Hi

Just completing a house wiring job, I've now got myself a tad confused
about what size of earth cable I should be using to bond the incoming
gas and water pipes to the main earth near the electric meter. I've
already used 10mm, but have got myself worried that this isn't big
enough and would rather get it right now than have the inspector tell
me to change it later (it's not a trivial task, as the gas and
electric meters are at opposite ends of the house!)

The electricity installation is new (and not yet connected to the CU),
and it's PME. The earth cable is completely protected mechanically
along its length... is there any other info needed to assess the
correct earth size? Or do I need to ask the supply company, ahich is
what the stuff at www.tlc-direct.co.uk seems to be suggesting?

Many thanks
David

"Lobster" wrote in message
om...
Hi

Just completing a house wiring job, I've now got myself a tad confused
about what size of earth cable I should be using to bond the incoming
gas and water pipes to the main earth near the electric meter. I've
already used 10mm, but have got myself worried that this isn't big
enough and would rather get it right now than have the inspector tell
me to change it later (it's not a trivial task, as the gas and
electric meters are at opposite ends of the house!)

The electricity installation is new (and not yet connected to the CU),
and it's PME. The earth cable is completely protected mechanically
along its length... is there any other info needed to assess the
correct earth size? Or do I need to ask the supply company, ahich is
what the stuff at www.tlc-direct.co.uk seems to be suggesting?

Many thanks
David

From the mains service head you need to run 10 mm csa' green/yellow sheathed
conductors. On all the other supplementary bonding you would use 6 mm csa'
green/yellow sheathed conductors.

On 25 May 2004 11:09:27 -0700, (Lobster) strung
together this:

Hi

Just completing a house wiring job, I've now got myself a tad confused
about what size of earth cable I should be using to bond the incoming
gas and water pipes to the main earth near the electric meter.

10mm cables for the equipotential, i.e. gas, water and any other services and
structural metalwork, and 4mm for the supplementary if required, i.e. cross
bonding in the bathroom.

The earth cable is completely protected mechanically
along its length

I'd be very surprised if it was.


is there any other info needed to assess the
correct earth size?

Nope, that's it.
--

SJW
A.C.S. Ltd

"Lurch" wrote in message ...

On 25 May 2004 11:09:27 -0700,
(Lobster) strung together this:

is there any other info needed to assess the correct earth size?

Nope, that's it.

That's not quite true because of the note above Table 54H in the regs which
says "Local public electricity supply network conditions may require a
larger conductor" - so, strictly speaking, you should check with the
relevant distributor to see if they require a larger size.

I've no idea how often this applies, but when I used to have dealings with
the old Eastern Electricity on such matters they certainly preferred the use
of 16mm^2 main bonding. The issue may also come up in London, where fault
levels tend to be higher.

Given that you need a reel of 16 mm^2 cable for the main earthing conductor,
you may as well use the same size for main bonding, just to be on the safe
side, and avoid having to carry a reel of 10mm^2 as well.

--
Andy

On Wed, 26 May 2004 00:02:53 +0100, "Andy Wade"
strung together this:

Nope, that's it.

That's not quite true because of the note above Table 54H in the regs which
says "Local public electricity supply network conditions may require a
larger conductor" - so, strictly speaking, you should check with the
relevant distributor to see if they require a larger size.

Fair point, however it is 'most likely'' that 10mm will suffice. I
doubt anyone at wherever it is that the OP rings will have a clue what
he's on about anyway!

I've no idea how often this applies, but when I used to have dealings with
the old Eastern Electricity on such matters they certainly preferred the use
of 16mm^2 main bonding. The issue may also come up in London, where fault
levels tend to be higher.

Can't say as I've ever come across any of that, just goes to show.

Given that you need a reel of 16 mm^2 cable for the main earthing conductor,
you may as well use the same size for main bonding, just to be on the safe
side, and avoid having to carry a reel of 10mm^2 as well.

