TT System main isolator switch

[yelloperil]

I am installing a consumer unit on a TT system, The "ON site Guide" says it must have a 100ma time delayed RCD as its main isolation switch, but I have since been told that this has changed and I can use a standard 30ma RCD. Which one is correct?

 

[chloebear]

Hi, If you are installing a new consumer unit onto a TT installation I would assume that it is a Dual RCD protected CU with an RCD as the main switch incorporated within the CU.