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Default boiler earthing?

Hello,

My old (oil fired) boiler had a 4mm^2 (ish) earth wire that ran from
the copper oil line back to the CU.

When the (non-oftec) plumber recently installed the new boiler, this
was not reconnected. I am having an oftec plumber coming to sign
everything off. Should I connect the earth before he comes and for my
own safety?

The boiler is earthed but only through the 6A flex.

In my last house the (gas) boiler had all the pipes cross bonded
immediately beneath it. None of the pipes going to or from this boiler
are. I don't think the CH pipes are earthed anywhere. Should they be?

Thanks,
Stephen.
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Default boiler earthing?

In article ,
Stephen writes:
Hello,

My old (oil fired) boiler had a 4mm^2 (ish) earth wire that ran from
the copper oil line back to the CU.


That's the service bonding.
Nowadays, it should be 10mm˛, IIRC.

When the (non-oftec) plumber recently installed the new boiler, this
was not reconnected. I am having an oftec plumber coming to sign
everything off. Should I connect the earth before he comes and for my
own safety?


I would have thought so, but I'm not expert in oil fired boiler
matters and any special requirements on them.

The boiler is earthed but only through the 6A flex.

In my last house the (gas) boiler had all the pipes cross bonded
immediately beneath it. None of the pipes going to or from this boiler
are. I don't think the CH pipes are earthed anywhere. Should they be?


They probably are in or adjacent to the bathroom -- that's where it's
normally done.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]
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Default boiler earthing?


"Stephen" wrote in message
...
Hello,

My old (oil fired) boiler had a 4mm^2 (ish) earth wire that ran

from
the copper oil line back to the CU.

When the (non-oftec) plumber recently installed the new boiler, this
was not reconnected. I am having an oftec plumber coming to sign
everything off. Should I connect the earth before he comes and for

my
own safety?

The boiler is earthed but only through the 6A flex.

In my last house the (gas) boiler had all the pipes cross bonded
immediately beneath it. None of the pipes going to or from this

boiler
are. I don't think the CH pipes are earthed anywhere. Should they

be?

Thanks,
Stephen.


My OFTEC oil installer fitted my boiler but didn't bond the incoming
oil pipe, despite me querrying it. My NICEIC electrician certifying
the whole electrical installation insisted on 10mm bonding back to the
main earth point at the CU. Mind you I can (and actually have in a
previous posting) cite several errors of fact on his certificate !!!)
The boiler per se is only earthed via the copper plumbing which is
bonded and its own electrical connection 2.5mm earth.

AWEM

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Default boiler earthing?

Stephen wrote:

My old (oil fired) boiler had a 4mm^2 (ish) earth wire that ran from
the copper oil line back to the CU.


That would be the main equipotential bond for the incoming service (i.e.
oil pipe)

When the (non-oftec) plumber recently installed the new boiler, this
was not reconnected. I am having an oftec plumber coming to sign
everything off. Should I connect the earth before he comes and for my
own safety?


All incoming services in metallic pipes should be included in the main
equipotential bonding.

For TN-C-S and TN-S installations this is usually 10mm^2 earth single.
For TT it can be 6mm^2

See:

http://wiki.diyfaq.org.uk/index.php?...ng_and_Bonding

The boiler is earthed but only through the 6A flex.


That is fine.

In my last house the (gas) boiler had all the pipes cross bonded
immediately beneath it. None of the pipes going to or from this boiler
are. I don't think the CH pipes are earthed anywhere. Should they be?


Where is the boiler? Where was it in the last place?

Generally speaking you would expect to see supplementary equipotential
bonding in places that pose an special risk (bath / shower rooms, pool /
saunas etc). There is no harm in have supplementary bonding between its
connections, however there is in many cases no absolute requirement for
it. Note that supplementary bonds do not need to be either earthed, or
connected back to the main CU earth terminal.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
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| John Rumm - john(at)internode(dot)co(dot)uk |
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Default boiler earthing?

On Sun, 4 Jan 2009 18:31:05 -0000, "Andrew Mawson"
wrote:

My OFTEC oil installer fitted my boiler but didn't bond the incoming
oil pipe, despite me querrying it. My NICEIC electrician certifying
the whole electrical installation insisted on 10mm bonding back to the
main earth point at the CU


My OFTEC chap didn't comment that it's not connected. However since
the wire is there I will connect it. I'll have to be careful though as
I assume the 10mm micorobore pipe is more easily damaged if I
overtighten the clamp.

Thanks.
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Default boiler earthing?

On Sun, 04 Jan 2009 21:12:29 +0000, John Rumm
wrote:

Where is the boiler? Where was it in the last place?

Generally speaking you would expect to see supplementary equipotential
bonding in places that pose an special risk (bath / shower rooms, pool /
saunas etc). There is no harm in have supplementary bonding between its
connections, however there is in many cases no absolute requirement for
it. Note that supplementary bonds do not need to be either earthed, or
connected back to the main CU earth terminal.


It is in the kitchen, exactly where the old one was. Thinking about it
it's all copper pipe around the boiler but after 2 metres it turns
plastic, so I'm not sure that bonding would do much, except in the
immediate area of the boiler.

Is supplemental bonding supposed to be 10mm^2 too? I am not going to
do it (unless you tell me otherwise) but I ask out of curiosity.

Thanks.
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Stephen wrote:
On Sun, 04 Jan 2009 21:12:29 +0000, John Rumm
wrote:

Where is the boiler? Where was it in the last place?

Generally speaking you would expect to see supplementary equipotential
bonding in places that pose an special risk (bath / shower rooms, pool /
saunas etc). There is no harm in have supplementary bonding between its
connections, however there is in many cases no absolute requirement for
it. Note that supplementary bonds do not need to be either earthed, or
connected back to the main CU earth terminal.


It is in the kitchen, exactly where the old one was. Thinking about it
it's all copper pipe around the boiler but after 2 metres it turns
plastic, so I'm not sure that bonding would do much, except in the
immediate area of the boiler.


In "special locations" (of which a kitchen is *not* one - part P lumps
it in with them, but the wiring regs do not), the question to ask, is
are the pipes capable of introducing a potential into the room from
elsewhere. In you case it sounds like the answer is "no".

To quote the OSG (16th edtn): "There is no specific requirement in BS
7671 to supplementary bond the following

kitchen pipes, sinks or draining boards

metal furniture in kitchens

metal pipes and wash hand basins in domestic locations
other than bathrooms."

Is supplemental bonding supposed to be 10mm^2 too? I am not going to
do it (unless you tell me otherwise) but I ask out of curiosity.


Where there is no mechanical protection for the bonding conductors,
4.0mm is commonly used. Where you are bonding a circuit protective
conductor, then you should not use a smaller CSA wire than that of the
CPC - however domestic wires with CPCs larger than 4.0mm are not common
(only 16mm^2 for T&E)

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/
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