Hello all
Can anyone please let me know, if BS7671 clearly specifies the wiring requirements for sub fuse boxes?
Hi... welcome to the magical electrical forumbulator...
To expand a bit on this part of your question:-
BS7671 gives guidance how to design, install, test and certify that an electrical installation will be capable carrying the expected load currents,
and maximum fault currents for all circuits of an installation without endangering people, property or livestock.
It pretty much covers everything wiring related in a domestic dwelling from the electricity meter onward...
The types of cable, installation methods, and protective devices will be governed by various factors including external influences due to the environment they are installed in, the length of circuits and ensuring permissible volt-drop is not exceeded...
But BS7671 does not actually say you must use a specific cable for a particular application...
as very often there are multiple ways to achieve compliance with BS7671.
(some relate to cost, aesthetic appearance, diversity considerations, ring, radial and/or parallel conductors etc.. etc..)
BUT...
it does clearly state what type of certification should be used for different types of works:-
New circuits, Consumer Units, Re-wires etc... Will require an "Electrical Installation Certificate". (EIC)
Additions and alterations to an existing circuit..... A "Minor Works Certificate" can be used.. (MWC)
Inspecting and testing of an existing installation without doing any alteration work..... An "Electrical Installation Condition Report" will be issued giving an overall summary if an installation is satisfactory or unsatisfactory for continued use. (EICR)
If someone, (AKA a cowboy electrician), has issued an EICR for installing a new sub-main.... then personally I would not trust much they say, anymore than I would trust my sister-in-law's friend who is a hairdresser for any electrical advice!!!