TN-S Earth clamp
 

Had a proper look at the earthing on the new place today. The supply earth is provided by a clamp onto the sheath. It's not, so far as I can, a tightenable clamp.

https://www.flickr.com/photos/383551...posted-public/

It has a 10mm cable in which looks like it only just fits, can't see how I'd get a 16 in there. (tails are - at the moment - 25mm as far as a Henley, then down to 16mm)

I noticed that the clamp rotates freely around the sheath. Is that to be expected? I will get round to measuring the earth soon when the replacement test lead turns up.

TN-S Earth clamp
 

TN-S Earth clamp
 

On Sunday, 24 May 2020 21:03:22 UTC+1, Andy Burns wrote:
wrote:

It has a 10mm cable in which looks like it only just fits, can't see how I'd get a 16 in there.

Crimp a ring terminal on the cable? Depends what size ratchet crimp
you've got/can borrow?

Thanks!. Why didn't I think of that.

My crimper stops at 10mm, but I'm sure I can find someone with a 16.

TN-S Earth clamp
 

On 24/05/2020 20:49, wrote:
Had a proper look at the earthing on the new place today. The supply earth is provided by a clamp onto the sheath. It's not, so far as I can, a tightenable clamp.

https://www.flickr.com/photos/383551...posted-public/

It has a 10mm cable in which looks like it only just fits, can't see how I'd get a 16 in there. (tails are - at the moment - 25mm as far as a Henley, then down to 16mm)

I noticed that the clamp rotates freely around the sheath. Is that to be expected? I will get round to measuring the earth soon when the replacement test lead turns up.



FWLIW I think I'd ask if a "proper" PME can be supplied

https://www.ukpowernetworks.co.uk/electricity/earthing



--
Robin
reply-to address is (intended to be) valid

TN-S Earth clamp
 

On Sunday, 24 May 2020 21:44:45 UTC+1, Robin wrote:
On 24/05/2020 20:49, wrote:
Had a proper look at the earthing on the new place today. The supply earth is provided by a clamp onto the sheath. It's not, so far as I can, a tightenable clamp.

https://www.flickr.com/photos/383551...posted-public/

It has a 10mm cable in which looks like it only just fits, can't see how I'd get a 16 in there. (tails are - at the moment - 25mm as far as a Henley, then down to 16mm)

I noticed that the clamp rotates freely around the sheath. Is that to be expected? I will get round to measuring the earth soon when the replacement test lead turns up.



FWLIW I think I'd ask if a "proper" PME can be supplied

https://www.ukpowernetworks.co.uk/electricity/earthing

I was considering that. Assuming the clamp isn't expected to move as it does (??) I was going to call up and express concern about it, and see if that ended up with a PME conversion.

TN-S Earth clamp
 

On 24/05/2020 22:31, wrote:
On Sunday, 24 May 2020 21:44:45 UTC+1, Robin wrote:
On 24/05/2020 20:49, wrote:
Had a proper look at the earthing on the new place today. The supply earth is provided by a clamp onto the sheath. It's not, so far as I can, a tightenable clamp.

https://www.flickr.com/photos/383551...posted-public/

It has a 10mm cable in which looks like it only just fits, can't see how I'd get a 16 in there. (tails are - at the moment - 25mm as far as a Henley, then down to 16mm)

I noticed that the clamp rotates freely around the sheath. Is that to be expected? I will get round to measuring the earth soon when the replacement test lead turns up.



FWLIW I think I'd ask if a "proper" PME can be supplied

https://www.ukpowernetworks.co.uk/electricity/earthing

I was considering that. Assuming the clamp isn't expected to move as it does (??) I was going to call up and express concern about it, and see if that ended up with a PME conversion.

I was leaving the clamp to my youngers and betters :) But FWIW (a) a
clamp that moves patently means your Ze can change randomly, (b) clamps
(even constant force clamps) on lead sheathing are now a no-no, and (c)
I think tightening a clamp is for the brave and courageous.

