Outbuilding on non RCD side of C/U?

[Nicebloke]

If running power to an outbuilding (usually a garage at the bottom of someones garden), I normally run it from the non RCD side of the C/U in the house and then put a 2 way RCD protected C/U in the garage. I was however, told that I can no longer do this as it must be connected to an RCD in the house C/U. I was also told that any outbuilding more than 20 metres away from a house must have it's own TT system?

 

[Pete999]

If running power to an outbuilding (usually a garage at the bottom of someones garden), I normally run it from the non RCD side of the C/U in the house and then put a 2 way RCD protected C/U in the garage. I was however, told that I can no longer do this as it must be connected to an RCD in the house C/U. I was also told that any outbuilding more than 20 metres away from a house must have it's own TT system?

where did you hear this?

 

[Leesparkykent]

Was the person a DI?

 

[telectrix]

DI as in Dumb Idiot?

 

[Nicebloke]

It was from my part P assessor.

 

[stevethesparks]

As him to show you where it states that particular regulation. What scheme are you with?

 

[Octopus]

Then he needs to read and understand the regs.

Which scheme

 

[kingeri]

What a load of tripe. Jeez.

 

[Wilko]

Surely yours is the best method, as long as the cable has physical protection (i.e. not triggering the cables in walls reg). Having RCD in series is difficult to discriminate and the longer the run the more impact it has. A lamp blows in building2 at night and trips a board in building1 a 100m away creating an unnecessary hazard, imho.
Edit : and the reverse, a problem in building1 takes out RCD covering building2

 

[Nicebloke]

I am with Stroma. With regards an outbuilding requiring its own TT system if it's more than 20 metres from the house, I can't see where he got this from?

 

[telectrix]

I am with Stroma. With regards an outbuilding requiring its own TT system if it's more than 20 metres from the house, I can't see where he got this from?

out of a chinese christmas cracker, i'd assume. what a load of bollox.

 

[Wilko]

On a lighter note - I've recently done a Zs = 18 Ohm TT install. So this could be my chance, my calling and perhaps what I'm best suited to - hitting rods with big hammers

 

[Octopus]

I am with Stroma. With regards an outbuilding requiring its own TT system if it's more than 20 metres from the house, I can't see where he got this from?

Which regs did he use to back up his view?

 

[The Ghost]

While there are arguments to support that thinking, it is only one way of doing it, there is guidance to download called Exporting PME. If I put an RCD at the house I personally would only use that for the cable protection supplying the garage and do a TT at the garage. I understand the DNO do not like exporting PME too far from the origin as it may defeat their PME. But the above is not set in stone, there are other approaches.
Exporting Pme - http://www.electriciansforums.co.uk/resources/exporting-pme.101/

 

[Nicebloke]

Which regs did he use to back up his view?

I didn't question him on what regs he got his info from, and I will just stick with what I have done in the past.