Hmmm, you can, I'll stick to 10mm thanks! I can't see someone rewiring
there own house buying 100m of 16mm earth to use 3m of it though! I
think you're aiming your comments at the profesionals now, shouldn't
that be moved OT!
--

SJW
A.C.S. Ltd

In article , BigWallop
writes

"Lobster" wrote in message
. com...
Hi

Just completing a house wiring job, I've now got myself a tad confused
about what size of earth cable I should be using to bond the incoming
gas and water pipes to the main earth near the electric meter. I've
already used 10mm, but have got myself worried that this isn't big
enough and would rather get it right now than have the inspector tell
me to change it later (it's not a trivial task, as the gas and
electric meters are at opposite ends of the house!)

The electricity installation is new (and not yet connected to the CU),
and it's PME. The earth cable is completely protected mechanically
along its length... is there any other info needed to assess the
correct earth size? Or do I need to ask the supply company, ahich is
what the stuff at www.tlc-direct.co.uk seems to be suggesting?

Many thanks
David

From the mains service head you need to run 10 mm csa' green/yellow sheathed
conductors. On all the other supplementary bonding you would use 6 mm csa'
green/yellow sheathed conductors.


Though if you have a drum of 10 use 10 save ending up with 2 half drums
--
Z
Remove all Zeds in e-mail address to reply.

In article , Lurch
writes
On Wed, 26 May 2004 00:02:53 +0100, "Andy Wade"
strung together this:

Nope, that's it.

That's not quite true because of the note above Table 54H in the regs which
says "Local public electricity supply network conditions may require a
larger conductor" - so, strictly speaking, you should check with the
relevant distributor to see if they require a larger size.

Fair point, however it is 'most likely'' that 10mm will suffice. I
doubt anyone at wherever it is that the OP rings will have a clue what
he's on about anyway!

I've no idea how often this applies, but when I used to have dealings with
the old Eastern Electricity on such matters they certainly preferred the use
of 16mm^2 main bonding. The issue may also come up in London, where fault
levels tend to be higher.

Can't say as I've ever come across any of that, just goes to show.

Given that you need a reel of 16 mm^2 cable for the main earthing conductor,
you may as well use the same size for main bonding, just to be on the safe
side, and avoid having to carry a reel of 10mm^2 as well.

Hmmm, you can, I'll stick to 10mm thanks! I can't see someone rewiring
there own house buying 100m of 16mm earth to use 3m of it though! I
think you're aiming your comments at the profesionals now, shouldn't
that be moved OT!
--

SJW
A.C.S. Ltd

Even then many companies as per NIECIC use 10 throughout.
--
Z
Remove all Zeds in e-mail address to reply.

(Lurch) wrote in message ...
On 25 May 2004 11:09:27 -0700, (Lobster) strung together this:

Just completing a house wiring job, I've now got myself a tad confused
about what size of earth cable I should be using to bond the incoming
gas and water pipes to the main earth near the electric meter.

10mm cables for the equipotential, i.e. gas, water and any other services and
structural metalwork, and 4mm for the supplementary if required, i.e. cross
bonding in the bathroom.

Thanks everyone, that's a relief!

The earth cable is completely protected mechanically
along its length

I'd be very surprised if it was.

Maybe you're right there... "completely protected mechanically" is a
rather vague phrase I keep seeing in the relevant documentation on
this topic, as being one of the criteria for deciding the size of
cable to use. I took it to mean that the earth cable was hidden from
sight/possible damage - mine is inside stud partitions or under
floorboards along its whole length, rather than being attached to
skirting boards(!) or whatever.

David

On 25 May 2004 23:49:16 -0700,
(Lobster) strung together this:

Maybe you're right there... "completely protected mechanically" is a
rather vague phrase I keep seeing in the relevant documentation on
this topic, as being one of the criteria for deciding the size of
cable to use. I took it to mean that the earth cable was hidden from
sight/possible damage - mine is inside stud partitions or under
floorboards along its whole length, rather than being attached to
skirting boards(!) or whatever.