*--
Robin
reply-to address is (intended to be) valid

TN-S Earth clamp
 

On 24/05/2020 20:49, wrote:
Had a proper look at the earthing on the new place today. The supply earth is provided by a clamp onto the sheath. It's not, so far as I can, a tightenable clamp.

https://www.flickr.com/photos/383551...posted-public/

It has a 10mm cable in which looks like it only just fits, can't see how I'd get a 16 in there. (tails are - at the moment - 25mm as far as a Henley, then down to 16mm)

I noticed that the clamp rotates freely around the sheath. Is that to be expected? I will get round to measuring the earth soon when the replacement test lead turns up.


No, the clamp should not move and will be an ineffective earth connection.

Report it to your DNO and they should either rectify it or provide PME.
(this may be delayed due to Coronovirus Regs)

TN-S Earth clamp
 

On Monday, 25 May 2020 09:44:10 UTC+1, Jack Harry Teesdale wrote:
On 24/05/2020 20:49, wrote:
Had a proper look at the earthing on the new place today. The supply earth is provided by a clamp onto the sheath. It's not, so far as I can, a tightenable clamp.

https://www.flickr.com/photos/383551...posted-public/

It has a 10mm cable in which looks like it only just fits, can't see how I'd get a 16 in there. (tails are - at the moment - 25mm as far as a Henley, then down to 16mm)

I noticed that the clamp rotates freely around the sheath. Is that to be expected? I will get round to measuring the earth soon when the replacement test lead turns up.


No, the clamp should not move and will be an ineffective earth connection..

Report it to your DNO and they should either rectify it or provide PME.
(this may be delayed due to Coronovirus Regs)

Thanks. That's what I thought, but nice to have it confirmed.

I rang up UK power and they were somewhat unhelpful, and want to know what Ze is before they will do anything (I tried arguing that what it is NOW is irrelevant, and I don't want to start waggling their clamp to demonstrate that it will change). Well, gives me something to do. I will call back and hope I get someone more helpful.

There's a lead water main. Turns out it does have its uses....

TN-S Earth clamp
 

On Mon, 25 May 2020 01:59:14 -0700 (PDT),
wrote:

On Monday, 25 May 2020 09:44:10 UTC+1, Jack Harry Teesdale wrote:
On 24/05/2020 20:49, wrote:
Had a proper look at the earthing on the new place today. The supply earth is provided by a clamp onto the sheath. It's not, so far as I can, a tightenable clamp.

https://www.flickr.com/photos/383551...posted-public/

It has a 10mm cable in which looks like it only just fits, can't see how I'd get a 16 in there. (tails are - at the moment - 25mm as far as a Henley, then down to 16mm)

I noticed that the clamp rotates freely around the sheath. Is that to be expected? I will get round to measuring the earth soon when the replacement test lead turns up.


No, the clamp should not move and will be an ineffective earth connection.

Report it to your DNO and they should either rectify it or provide PME.
(this may be delayed due to Coronovirus Regs)

Thanks. That's what I thought, but nice to have it confirmed.

I rang up UK power and they were somewhat unhelpful, and want to know what Ze is before they will do anything (I tried arguing that what it is NOW is irrelevant, and I don't want to start waggling their clamp to demonstrate that it will change). Well, gives me something to do. I will call back and hope I get someone more helpful.

You would always give them an 'estimated' figure :-)

TN-S Earth clamp
 

On Monday, 25 May 2020 09:59:17 UTC+1, wrote:
On Monday, 25 May 2020 09:44:10 UTC+1, Jack Harry Teesdale wrote:
On 24/05/2020 20:49, wrote:

Had a proper look at the earthing on the new place today. The supply earth is provided by a clamp onto the sheath. It's not, so far as I can, a tightenable clamp.

https://www.flickr.com/photos/383551...posted-public/

It has a 10mm cable in which looks like it only just fits, can't see how I'd get a 16 in there. (tails are - at the moment - 25mm as far as a Henley, then down to 16mm)

I noticed that the clamp rotates freely around the sheath. Is that to be expected? I will get round to measuring the earth soon when the replacement test lead turns up.


