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We are getting a new kitchen fitted. An electrical survey has been carried out by the compnay installing kitchen. they have said that, our brand new and recently fitted, boiler needs a earth wire running from itself to the fusebox. As does our old gas meter. This is a pain as they are at the outermost parts of our property and the fusebox is central. So it will mean cables/wires all over the place.

Surely the boiler can be earthed via nearby mains powerpoint ? Or straight out to the literal earth via the nearby water stop cock/water meter.

Any advice from electricians, or those with electrical knowledge ? I am based in the UK, and apparently these are health safety regulations, although I think they are somewhat open to interpretation.

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I don't think you can earth via the water pipes any more, so that's not an option.

I would have thought that the boiler would be earthed through it's normal power supply, but if it needs a separate earth then as for the meter you could run the earth wire around the outside of the house to the fuse box (or as far as possible) which would minimise both the disruption in installing it and the amount of wire you need.

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  • you're correct, I was told by a professional that grounding to a water pipe is no longer valid due to the use of PVC and plastic piping, the grounding point is no longer valid. – user45 Sep 14 '10 at 13:37
  • UK building regs may allow it (at least they did when they built my current home, under current regs) – Rowland Shaw Sep 21 '10 at 20:47
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I know you're in the UK, but I'll answer for the US in case someone there has the same question.

Boilers and furnaces must be powered by a separate, grounded circuit.

Any metal piping system that is likely to become energized must be bonded, including gas pipes, but the equipment grounding conductor run with the circuit conductors feeding a gas appliance "shall be permitted to serve as the bonding means":

NEC 250.104 (B) Other Metal Piping.

Where installed in or attached to a building or structure, a metal piping system(s), including gas piping, that is likely to become energized shall be bonded to the service equipment enclosure, the grounded conductor at the service, the grounding electrode conductor where of sufficient size, or the one or more grounding electrodes used. The bonding jumper(s) shall be sized in accordance with 250.122, using the rating of the circuit that is likely to energize the piping system(s). The equipment grounding conductor for the circuit that is likely to energize the piping shall be permitted to serve as the bonding means. The points of attachment of the bonding jumper(s) shall be accessible.

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If you have a hot wire that has come loose that touches the gas pipe you want it to cause a short so that it trips the breaker, or blows a fuse.

If the wire doesn't trip a breaker, or blows a fuse, the wire can start eating away at the pipe. I have actually seen an armored cable eat away at a piece of ductwork, all the wile giving off a glow where the two met.

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Keep in mind what the goal is. The goal is to have everything bonded to a common ground to avoid voltage differentials due to different ground potentials. Like others have said, older installations might use water pipes, but newer usually can't. I don't know your local code, but that's the goal that the code is pushing you towards.

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