rcd's in metal enclosures on TT

[great68]

Is it correct on a TT supply any rcd's at the main distribution should be in a plastic enclosure and is there a reg for this ?

 

[spinlondon]

It's not in BS7671. It's something to do with the DNO.

Best check with your local DNO, see what they say.

 

[sparkyt]

not always, as long as there is no contact between tails and the metal db then there is no risk of a short to earth before the rcd. Use paxolin to insulate between the two. either method is ok, i did a farm last week and the main 300ma rcd went into a plastic enclosure before the installation because there was no neat way to get tails into trunking/board setup correctly.

 

[steptoe]

I would say it may well be considered best practice to use a plastic enclosure,

and remember to disconnect the neutral with you protective devices if necessary(ie DP RCBOs).

tho I am wondering what we are meant to do in 3phase, I have never ever seen a 4pole RCBO in the UK.!!!!!

 

[Andy™]

not sure about RCBO either, but you can easily get RCD's





click pics for more info

 

[batty]

I would not use a metal enclosure on TT system. In the old 16th regs it would be ok as you would have a 100 or 30mA rcd as main switch. Tails could be put through plastic or nylon gland so if anything where to come in contact with enclosure after Rcd it would trip. With the 17th main switch could be just double pole so anything coming in contact with busbar too enclosure could be a serious fire risk.

Batty