No, the clamp should not move and will be an ineffective earth connection.

Report it to your DNO and they should either rectify it or provide PME.
(this may be delayed due to Coronovirus Regs)

Thanks. That's what I thought, but nice to have it confirmed.

I rang up UK power and they were somewhat unhelpful, and want to know what Ze is before they will do anything (I tried arguing that what it is NOW is irrelevant, and I don't want to start waggling their clamp to demonstrate that it will change). Well, gives me something to do. I will call back and hope I get someone more helpful.

There's a lead water main. Turns out it does have its uses....

If you're 100% RCDed it's not ideal, but not an immediate threat to life. If you're not RCDed it is.

Be aware that they will only reconnect your supply after the work if your water & gas/oil are bonded.


NT

TN-S Earth clamp
 

On 25/05/2020 11:48, wrote:
On Monday, 25 May 2020 09:59:17 UTC+1, wrote:
On Monday, 25 May 2020 09:44:10 UTC+1, Jack Harry Teesdale wrote:
On 24/05/2020 20:49, wrote:

Had a proper look at the earthing on the new place today. The supply earth is provided by a clamp onto the sheath. It's not, so far as I can, a tightenable clamp.

https://www.flickr.com/photos/383551...posted-public/

It has a 10mm cable in which looks like it only just fits, can't see how I'd get a 16 in there. (tails are - at the moment - 25mm as far as a Henley, then down to 16mm)

I noticed that the clamp rotates freely around the sheath. Is that to be expected? I will get round to measuring the earth soon when the replacement test lead turns up.


No, the clamp should not move and will be an ineffective earth connection.

Report it to your DNO and they should either rectify it or provide PME.
(this may be delayed due to Coronovirus Regs)

Thanks. That's what I thought, but nice to have it confirmed.

I rang up UK power and they were somewhat unhelpful, and want to know what Ze is before they will do anything (I tried arguing that what it is NOW is irrelevant, and I don't want to start waggling their clamp to demonstrate that it will change). Well, gives me something to do. I will call back and hope I get someone more helpful.

There's a lead water main. Turns out it does have its uses....

If you're 100% RCDed it's not ideal, but not an immediate threat to life. If you're not RCDed it is.

Be aware that they will only reconnect your supply after the work if your water & gas/oil are bonded.



and IIRC to current (continuous 10mm) standard

--
Robin
reply-to address is (intended to be) valid

TN-S Earth clamp
 

On Monday, 25 May 2020 13:13:32 UTC+1, Robin wrote:
On 25/05/2020 11:48, wrote:

Be aware that they will only reconnect your supply after the work if your water & gas/oil are bonded.



and IIRC to current (continuous 10mm) standard

Sorting out the bonding mess was how I noticed the problem in the first place!

TN-S Earth clamp
 

On 25/05/2020 11:48, wrote:


Be aware that they will only reconnect your supply after the work if your water & gas/oil are bonded.



More likely they will not commence work if they are not bonded.


--
Adam

TN-S Earth clamp
 

On 25/05/2020 13:42, wrote:
On Monday, 25 May 2020 13:13:32 UTC+1, Robin wrote:
On 25/05/2020 11:48, wrote:

Be aware that they will only reconnect your supply after the work if your water & gas/oil are bonded.



and IIRC to current (continuous 10mm) standard

Sorting out the bonding mess was how I noticed the problem in the first place!



Assuming that the electric co are not complete dickheads then they will
probably install an isolator and earth block but not actually connect
back up your power or the earth.

It's a 15 minute DIY job that does not require an electrician just a
flat screwdriver, allen keys and snips (or Stanley knife if you prefer)
to connect into these [1]

If you do need to cut any meter seals I have loads of NE ones available.

