Discuss Correct Type-S Upfront RCD for 3Ph TT System in the Electrical Forum area at ElectriciansForums.net

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Raptor0014

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Hi all,

Doing an EICR on a property which is 3Ph in and then 3 x Single phase boards from that. However it's on a TT System and doesn't have a upfront 100mA RCD and I am not aware of any reason why one wouldn't be required.

So I am just wondering if this MCG one will suffice into an enclosure.


Or if I need to go balls to the wall and get this Hager one


Obviously I need to justify to the client the cost difference and brand name I know Hager is great kit. But if anyone has any other recommendations it would be appreciated.
 
The MCG one appears to be time delayed type AC, hager seems to be non time delayed type A

I'd want to fit a time delayed type A really, but you also need to be sure the down stream boards have non time delayed rcds upfront, or rcbos with switched neutral
Good spot on the non-time delay. Never noticed that at first after I got sidetracked at the price. 😂

The downstream boards are 2 x Hager split load dual 30mA RCD

The third board is a fuse box RCBO board
 
Last edited:
Good spot on the non-time delay. Never noticed that at first after I got sidetracked at the price. 😂

The downstream boards are 2 x Hager split loaf dual 30mA RCD

The third board is a fuse box RCBO board

Ok, so you need to make sure those fusebox rcbos are switched neutral, if not, in the event of a N-E fault the neutral will still remain in circuit after the rcbo has tripped, likely taking out the big boy upfront
 
Ok, so you need to make sure those fusebox rcbos are switched neutral, if not, in the event of a N-E fault the neutral will still remain in circuit after the rcbo has tripped, likely taking out the big boy upfront

All fusebox RCBOs are now switched neutral. I don't think they make any other kind now.
 
I am right is thinking it has to be a time delayed RCD upfront and not just a 100mA or 300mA?
Yes it would need to be time delayed... but looking at that, if both hager boards out of shot below the head are plastic, I'd just swap out that switch fuse for a new one and fit a 2pole 100ma type S / type A in there as that things got basic insulation hanging out it's arse anyway.
 
Yes it would need to be time delayed... but looking at that, if both hager boards out of shot below the head are plastic, I'd just swap out that switch fuse for a new one and fit a 2pole 100ma type S / type A in there as that things got basic insulation hanging out it's arse anyway.
I've got that and a lot lot more coded on the EICR 👍

I thought the tails needed to be protected regardless if the CU was plastic (they are)? Hence going to swap out the basic isolator and make that a 3P 100a 100mA time delayed RCD?

Or have I got that wrong?
 

Reply to Correct Type-S Upfront RCD for 3Ph TT System in the Electrical Forum area at ElectriciansForums.net

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