My electric wiring was done 25+ years ago, professionally, has given
no problems, and is still in good nick. Earthing, not now compliant,
is by bonding to the incoming pipe containing power supply cable and
that seemed to work. British Gas heating advisor came to estimate for
new boiler 2 weeks ago, tested my power sockets with 'socket and see'
device and everything ok including earthing. Engineer came to install
boiler yesterday and his 'socket and see' showed earthing totally
inadequate. Electrician then did more detailed measurement and got
earth reading of 5ohms (should be under 1).
Boiler installation now postponed, and can't really expect anyone to
work on faults on existing boiler
The one possibly relevant thing in the two weeks has been gas mains in
street and up to house renewed with plastic pipes. Meter is now
outside with no earthing. Equipotential bonding is on copper pipe pipe
from meter just after it enters house. It used to be on consumer side
of internal meter. Could it be that the iron supply pipe (now
disconnected) on other (supply) side of the meter was providing some
of the earthing for my electricity circuits through the equipotential
bonding?
Power distribution is responsibilty of Scottish Power who are coming
to look at fitting fused cut out and mains earthing terminal at
consumer supply point. Apparently so many people are finding their
houses non-compliant for various reasons that I may join a 6-8 week
queue. Anyone know of any other compliant answer to getting earthing
to required level?

Thanks

Toom

On 26 Aug, 18:26, Toom Tabard wrote:
My electric wiring was done 25+ years ago, professionally, has given
no problems, and is still in good nick. Earthing, not now compliant,
is by bonding to the incoming pipe containing power supply cable and
that seemed to work. British Gas heating advisor came to estimate for
new boiler 2 weeks ago, tested my power sockets with 'socket and see'
device and everything ok including earthing. Engineer came to install
boiler yesterday and his 'socket and see' showed earthing totally
inadequate. Electrician then did more detailed measurement and got
earth reading of 5ohms (should be under 1).
Boiler installation now postponed, and can't really expect anyone to
work on faults on existing boiler
The one possibly relevant thing in the two weeks has been gas mains in
street and up to house renewed with plastic pipes. Meter is now
outside with no earthing. Equipotential bonding is on copper pipe pipe
from meter just after it enters house. It used to be on consumer side
of internal meter. Could it be that the iron supply pipe (now
disconnected) on other (supply) side of the meter was providing some
of the earthing for my electricity circuits through the equipotential
bonding?
Power distribution is responsibilty of Scottish Power who are coming
to look at fitting fused cut out and mains earthing terminal at
consumer supply point. Apparently so many people are finding their
houses non-compliant for various reasons that I may join a 6-8 week
queue. Anyone know of any other compliant answer to getting earthing
to required level?

Thanks

Toom

Convert the installation to TT.

On 26/08/2010 19:08, cynic wrote:
On 26 Aug, 18:26, Toom wrote:
My electric wiring was done 25+ years ago, professionally, has given
no problems, and is still in good nick. Earthing, not now compliant,
is by bonding to the incoming pipe containing power supply cable and
that seemed to work. British Gas heating advisor came to estimate for
new boiler 2 weeks ago, tested my power sockets with 'socket and see'
device and everything ok including earthing. Engineer came to install
boiler yesterday and his 'socket and see' showed earthing totally
inadequate. Electrician then did more detailed measurement and got
earth reading of 5ohms (should be under 1).
Boiler installation now postponed, and can't really expect anyone to
work on faults on existing boiler
The one possibly relevant thing in the two weeks has been gas mains in
street and up to house renewed with plastic pipes. Meter is now
outside with no earthing. Equipotential bonding is on copper pipe pipe
from meter just after it enters house. It used to be on consumer side
of internal meter. Could it be that the iron supply pipe (now
disconnected) on other (supply) side of the meter was providing some
of the earthing for my electricity circuits through the equipotential
bonding?
Power distribution is responsibilty of Scottish Power who are coming
to look at fitting fused cut out and mains earthing terminal at
consumer supply point. Apparently so many people are finding their
houses non-compliant for various reasons that I may join a 6-8 week
queue. Anyone know of any other compliant answer to getting earthing
to required level?

Thanks

Toom

Convert the installation to TT.

Which will mean RCD protection and an earth spike.

"Toom Tabard" wrote in message
...
My electric wiring was done 25+ years ago, professionally, has given
no problems, and is still in good nick. Earthing, not now compliant,
is by bonding to the incoming pipe containing power supply cable and
that seemed to work. British Gas heating advisor came to estimate for
new boiler 2 weeks ago, tested my power sockets with 'socket and see'
device and everything ok including earthing. Engineer came to install
boiler yesterday and his 'socket and see' showed earthing totally
inadequate. Electrician then did more detailed measurement and got
earth reading of 5ohms (should be under 1).
Boiler installation now postponed, and can't really expect anyone to
work on faults on existing boiler
The one possibly relevant thing in the two weeks has been gas mains in
street and up to house renewed with plastic pipes. Meter is now
outside with no earthing. Equipotential bonding is on copper pipe pipe
from meter just after it enters house. It used to be on consumer side
of internal meter. Could it be that the iron supply pipe (now
disconnected) on other (supply) side of the meter was providing some
of the earthing for my electricity circuits through the equipotential
bonding?
Power distribution is responsibilty of Scottish Power who are coming
to look at fitting fused cut out and mains earthing terminal at
consumer supply point. Apparently so many people are finding their
houses non-compliant for various reasons that I may join a 6-8 week
queue. Anyone know of any other compliant answer to getting earthing
to required level?


