Earth bonding to gas and water supply - help!

[TYA]

I'm having an existing loft conversion extended, with new shower to replace the existing electric one. The first thing the electrician told me was that the cable to the existing shower was not the required 10mm (despite the existing shower being a 9.5kw) so we'd need to either drop to an 8.5kw or - better - run a mixer shower off the combi boiler, which is just feet away.

Happy to do that. However, there's been an unexpected curveball in the apparent need to have earth bonding to the gas and water supply, which will either mean a nightmare in the house taking up floorboards etc and running cable under the house (although I don't think there's room for anyone to crawl through with the cable) or running it outside the house to the (externally located) gas meter/supply.

Bloke down the road in identical house to mine just had his loft done - similar, shower off combi boiler - and says he didn't have/need anything like this (and was signed off by building regs). We had a kitchen put in in 2005 and the combi boiler in 2006 so I'd have thought this might have come up before. Is the electrician missing something, could there be bonding anywhere else... or is it a new regs thing??

 

[Richard Burns]

I would probably direct you to this link to the Electrical Safety Council website that has a pdf leaflet covering earthing and bonding and the regulatory requirement that these are up to date if there is any electrical work done.

 

[Tim]

Unfortunatly you cant compare your house with the bloke down the road.

The regs have changed since 2005 (17th edition 2008) and bonding requirements have changed.

Bonding MUST be up to scratch before any electrical work can be completed.

Check out this from the esc.

http://www.esc.org.uk/fileadmin/use...s/Earthing___Bonding-_web_ready-_13-09-12.pdf

As for your shower cable, it may not have been up to the job for your old shower, do you know what size it is?

Tim

 

[TYA]

thanks Tim - I'm not sure about the old cable but yes, does sound like it wasn't up to the job of the old shower.

 

[SirKit Breaker]

The electrician is in my opinion giving good advice about the shower, in some cases 6.0mm will do, but in most cases it wont, but in any event electric showers are crap, so the combi option is sensible.

You will need to include more detail regarding your current set up with the gas/water bonding, and there are a lot of considerations that can be taken into account.

Cheers..........Howard

PS just re read your post.Is the problem not being able to bond within 600mm of entry to the property? if it is then the electrician needs to remember that the regs are GUIDANCE only, and he needs to bond as close as possible to the point of entry to the property. It is far more important that it is bonded, than where it is bonded. Fault current travels very fast, and it wont take it noticeably longer to travel 40 feet, than it would to travel 600mm.

 

[TYA]

I think he is giving good advice, yeah - he said the combi option would be better too. I was wondering whether the previous installers/electricians could have put the bonding somewhere we hadn't thought of, but no, it does appear that there isn't any. I've looked at the gas meter/supply and there's no sign of anything coming off it/leading to it. I think we may have to run the cable outside the house, as discreetly as possible

 

[SirKit Breaker]

I think he is giving good advice, yeah - he said the combi option would be better too. I was wondering whether the previous installers/electricians could have put the bonding somewhere we hadn't thought of, but no, it does appear that there isn't any. I've looked at the gas meter/supply and there's no sign of anything coming off it/leading to it. I think we may have to run the cable outside the house, as discreetly as possible

See above i have editted it

 

[TYA]

the problem is that the fuse box is at the rear of the house (in the kitchen), the stopcock/water supply enters in the downstairs bathroom (adjoins kitchen), but the gas supply/meter is right round the front of the house, outside, hence the need to connect to there. Running under the floorboards is problematic (we have laminate flooring/tiles, plus I don't think there's enough room under the floorboards for someone to crawl with the cable), so external may be the way to go

 

[Tim]

A person doesnt have to crawl in with the cables, they can be pulled in using rods, but as theres laminate and tiles its unlikly it will be a useable route.
External is the way to go, it will be cheaper and cause less destruction.

Tim

 

[TYA]

many thanks

 

[Stroppy]

Apprentice + electric cattle prod. Geddin there, boy...

 

[GLENNSPARK]

to the O/P..

will people please please stop refering to such things as `earth bonding`...
earth bonding is straight out of the pat teating `engineers` handbook....
in reality earth bonding does not exist....as both earthing and bonding perform too entirely different functions...

 

[Stroppy]

[/pedant]

 

[Geordie Spark]

[/pedant]

That's wot hangs from the ceiling with a bulb on the end innit?

 

[Geordie Spark]

I think he is giving good advice, yeah - he said the combi option would be better too. I was wondering whether the previous installers/electricians could have put the bonding somewhere we hadn't thought of, but no, it does appear that there isn't any. I've looked at the gas meter/supply and there's no sign of anything coming off it/leading to it. I think we may have to run the cable outside the house, as discreetly as possible

He's right.

A half decent Thermostatic or Pressure Balanced shower run off a Combi knocks spots off the best electric shower in terms of temperature and volume of water.