On 01/09/2012 11:24, David WE Roberts wrote:
Read the Wiki, just need to double check.

Whole house re-plumb in plastic.
So (apart from directly around the combi) there shouldn't be any metal in
the hot and cold plumbing until you get to the taps.
So in turn I assume that there is no bonding requirement for the H&C system
as there seems no way that a faulty earth in an appliance (including
bathroom lighting etc.) can cause current to flow through a person to earth
via taps or water pipes.

Yup. The fundamental question is "can the thing introduce a potential
into the equipotential zone", so cosmetic stubs of metal pipe in an all
plastic system can't.

Majority of the CH will be in plastic - the only copper is likely to be the
incoming gas main up to the combi, a short run of 15mm pipe at entry/exit to
the combi, and probably short tails on the radiators going below floor to
join the plastic main piping for flow and return.

The main EQ bonding should be in place - so gas main where it enters,
and water main if it does so in metal.

So earth at the CU should be bonded to the gas pipe as close to the entry
into the property as possible (by the meter which is on the outside wall).

Generally yes. Sometimes the connection is made on the consumers
pipework in the meter box itself. On installs like mine where the meter
feeds 14m of underground plastic pipe before it enters the building, it
is done where it transitions to copper as it enters.

Electrics around the combi should be bonded to the copper gas pipe.

Is the combi in a bath or shower room? If not it sounds like there is
not much requirement to bond the combi to anything.

Oh, and the gas hob should be bonded to the gas pipe as well.

Can't think why...

Probably anything electrical in theoretical touching distance of a gas pipe
(or the hob?) in the kitchen.

EQ bonding is not generally required in a kitchen since its not an area
of special risk (you are less likely to be wet and naked one generally
assumes ;-)

Is there anything else that should be bonded?

Not that jumps out at me...

With all plastic the traditional problem of routes to earth being created by
metal gas and water pipes seem to have gone away.

Indeed.


--
Cheers,

John.

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