exporting earth

[bahco]

right lads need a bit of advice which seems to be a bit of a grey area among the sparks ive spoke to.

ok so tncs pme supply, from consumer unit via 32a 100ma rcbo to garge about 20 mtrs away fed it 6mm 3c swa, in the garage 3 way metalclad board 63a rcd main switch 2 circuits, lighting 6a sockets 32a final ring

now the confusing bit, im led to belive you cannot use the earthing system in your house to earth your garage.... reason is your garage is not in the same equipotential zone as your house.

so would i need to install a earth rod for the garage or is it ok as it is?

any help or advice would be great

thanks lads

 

[Spudnik]

All cleared up here:

http://---------------/Publish/Wire...matters_electrical_installations_outdoors.pdf

 

[bahco]

cheers for that jason

after reading through it all it never mentions the earth apart from the tt system options, so im taking it must be ok to export the earth.

im using it as my nic assesment so think i might give them a ring just to check there view on it first, ive heard off another nic member they dont like it.

thanks for the link though

 

[Spudnik]

Its the DNO's who are not keen on the idea.

If the neutral becomes disconnected then in effect you have lost ALL earthing in the garage, whereas in the house its still just about earthed still via the main bonding.

But yes, have a word with the NICEIC (if you can get through).

 

[professional]

There is no reason why you cannot export your earth - the only other consideration would be if the garage contained metal services pipework, in which case you would have to ensure adequate CSA of armouring since the 6mm core within the cable would be insufficient. For PME any structural steel would also need to be bonded via 10mm squared copper core (or EQUIVALENT).

 

[mrloy99]

right lads need a bit of advice which seems to be a bit of a grey area among the sparks ive spoke to.

ok so tncs pme supply, from consumer unit via 32a 100ma rcbo to garge about 20 mtrs away fed it 6mm 3c swa, in the garage 3 way metalclad board 63a rcd main switch 2 circuits, lighting 6a sockets 32a final ring

now the confusing bit, im led to belive you cannot use the earthing system in your house to earth your garage.... reason is your garage is not in the same equipotential zone as your house.

so would i need to install a earth rod for the garage or is it ok as it is?

thanks lads

anyhelp or advice would be great

hi bahco,I think that earthed equipotential zone tecnospeak has been done away with now 17th(could be wrong)But I think you idea is fine.I think you could get away without the 100ma in the house though.There is no mention of any exposed metalwork in your statement so I don't think you need worry about earth rod,and TT,but if you did go TT you would need to use an insulated C.U. in garage.

 

[bahco]

thanks for all the replys lads

just to clear up a few points mentioned the garage is block with no steel work at all, there are no copper pipes inside or outside the garage, there is a tap outside the garage but its all fed in plastic pipe so no worries there.

i decided on a 100ma rcbo in the house consumer unit because originally it was on the 30ma protected side of the board, so when i tripped the rcd main switch in the garage it also tripped the house rcd, so just put a 32a 100ma rcbo in.

still need to ring the nic just to check, dont want to get to assesment day then he's not happy.

cheers again

 

[beaver74]

thanks for all the replys lads

just to clear up a few points mentioned the garage is block with no steel work at all, there are no copper pipes inside or outside the garage, there is a tap outside the garage but its all fed in plastic pipe so no worries there.

i decided on a 100ma rcbo in the house consumer unit because originally it was on the 30ma protected side of the board, so when i tripped the rcd main switch in the garage it also tripped the house rcd, so just put a 32a 100ma rcbo in.

still need to ring the nic just to check, dont want to get to assesment day then he's not happy.

cheers again

make sure the 100mA is a time delayed one

 

[bahco]

yeah it is mate

 

[mrloy99]

yeah it is mate

not sure why you need a 100ma in house at all....you don't have TT

 

[bahco]

the reason i put a 100ma in the house is because when i tripped the rcd in the garage the house 30ma rcd tripped as well.

so i just put a 100ma time delayed in the house.

do you not think that was the best way?

cheers

 

[Spudnik]

30 mA RCBO in main CU up front of garage supply, standard Cu in garage.

All RCD protection catered for in one place.

No discrimination issues either.

 

[bahco]

yeah did think of that, but i thought it would be better putting the 100ma on the house unit, might score some browny points with the nic inspector

 

[Spudnik]

Fair enough!

 

[wattsup]

If it's grey, use an earth spike, £3 quid, and a couple of quid for the cable...no reason to quibble. Though I do understand the why?
I know one 'inspector' could not wire a christmas tree, he cannot understand the regs, he regular missinterprets..yet he works for the local mafia, aka the council