TLC Electrical Supplies

16th Edition (reference only) – NOW superseded by the 17th Edition IEE Regulations.

Cables, conduits and trunking

	4.1 - Cable insulation materials	4.4 - Cable supports, joints and terminations
	4.2 - Cables	4.5 - Cable enclosures
	4.3 - Cable choice	4.6 - Conductor and cable identification


4.3.1 - Cable types	4.3.8 - Protection by semi-enclosed (rewirable) fuses
4.3.2 - Current carrying capacity of conductors	4.3.9 - Cable rating calculation
4.3.3 - Methods of cable installation	4.3.10 - Special formulas - grouping factor calculation
4.3.4 - Ambient temperature correction factors	4.3.11 - Cable volt drop
4.3.5 - Cable grouping correction factors	4.3.12 - Harmonic currents and neutral conductors
4.3.6 - Thermal insulation correction factors	4.3.13 - Low smoke-emitting cables
4.3.7 - When a number of correction --------- factors applies	4.3.14 - The effects of animals, insects and plants

4.3.8 - Protection by semi-enclosed (rewirable) fuses

If the circuit concerned is protected by a semi-enclosed (rewirable) fuse the cable size will need to be larger to allow for the fact that such fuses are not so certain in operation as are cartridge fuses or circuit breakers. The fuse rating must never be greater than 0.725 times the current carrying capacity of the lowest-rated conductor protected.

In effect, this is the same as applying a correction factor of 0.725 to all circuits protected by semi-enclosed (rewirable) fuses. The ambient temperature correction factors of {Table 4.3} are larger than those for other protective devices to take this into account.

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Extracted from The Electricians Guide Fifth Edition
by John Whitfield

Published by EPA Press Click Here to order your Copy.

Click here for list of abbreviations