time delayed main switch?

[ukpablo]

just been to a quote for new bathroom refurb , new board done, hi integrity crabtree starbreaker CU in place.

TT system

split rcd with 2 ways etc. 30 MA on each, all tested ok.
no time delayed main switch, just standard 100A main switch.
Does this require one as it is split load?
the install is 6 months old?

 

[Guest123]

No, as all circuits have 30mA RCD protection already a 100A 100mA TD RCD is not required.

Unless the CU is metalclad in which case the tails may need additional protection also, as it is a TT system.

 

[malcolmsanford]

Not sure what you mean by a time delayed main awitch, are you meaning a S type or time delayed RCD?

On an TT system you would have had a 100mA RCD for lighting etc and then your 30mA for sockets as required on the old 16th. as the new 17th edition now requires that the majority of circuits are now RCD protected this as changed the requirements for TT systems quite a lot.

 

[ukpablo]

its for a 17th board. This is my first TT board (job) since being registered etc.
Just wanted to double check, i thought that the split dual 30MA rccb's were adequate, but was unsure.
i see alot of 100MA literature banded out about TT systems main switches etc so needed to clarify what im talkin about.

 

[Deleted member 19807]

the use of the "s" type was to provide discrimination as any fault would take out both the 30 and 100ma rccb's if no time delay was used, now we have 17th edition you would normally just have a main switch and 2 x 30ma rccb's