Earth Wire Query

[jamiegleave]

Hi
My wife has recently purchased a shop and we're gutting it out at the moment for a refit. The fuse box/mains come in towards the front of the shop; however the water pipe is right at the back of the shop 3 rooms away.

There is a G&Y earth wire connecting to the mains and running all the way along the centre of the wall, through the other two walls and connecting up to the incoming water pipe. The whole arrangement is messy.

The questions I have are:
1 - Is this wire necessary?
2 - If yes, then is there a better way arranging this?

Thanks

Jamie

 

[tonyelectric]

What you describe sounds like a main bonding conductor, this connects the water pipework to the main electrical earth thus making the earth voltage at the pipework equipotential (same as) that of the electrical earths and therefore removing any risk of shock between the two.

Yes it is needed, but how the wire makes its journey through the shop is really a matter of suiting the building layout, your question makes me think you are considering removing the partitions, in which case it's OK to re-route the earth. It would be considered poor practice to join an earth, we usually use continuous runs, but if a joint has to occour make sure you use the correct joiner (not a standard chock block)

The size of wire should be 10mm2 based on table 54.8 and reg 544.1.1 assuming your main neutral is not larger than 35mm2

Reg 544.1.2 makes the specification that the connection to the water main be no more than 600mm/60cm after it enters the building.

 

[Chri5]

Water and gas service needs earth bonding. A 10mm sq earth cable between the main earth terminal in the building and within 600mm of the main water cock and the customer side of the gas meter.

The main terminal is either a silver coloured metal block or inside the main fuse board. At the main terminal you should have an earth from the mains head (subject to earthing type TNS / TNCS / TT), a 16mm sq earth to the CU and then the 2 x earths mention above.

The earths are a safety requirement as as such they are essential.

It is perfectly acceptable to renew or replace them as a DIY job, so re routing they above ceiling, under floor or under plaster / behind plaster board is allowed.

The logic behind the earthing of gas / water pipes is to ensure that there is even potential between all pipe work.

 

[MalcofArabia]

Unfortunately if it turns out to be a main protective bonding conductor then it will need to remain.

There is a good possibility that it may have to be upgraded in line to the 17th edition of the regs if the shop as not had any electrical upgrading since 2008.

IMO I would contact a loacal electrician to give you advise on this. He would also advise you on how best to run the cable as well

 

[jamiegleave]

Thanks for the responses.

I know a good electrician who did some wiring in my house. I will get him to come round and take a look. I wouldn't mind having some of the light switches moved as well so I'll see what he says.

The shop we have got is filthy and the wiring looks immaculately clean, so I suspect it is a fairly recent job. The G&Y wire is pretty thick and attached at the base of the floor where the water pipe enters the building, but the manner in which it has been installed is particularly messy. There seems no reason why it couldn't have been clipped to the corners of the wall and run around the edges (as the phone line is) to make this all a bit tidier.

Cheers