RCD on garage electrics
Discussion
There's no RCD on my garage which is at the end of my garden.
In the garage is a consumer unit. From garage to house is a 6mm armoured cable, both ends go into metal boxes with a brass gland. Then 6mm twin and earth from the armoured cable (which terminates at the back of the house) to the house consumer unit on a C40 circuit breaker.
With the RCD is it as simple as replacing the main inlet switch on the consumer unit with an RCD one? Wouldn't mind the whole house being protected. Fit one in the home consumer unit and the garage one?
Also should I earth spike at the garage if I'm fitting an RCD there? It's a 1930's house so I think it has earth from the supply company and also earthed at the gas pipe. But the main power cable from the street is pretty rotted and the earth I think is carried via the shield, so maybe it needs to be tested for good earth?
In the garage is a consumer unit. From garage to house is a 6mm armoured cable, both ends go into metal boxes with a brass gland. Then 6mm twin and earth from the armoured cable (which terminates at the back of the house) to the house consumer unit on a C40 circuit breaker.
With the RCD is it as simple as replacing the main inlet switch on the consumer unit with an RCD one? Wouldn't mind the whole house being protected. Fit one in the home consumer unit and the garage one?
Also should I earth spike at the garage if I'm fitting an RCD there? It's a 1930's house so I think it has earth from the supply company and also earthed at the gas pipe. But the main power cable from the street is pretty rotted and the earth I think is carried via the shield, so maybe it needs to be tested for good earth?
Aha, yes the RCD needs to protect selected areas, I remember now (I did once work in the trade yonks ago). I'd rather do it properly, so maybe get my electrician in and get him to do the entire consumer unit. I'm guessing cost isn't too bad as consumer units are cheap and it can't be much over a day to fit it all and maybe an extra day for testing, misc work, and tidying up etc.
So with the more modern consumer units, could they have seperate RCDs for different areas, example seperate RCD for the garage, so that any garage mishaps don't take the house out? I know some people have a seperate unit to feed their garage (ie henly block and seperate tails), but I'm trying to reduce the number of devices under my stairs because a toilet will be fitted there some some so it all needs to fit into the small space that will be left once the toilet goes in.
Also, am I right that the earth on these 1930's houses goes back to the power station as well as connecting to the gas pipe plus bonding at the boiler? Also my new central heating will be all poly pipe so what happens to the rules on bonding under the boiler if it's all plastic? The pipes at the boiler will be copper but then all goes to poly.
So with the more modern consumer units, could they have seperate RCDs for different areas, example seperate RCD for the garage, so that any garage mishaps don't take the house out? I know some people have a seperate unit to feed their garage (ie henly block and seperate tails), but I'm trying to reduce the number of devices under my stairs because a toilet will be fitted there some some so it all needs to fit into the small space that will be left once the toilet goes in.
Also, am I right that the earth on these 1930's houses goes back to the power station as well as connecting to the gas pipe plus bonding at the boiler? Also my new central heating will be all poly pipe so what happens to the rules on bonding under the boiler if it's all plastic? The pipes at the boiler will be copper but then all goes to poly.
Yabu said:
Make sure they put in a 3rd amendment compliant DB in and go for individual rcbos if you get a new board fitted in the house. Have you hot a water supply to the garage?
Whats a DB?And what are RCBOs?
There's no water at all in the garage. There will be a water butt collecting roof rain water for washing hands and watering garden, probably unsuitable for car washing, I think rain water is not clear.
Ganglandboss said:
The latest version of BS 7671 (the IEE regs)requires RCDs on cables buried in walls, circuits in bathrooms and socket circuits, so every circuit in a typical house will need RCD protection. The issue of a single RCD covering the whole installation causing a nuisance is actually covered by the regs; it is not permitted. You may use either a split board with two banks of circuits on two RCDs, but the Gucci method has been suggested. An RCBO is an RCD and MCB combined in one device (residual current breaker with overload). This means every circuit has its own RCD, so it won't affect others if there is a fault on just one.
If there is plastic pipe, there is no need for bonding. Even with copper the rules have now been relaxed. If there is electrical continuity through the pipework and the electrical installations comply with the current regs, supplementary bonding is not required.
Most urban supplies will have a supplier's earth facility. Rural installations with overhead supplies do not have a supplier's earth, due to the risk of earth conductors being blown down. In these cases, an earth electrode is required. Suppliers' earth facilities will comprise a TN-S (where there is a live and neutral conductor, and a metallic outer sheath providing the earth), or a TN-C-S (where the earth and neutral are the same conductor until being split at the incoming position). The connection to the gas pipe is a main bonding conductor - there should be one to the water, unless it is plastic. The electrician will check the integrity of the supplier's earth (if applicable) with an earth loop impedance test.
Thanks, all clear now. These Gucci consumer units probably not cheap, but I'll see what the electrician says.If there is plastic pipe, there is no need for bonding. Even with copper the rules have now been relaxed. If there is electrical continuity through the pipework and the electrical installations comply with the current regs, supplementary bonding is not required.
Most urban supplies will have a supplier's earth facility. Rural installations with overhead supplies do not have a supplier's earth, due to the risk of earth conductors being blown down. In these cases, an earth electrode is required. Suppliers' earth facilities will comprise a TN-S (where there is a live and neutral conductor, and a metallic outer sheath providing the earth), or a TN-C-S (where the earth and neutral are the same conductor until being split at the incoming position). The connection to the gas pipe is a main bonding conductor - there should be one to the water, unless it is plastic. The electrician will check the integrity of the supplier's earth (if applicable) with an earth loop impedance test.
Ganglandboss said:
A typical dual RCD consumer unit will cost around £80 as a kit, complete with a selection of MCBs that suit a typical house. A bare unit will cost about £30 and then around £8-10 per MCB. If you want RCBOs, they'll cost about £35 each, so you are looking at over £400 for a 12 way set up before labour.
That's a big price difference! Could a dual RCD unit power the house and detached garage? Or would the two RCDs be used by the house leaving no spare for the garage? Or could the garage utilise the ring mains RCD?So it does sound like a basic "Garage consumer unit with RCD" which Screwfix sell for £20 would solve things. I could fit that in no time, but what concerns me is whether it needs to be tested. Could I just put in an extra earth spike at the garage to ensure it's properly earthed or should I get in the electrician who can do the earth test etc as well?
Sorting out my house consumer unit can be another task then. RCD protection sounds good to me because I am pretty reckless so the extra protection would be good and I can take the opportunity to have the consumer unit moved to make space for under staits toilet.
Gandland and people, thank you very much for advice.
Sorting out my house consumer unit can be another task then. RCD protection sounds good to me because I am pretty reckless so the extra protection would be good and I can take the opportunity to have the consumer unit moved to make space for under staits toilet.
Gandland and people, thank you very much for advice.
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