30°C

Conductor operating temperature: 70°C

Conductor cross-sectional area

Reference Method 100 (above a plasterboard ceiling covered by thermal insulation not exceeding 100 mm in thickness)

Reference Method 101 (above a plasterboard ceiling covered by thermal insulation exceeding 100 mm in thickness)

Reference Method 102# (in a stud wall with thermal insulation with cable touching the inner wall surface)

Reference Method 103# (in a stud wall with thermal insulation with cable not touching the inner wall surface)

Reference Method C* (clipped direct)

Reference Method A* (enclosed in conduit in an insulated wall)

Voltage drop (per ampere per metre)

1 2 3 4 5 6 7 8

(mm2) (A) (A) (A) (A) (A) (A) (mV/A/m)

1 13 10.5 13 8 16 11.5 44

4 27 22 27 17.5 37 26 11

16 57 46 63 42.5 85 57 2.8

A* For full installation method refer to Table 4A2 Installation Method 2 but for Twin fl at and earth cableB* For full installation method refer to Table 4A2 Installation Method 20 but for Twin fl at and earth cable100# For full installation method refer to Table 4A2 Installation Method 100101# For full installation method refer to Table 4A2 Installation Method 101102# For full installation method refer to Table 4A2 Installation Method 102103# For full installation method refer to Table 4A2 Installation Method 103Wherever practicable, a cable is to be fi xed in a position such that it will not be covered with thermal insulation. Regulation 523.7, BS 5803-5: Appendix C: Avoidance of overheating of electric cables, Building Regulations Approved document B and Thermal insulation: avoiding risks, BR 262, BRE, 2001 refer.

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2 Appendix 2 – Popular cables: current rating tables from BS 7671: 2008 Appendix 4

Three tables are included here, BS 6004 PVC thermosetting fl at twin and earth, XLPE thermosetting single-core

and XLPE thermosetting armoured. These tables are not complete and have been added to make this book,

particularly Chapter C, readable. For complete tables, please refer to BS 7671: 2008.

Guide to the W

iring Regulations: 17th E

dition IEE

Wiring R

egulations (BS 7671: 2008) D

arrell Locke

© 2008 John W

iley & Sons L

td. ISBN

: 978-0-470-51685-0

268

Guid

e to the Wiring R

egulations

Samples from Table 4 E1A Single-core 90°C thermosetting insulated cables, unarmoured, with or without sheath (copper conductors).

Current-carrying capacity (A)Ambient temperature: 30°C

Conductor operating temperature: 90°C

Conductor cross-sectional area

(enclosed in conduit in thermally insulating wall, etc.)

(enclosed in conduit on a wall or in trunking, etc.)

(clipped direct) (in free air or on a perforated cable tray etc horizontal or vertical, etc.)

(in free air)

Touching Spacedby one cable diameter

2 cables, single-phase a.c. or d.c.

3 or 4 cables, three-phase a.c.

2 cables, single-phase a.c. or d.c.

3 or 4cables, three-phase a.c.

2 cables, single-phase a.c. or d.c. fl at and touching

3 or 4 cables, three-phase a.c. fl at and touching or trefoil

2 cables, single-phase a.c. or d.c. fl at

3 cables, three-phase a.c. fl at

3 cables, three-phase a.c trefoil

2 cables, single-phase a.c. or d.c. or 3 cables three-phase a.c. fl at

Horizontal Vertical

1 2 3 4 5 6 7 8 9 10 11 12

(mm2) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A) (A)

1.5 9 17 23 20 25 23 — — — — —

50 158 141 198 175 228 209 242 216 207 275 246

120 278 249 354 312 413 379 437 400 383 500 454

300 486 435 603 514 743 681 783 736 703 902 833

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269

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ices

Samples from Table 4 E4A Multicore 90°C armoured thermosetting insulated cables (copper conductors).

Current-carrying capacity (A)

Air ambient temperature: 30°CGround ambient temperature: 20°C

Conductor operating temperature: 90°C

Conductor cross-sectional area

(clipped direct) (in free air or on a perforated cable tray etc, horizontal or vertical)

(direct in ground or in ducting in ground, in or around buildings)

1 two-core cable, single-phase a.c. or d.c.

1 three- or 1 four- core cable, three-phase a.c.

1 two-core cable, single-phase a.c. or d.c.

1 three- or 1 four- core cable, three-phase a.c.

1 two-core cable, single-phase a.c. or d.c.

1 three- or 1 four- core cable, three-phase a.c.

1 2 3 4 5 6 7

(mm2) (A) (A) (A) (A) (A) (A)

6 62 53 66 56 53 44

25 146 124 152 131 116 96

50 219 187 228 197 164 135

185 515 441 539 463 343 281

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