metal board on tt system

[jstephens251]

Hi all,

where does it say in the regs that you can't use metal consumer units on a tt arrangement? been told this by a couple of people but can't find anything

cheers

 

[Deleted member 9648]

It doesnt...but logically if supply tails which are not RCD protected pass through the metal enclosure the high Zs on a TT will not enable the protective device to operate if the tails short onto the enclosure...therefore it will not comply with the required disconnection time.....Metal enclosures can be used if the tails are RCD protected,or if measures are taken to ensure the tails cannot short onto the enclosure,such as insulated bushes and clamping the tails to ensure they are secure and cant move.
Generally it is easier and preferable to use an insulated enclosure.

 

[sjm]

Wirepuller is absolutely right!

 

[mechelec]

The regulation you are looking for is 531.4.1