ZS

rapier · Dec 6, 2008

Evening Guys

Just 2nd fixed a barn conversion at work.

We are using a 3 phase board as the suppliers provided 3 phase.

So on all the circuits we used rcbo's at c type i dont know why my boss choose c types.

So when i came to test the installation the results are fine but are over on max zs but not by a million miles away.

So are these fine as there protected on a rcbo or should i tell my boss to convert to b type rcbo's.

Thanks guys

maddfridge · Dec 7, 2008

rapier said:
Evening Guys

Just 2nd fixed a barn conversion at work.

We are using a 3 phase board as the suppliers provided 3 phase.

So on all the circuits we used rcbo's at c type i dont know why my boss choose c types.

So when i came to test the installation the results are fine but are over on max zs but not by a million miles away.

So are these fine as there protected on a rcbo or should i tell my boss to convert to b type rcbo's.

Thanks guys

hi there

i seem to recall where the ZS cannot be met the installation of a rcd was required to give additional protection in order to meet the required disconnection time of the protective device where this CANNOT be achieved. his would explain the rcbo

I would look again at the ZS as did you take into account the R! and R2 correction factors for temperatue Guidance not no3 page 107 appendix B
I have done 2391 testing but have not come across this in the course was in the old guidance notes just had a look shows we cannot always kep up with the changes

cheers