After 25 years you should seriously consider getting the entire wring system
checked by NICEIC qualified electrician.

Peter Crosland

After 25 years you should seriously consider getting the entire wring
system checked by NICEIC qualified electrician.

NICEIC are not the only game in town (albeit they try to give the
impression people they are). Other "competent persons schemes" for
installers who can do all electrical installation work are BSI, EC
Certification Limited / ELECSA and NAPIT

(And yes, I dislike monopolies and wannabe monopolies.)

--
Robin
PM may be sent to rbw0{at}hotmail{dot}com

On Aug 26, 8:41*pm, "Peter Crosland" wrote:
After 25 years you should seriously consider getting the entire wring system
checked

Conflict of interest between those doing the PIR and those wanting to
do remedials :-)

It sounds like the OP has 2 issues.
#1 - Supplier earth is not up to specification.
A DNO provided earth must be maintained once provided. If the supply
is TN-C-S (PME) or TN-S the Ze figure should be 0.35ohm or 0.80ohm
respectively. If the figure is 5ohms then it sounds like the old metal
gas pipe was contributing to the earth.
An out of spec earth is an emergency callout if it is sufficiently out
of spec, 5ohms will mean no more than 50 Amps will flow to earth which
will either result in a delayed fault disconnect (seconds to minutes)
or no fault disconnect (40A shower). Worse 5ohms may be at "15mA earth
fault loop impedance (EFLI) tester current" and I would much rather
know a 25Amp high current EFLI test result - which might potentially
be substantially worse.

#2 - Main Equipotential Bonding is not current.
I suspect the cold water pipe if metal is providing some or all of the
earth, it comes down to what supply type the OP has.

At present I would want...
1 - an electrician to check a) what supply type you have b) whether
the cold water main is providing the earth b) whether MEB is correct
(mainly re in-place and sized correctly).
2 - a conversion to a "TT supply" temporarily or permanently, that is
where you have individual RCBO or a front-end RCD to the whole house
temporarily until the DNO can get their bods on your doorstep.

If you have an electrical fault with a 5ohm Ze then insufficient
current may flow to blow a fuse or trip a circuit breaker, either in a
timely manner (0.4-4sec disconnect depending on appliance type/risk)
or without overheating wiring sufficiently to cause permanent damage
or fire.

Personally I would have a spark check and convert to TT as mentioned.

On 26 Aug, 22:08, "js.b1" wrote:
On Aug 26, 8:41*pm, "Peter Crosland" wrote:

After 25 years you should seriously consider getting the entire wring system
checked

Conflict of interest between those doing the PIR and those wanting to
do remedials :-)

It sounds like the OP has 2 issues.
#1 - Supplier earth is not up to specification.
A DNO provided earth must be maintained once provided. If the supply
is TN-C-S (PME) or TN-S the Ze figure should be 0.35ohm or 0.80ohm
respectively. If the figure is 5ohms then it sounds like the old metal
gas pipe was contributing to the earth.
An out of spec earth is an emergency callout if it is sufficiently out
of spec, 5ohms will mean no more than 50 Amps will flow to earth which
will either result in a delayed fault disconnect (seconds to minutes)
or no fault disconnect (40A shower). Worse 5ohms may be at "15mA earth
fault loop impedance (EFLI) tester current" and I would much rather
know a 25Amp high current EFLI test result - which might potentially
be substantially worse.

#2 - Main Equipotential Bonding is not current.
I suspect the cold water pipe if metal is providing some or all of the
earth, it comes down to what supply type the OP has.

At present I would want...
1 - an electrician to check a) what supply type you have b) whether
the cold water main is providing the earth b) whether MEB is correct
(mainly re in-place and sized correctly).
2 - a conversion to a "TT supply" temporarily or permanently, that is
where you have individual RCBO or a front-end RCD to the whole house
temporarily until the DNO can get their bods on your doorstep.

If you have an electrical fault with a 5ohm Ze then insufficient
current may flow to blow a fuse or trip a circuit breaker, either in a
timely manner (0.4-4sec disconnect depending on appliance type/risk)
or without overheating wiring sufficiently to cause permanent damage
or fire.

Personally I would have a spark check and convert to TT as mentioned.