I thought that would be the case, it's not mechanically protected
then. Mechanically protected would mean it was enclosed in conduit or
trunking throught its entire length, including its passage through
walls and the like. That's something else you've learnt today! ;-)
--

SJW
A.C.S. Ltd

Lurch wrote:
On 25 May 2004 23:49:16 -0700,
(Lobster) strung together this:

Maybe you're right there... "completely protected mechanically" is a
rather vague phrase I keep seeing in the relevant documentation on
this topic, as being one of the criteria for deciding the size of
cable to use. I took it to mean that the earth cable was hidden from
sight/possible damage - mine is inside stud partitions or under
floorboards along its whole length, rather than being attached to
skirting boards(!) or whatever.

I thought that would be the case, it's not mechanically protected
then. Mechanically protected would mean it was enclosed in conduit or
trunking throught its entire length, including its passage through
walls and the like. That's something else you've learnt today! ;-)

Doesn't "mechanically protected" in the context of earth bonding mean
simply that it's not bare wire? On the other hand maybe that's just
"pretected against corrosion", on looking at my OSG it's not at all
clear what is meant by either of these terms.

Can anyone give a definitive meaning of "mechanically protected" and
"protected against corrosion" when applied to earth bonding wires?

--
Chris Green

wrote in message ...
Lurch wrote:
On 25 May 2004 23:49:16 -0700,
(Lobster) strung together this:

Maybe you're right there... "completely protected mechanically" is a
rather vague phrase I keep seeing in the relevant documentation on
this topic, as being one of the criteria for deciding the size of
cable to use. I took it to mean that the earth cable was hidden from
sight/possible damage - mine is inside stud partitions or under
floorboards along its whole length, rather than being attached to
skirting boards(!) or whatever.

I thought that would be the case, it's not mechanically protected
then. Mechanically protected would mean it was enclosed in conduit or
trunking throught its entire length, including its passage through
walls and the like. That's something else you've learnt today! ;-)

Doesn't "mechanically protected" in the context of earth bonding mean
simply that it's not bare wire? On the other hand maybe that's just
"pretected against corrosion", on looking at my OSG it's not at all
clear what is meant by either of these terms.

Can anyone give a definitive meaning of "mechanically protected" and
"protected against corrosion" when applied to earth bonding wires?

Chris Green


"Mechanically Protected" is sheathed within a covering that does not yield
easily to applied pressure or striking.

"Protected from corrosion" is where the system is not allowed to come into
contact with dampness or chemical ingress that may cause the conductors or its
insulation to breakdown and weaken it properties of doing its job properly.

"Lurch" wrote in message ...

Fair point, however it is 'most likely'' that 10mm will suffice. I
doubt anyone at wherever it is that the OP rings will have a clue
what he's on about anyway!

Yes, that occurred to me - getting through to someone that can answer
technical questions ain't easy.

Hmmm, you can, I'll stick to 10mm thanks! I can't see someone
rewiring there own house buying 100m of 16mm earth to use 3m of it
though!

A 50m reel isn't particularly expensive though, and you'll probably need
more than 3m to get to the water and gas pipes...

--
Andy

Z wrote:
In article , BigWallop
writes

"Lobster" wrote in message
om...
Hi

Just completing a house wiring job, I've now got myself a tad confused
about what size of earth cable I should be using to bond the incoming
gas and water pipes to the main earth near the electric meter. I've
already used 10mm, but have got myself worried that this isn't big
enough and would rather get it right now than have the inspector tell
me to change it later (it's not a trivial task, as the gas and
electric meters are at opposite ends of the house!)

The electricity installation is new (and not yet connected to the CU),
and it's PME. The earth cable is completely protected mechanically
along its length... is there any other info needed to assess the
correct earth size? Or do I need to ask the supply company, ahich is
what the stuff at www.tlc-direct.co.uk seems to be suggesting?

Many thanks
David

From the mains service head you need to run 10 mm csa' green/yellow sheathed
conductors. On all the other supplementary bonding you would use 6 mm csa'
green/yellow sheathed conductors.


Though if you have a drum of 10 use 10 save ending up with 2 half drums

Yeah, why not. Very good point.


---
http://www.basecuritysystems.no-ip.com

Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.691 / Virus Database: 452 - Release Date: 26/05/04