RCD protection to garage.

[Bobble23]

Hello. I'm afraid I've got a bit of a hole in my knowledge about RCD's so if anyone could reassure me/tell me I'm completely wrong about this I'd appreciate it.

Was called to a customer today to put an extra socket in his garage and found that it's fed by twin 1.5mm with no cpc, buried in conduit, from a 15A breaker on the house's RCD-protected DB. The garage is about 25m away so I think he just about gets away with the 1.5mm volt-drop wise, but obviously I need to sort out the lack of any earth in the garage.

I'm planning on just putting in an earth spike and an RCD garage unit in place of the two MCB's he has in the garage at the minute. My (possibly stupid) question is, would having a separate earthing arrangement at the garage when it's fed from an RCD-protected breaker in the house cause nuisance trips or anything in the house? There are no free non-RCD spaces in the house DB, though I suppose I could Henley block the supply if I had to.

Any other glaring holes in my plan would be gratefully received.

Thanks.

 

[7029 dave]

With the op's info , bang straight in with new swa sub, why muck about.

 

[Meggerman]

With the op's info , bang straight in with new swa sub, why muck about.

Of course you are right, but we do like to discuss all angles

 

[GLENNSPARK]

I'd start by doing a Ze at the garage DB and see what the reading was like!

Zdb....

 

[7029 dave]

Of course you are right, but we do like to discuss all angles

Ha Ha, megger, no point ........ about with a rusty old bit of conduit madness.!!

 

[amckay]

Hello. I'm afraid I've got a bit of a hole in my knowledge about RCD's so if anyone could reassure me/tell me I'm completely wrong about this I'd appreciate it.

Was called to a customer today to put an extra socket in his garage and found that it's fed by twin 1.5mm with no cpc, buried in conduit, from a 15A breaker on the house's RCD-protected DB. The garage is about 25m away so I think he just about gets away with the 1.5mm volt-drop wise, but obviously I need to sort out the lack of any earth in the garage.

I'm planning on just putting in an earth spike and an RCD garage unit in place of the two MCB's he has in the garage at the minute. My (possibly stupid) question is, would having a separate earthing arrangement at the garage when it's fed from an RCD-protected breaker in the house cause nuisance trips or anything in the house? There are no free non-RCD spaces in the house DB, though I suppose I could Henley block the supply if I had to.

Any other glaring holes in my plan would be gratefully received.

Thanks.

I'd go for submain SWA. What is the load on the garage? Is it being used as a garage or a gym or a granny flat? I'd go for Henley block straight to garage with a IP CU

 

[davesparks]

It's on a 15A fuse, take a wild guess at what the load could be!

 

[amckay]

It's on a 15A fuse, take a wild guess at what the load could be!

That is what is there at the minute. What is he planning to use the new socket/s for?

 

[davesparks]

Could be anything, it's a socket!

It'll still be fused at 15A whatever happens!

 

[R G]

Just to out to B&Q and get yourself an extension lead , its gotta be better than using that whatever happens ,, WTF,,