In article ,
Adrian Brentnall adrian-the papers and the writes:
HI Andrew
Thanks for the comments

On 30 May 2005 21:04:57 GMT, (Andrew
Gabriel) wrote:

In article ,
Adrian Brentnall adrian-the papers and the writes:
HI all
We're hoping to sell our bungalow soon in anticipation of an overseas
move (Ireland).

With this in mind - I'm looking around the property at things that a
surveyor might find fault with. Have already sorted all the little
'nearly finished' bits of decorating that we've lived with for 5 years
g - and now thinking about the electrics.

Although the electrics are now much improved over the original
slightly dodgy, elcb, wire-fused installation - one thing that I never
got round to was the earth bonding. I've read up in the faq, and in my
Which DIY Electrics book - but I'd like some clarification if
possible..?

1) We use Calor (big red cylinders) for gas. Should the incoming
small-bore gas pipe be bonded back to the main earth ? - even though
the gas hob and the gas cooker are both connected to mains earth via
their own 3-core cables....

Yes.

OK - that's going to be a pain !
I can get access to the gas pipe outside near the gas bottles, or
inside, near the gas hob. If I connect at the hob then it's going to
be a mare to get back to the main earth bonding terminal....

There isn't a meter (obviously) or a valve - other than the ones on
the cylinders themselves.

This part of the installation was done by the previous occupant.... -
wish I'd known about the need to do the bonding on the gas pipe when I
had the kitchen floors up 4 years ago - would have been very easy back
then..... not so easy now......

The bonding can be done outside the house.
Actually this is common for (natural) gas supplies with
outside meters. I'm not familiar with how a bottled gas
supply is setup.

2) The airing cupboard looks like a good place to connect 'everything
to everything' - as the central heating piping, the power-shower
pipework, the solar heating pipework, the general hot & cold pipework
and the water pipe from the well all pass through here. Is bonding
here a good idea / acceptable ?

Not necessarily. Bonding of sevices which come in from outside
needs to be done where they enter the house, normally within
300mm on house side if the isolating valve.

The incoming water supply is in black 'alkathene' pipe from the well
- turns into copper pipe in the airing cupboard....... - I've
described the gas supply arrangement above.

OK. Just include it in the bathroom bonding then.

Bonding of bathroom
pipework should be done in the bathroom or immediately adjacent
to it. If the airing cupboard fits one or both of these
requirements, then that's a good option. Otherwise it's a waste
of time as you will still need to bond at the required locations.

I'm interested in the 'immediately adjacent' option. The power shower
mixer is fed through the wall from the airing cupboard by copper pipe
- can I bond it in the airing cupboard ? Likewise, the jacuzzi is fed
by a short pipe-run from the airing cupboard - should this be bonded
at the pipe under the taps... or can it be done in the airing cupboard

Assuming it's all copper pipework, either.
The bath (if metal) needs bonding to the tap pipework too,
which is normally done under the bath.

3) I understand that bonding hot, cold and exposed metalwork is
necessary at kitchen sinks and bathrooms - does this bonding need to
extend back to the common mains earth by the switchboard ?

Only necessary in bathrooms. People often do kitchens too, but
there's no requirement to do so in the regs.

OK - that's worth knowing - thanks !

The bonding should
be to the earths of local circuits -- a dedicated earth conductor
back to the switchboard is not required for bathroom bonding (it
is for the service bonding above). Normally, 4mm² earth cable
is used for bonding, but that can be dropped down to 2.5mm² if
the cable is protected from damage.

OK - I can come throught the bathroom wall to reach a 13A socket in
the hall - so I could pick up the earth from there ?

It should be to the circuits which supply the bathroom such as
the lighting circuit. Ring circuit is less likely to supply
anything in the bathroom, but if it does, then bond that too.

4) Anything else I should be thinking of ?? regarding a possible
survey...

Water supply should be bonded back to the main earth terminal
too.

Even in the case of the well-water system I've described. The only
place that the water pipe from the well goes is into the cold storage
tank in the loft...

Service bonding should be done with 10mm² earth wire.

OK - so that's just for the gas, then ??

Yes.

The main earth terminal should be connected to the supplier's
earth connection with 16mm² earth wire.

Yes - that's done - but thanks for reminding me...

--
Andrew Gabriel