# Earth Bonding at New Boiler

#### btctworld

we have just had a new combi boiler installed in the airing cupboard the plumber has bonded all 5 pipes together with 5 earth clamps should a 10mm earth cable now be run from the cu to these pipes?

thanks brett

this is actually a Corgi rule, not an electrical one (there are electrical rules relating to Main Bonding of the water and gas mains when they come into your house; and Supplementary Bonding of metalwork in your bathroom, but not for boilers). You may do better to repost in the plumbing and heating section as "Corgi Boiler Earth Bonding" or some heading to attract their attention.

Regutation 413-02-02: In each installation main equipotentioal bonding conductors complying with sectoin 547 shall connect to the main earthing terminal for that installations extreneous-conductive-parts including the following:

(iv) Central heating and air conditioning systems

but I've heard that in a domestic kitchen, where you already have the water and gas mains bonded, and don't need supplementary bonding, the Corgi folk do additional bonding round the boiler, that was what I was thinking of. do you think I've got it wrong?

I am unsure.

If the gas is main bonded then the gas pipe should act as a continuous connection to the boiler aswell. Cross bonding the pipes at the boiler might be an idea as a potential could exist between the different pies if the boiler was removed for some reason.

RF - that reg you quote gives examples of items that ~may~ need main eq bonding.

All extraneous conductive parts that introduce a potential into the equipotential zone requires main eq bonding - If the pipework was run outside from one building to another for example, the cent heat would then be an extraneous conductive part.

Ive always had a problem interpretting this regulation about main equipotential bonding of central heating pipes.

Some people argue the point that cental heating is not an incomming service such as gas, water, oil etc.

Think Lectrician states a good point and one that does make sense in connecting an equipotential bond to central heating pipes, although there is nothing wrong with bonding them anyway which is common these days.

RMS

RMS said:
Ive always had a problem interpretting this regulation about main equipotential bonding of central heating pipes.

Some people argue the point that cental heating is not an incomming service such as gas, water, oil etc.

Think Lectrician states a good point and one that does make sense in connecting an equipotential bond to central heating pipes, although there is nothing wrong with bonding them anyway which is common these days.

RMS

I know exactly what you mean, clear as mud. I take it to mean that extraneous conductive parts which can introduce a potential (inc earth potential) into the equipotential zone need to be main eq. bonded. A central heating boiler in a house which is inside the eq. zone imo does not pose the risk of introducing a potential, hence from the electrical regs pov does not require main eq. bonded. If the copper pipework goes outside the equipotential zone then this pipework then requires main eq bonding.

Most new boilers have a metal plate to which all the pipes are connected, doing away with the need to do this.

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