Thanks to all who replied - that info is very helpful. I'm not an
electrician and don't understand all the terminology used. But, if a
gas meter can allow a continuous circuit - can it? - metal pipe to
metal chassis to metal pipe? - then that might explain the earth
working the other way into the iron supply pipe and maybe helping
earth the whole house, and why the change to unearthed external meter/
box with plastic supply pipe has made a difference. I called in a
senior technician from the gas supply renewal company, who are still
working in the area - he seemed unaware that that could happen and is
interested to find out if it is the cause - I suppose few folk happen
to have their earthing tested just before and then just after gas
supply replacement.

The distribution company - Scottish power - did send someone within
hours. They checked it out, but merely said I should phone their
installation dept and arrange for them to come fit their standard
earthing. He did mention the possibility of getting an electrician to
fit a front end RCD meantime but said they'd need to check if that was
regs 17? compliant - he wasn't sure.

Neither boiler company nor distribution company electrician gave any
indication of it being an emergency situation, and there is this
mention of 6 - 8 week queue for rectification of many similar
situations - mainly where water mains and water supply pipes have been
replaced with plastic. Scottish Power are sending someone to look at
rectification in detail - but not for several days.

I'll look into it further, since a more urgent temporary or permanent
fix seems needed, both for safety and to get boiler installation
moving.

Thanks again to all

Toom

"Toom Tabard" wrote in message
...
On 26 Aug, 22:08, "js.b1" wrote:
On Aug 26, 8:41 pm, "Peter Crosland" wrote:

I called in a
senior technician from the gas supply renewal company, who are still
working in the area - he seemed unaware that that could happen and is
interested to find out if it is the cause - I suppose few folk happen
to have their earthing tested just before and then just after gas
supply replacement.

The distribution company - Scottish power - did send someone within
hours. They checked it out, but merely said I should phone their
installation dept and arrange for them to come fit their standard
earthing. He did mention the possibility of getting an electrician to
fit a front end RCD meantime but said they'd need to check if that was
regs 17? compliant - he wasn't sure.



The senior technician is just being dozy, either deliberately or otherwise.
In other areas, where utility companies work on gas or water mains replacing
metal with plastic they send postcards out to affected consumers warning
them of the possible effect on earthing and that it is the customer's
responsibility to sort out.

You have done well to get the supplier to do something about it,
particularly if they will sort out the earthing for free. In many areas,
DNOs seem to try to deny they provided the original earth and so it becomes
the consumer's problem via his electrician.

Regards
Bruce

On 27 Aug, 13:56, "BruceB" wrote:
"Toom Tabard" wrote in message

...





On 26 Aug, 22:08, "js.b1" wrote:
On Aug 26, 8:41 pm, "Peter Crosland" wrote:

I called in a
senior technician from the gas supply renewal company, who are still
working in the area - he seemed unaware that that could happen and is
interested to find out if it is the cause - I suppose few folk happen
to have their earthing tested just before and then just after gas
supply replacement.

The distribution company - Scottish power - did send someone within
hours. They checked it out, but merely said I should phone their
installation dept and arrange for them to come fit their standard
earthing. He did mention the possibility of getting an electrician to
fit a front end RCD meantime but said they'd need to check if that was
regs 17? compliant - he wasn't sure.

The senior technician is just being dozy, either deliberately or otherwise.
In other areas, where utility companies work on gas or water mains replacing
metal with plastic they send postcards out to affected consumers warning
them of the possible effect on earthing and that it is the customer's
responsibility to sort out.


Electricians and Scottish Power have both mentioned the problems when
earthing is to water pipes and these are replaced with plastic. Senior
technician for gas pipe replacement said they leave cards when they
notice the equipotential bonding on internal gas pipes isn't there, or
isn't correctly positioned. Position of mine isn't quite correct but
that wasn't mentioned at the time or by card. It does seem they could
be a bit more consumer friendly about it, but general approach seems
to be they do their bit and don't want to get involved in the
complexities which exist or which they cause in individual houses. In
my case, if equipotential bonding was incidentally giving earthing to
my electrics through old metal gas pipe, then that seemed something
technician didn't know about, but wanted to find out more. Said he
knew all about equipotential bonding for gas regulations, but did know
domestics electrics.

You have done well to get the supplier to do something about it,
particularly if they will sort out the earthing for free. *In many areas,
DNOs seem to try to deny they provided the original earth and so it becomes
the consumer's problem via his electrician.

I gather from engineer that what is supplied and fitted at consumer
unit is at customers expense and it's a good earner for the company.
Any problem with earthing from there to distribution system is
company's problem/expense.

Regards

Toom

Peter Crosland wrote:
"Toom Tabard" wrote in message
...

After 25 years you should seriously consider getting the entire wring
system checked by NICEIC qualified electrician.

I disagree. Provided that the circuits have not been modified in the time
being, there is no need to have it checked.

Be aware, the Elfins are about.