I doubt they will PME it. I suspect they will jut fit a series 6 cutout
and keep it as a TN-S.

https://www.wt-henley.com/pdf/14688_...cut_outs_2.pdf


[1] Not allowing for the 30 minutes to find the Allen keys that you put
somewhere safe the last time you used them:-)
--
Adam

TN-S Earth clamp
 

On 25/05/2020 10:21, Scott wrote:
On Mon, 25 May 2020 01:59:14 -0700 (PDT),
wrote:

On Monday, 25 May 2020 09:44:10 UTC+1, Jack Harry Teesdale wrote:
On 24/05/2020 20:49, wrote:
Had a proper look at the earthing on the new place today. The supply earth is provided by a clamp onto the sheath. It's not, so far as I can, a tightenable clamp.

https://www.flickr.com/photos/383551...posted-public/

It has a 10mm cable in which looks like it only just fits, can't see how I'd get a 16 in there. (tails are - at the moment - 25mm as far as a Henley, then down to 16mm)

I noticed that the clamp rotates freely around the sheath. Is that to be expected? I will get round to measuring the earth soon when the replacement test lead turns up.


No, the clamp should not move and will be an ineffective earth connection.

Report it to your DNO and they should either rectify it or provide PME.
(this may be delayed due to Coronovirus Regs)

Thanks. That's what I thought, but nice to have it confirmed.

I rang up UK power and they were somewhat unhelpful, and want to know what Ze is before they will do anything (I tried arguing that what it is NOW is irrelevant, and I don't want to start waggling their clamp to demonstrate that it will change). Well, gives me something to do. I will call back and hope I get someone more helpful.

You would always give them an 'estimated' figure :-)



Especially after slackening the earth clamp off.

Couple of ohms should do it.

I like your thinking.

--
Adam

TN-S Earth clamp
 

Robin wrote:

On 25/05/2020 11:48, wrote:
On Monday, 25 May 2020 09:59:17 UTC+1, wrote:
On Monday, 25 May 2020 09:44:10 UTC+1, Jack Harry Teesdale wrote: On
24/05/2020 20:49, wrote:

Had a proper look at the earthing on the new place today. The supply
earth is provided by a clamp onto the sheath. It's not, so far as I
can, a tightenable clamp.
https://www.flickr.com/photos/383551.../dateposted-pu
blic/ It has a 10mm cable in which looks like it only just fits,
can't see how I'd get a 16 in there. (tails are - at the moment - 25mm
as far as a Henley, then down to 16mm) I noticed that the clamp
rotates freely around the sheath. Is that to be expected? I will get
round to measuring the earth soon when the replacement test lead turns
up. No, the clamp should not move and will be an ineffective earth
connection.

Report it to your DNO and they should either rectify it or provide
PME. (this may be delayed due to Coronovirus Regs)

Thanks. That's what I thought, but nice to have it confirmed.

I rang up UK power and they were somewhat unhelpful, and want to know
what Ze is before they will do anything (I tried arguing that what it is
NOW is irrelevant, and I don't want to start waggling their clamp to
demonstrate that it will change). Well, gives me something to do. I
will call back and hope I get someone more helpful.

There's a lead water main. Turns out it does have its uses....

If you're 100% RCDed it's not ideal, but not an immediate threat to
life. If you're not RCDed it is.

Be aware that they will only reconnect your supply after the work if
your water & gas/oil are bonded.



and IIRC to current (continuous 10mm) standard

What does 'continuous' mean in this context? Surely it doesn't mean no
joints? Or does it means no thinner sections?

--

Roger Hayter

TN-S Earth clamp
 

Be aware that they will only reconnect your supply after the work if
your water & gas/oil are bonded.



and IIRC to current (continuous 10mm) standard

What does 'continuous' mean in this context? Surely it doesn't mean no
joints? Or does it means no thinner sections?


It means if your water bond is on the way to the gas, so you do it all in one length, make sure it is one length(not cut). That way if someone disconnects the water bond, gas is still bonded.

I think I learned that here, but I've seen it referenced elsewhere too.

TN-S Earth clamp
 

wrote:

Be aware that they will only reconnect your supply after the work if
your water & gas/oil are bonded.



and IIRC to current (continuous 10mm) standard

What does 'continuous' mean in this context? Surely it doesn't mean no
joints? Or does it means no thinner sections?


It means if your water bond is on the way to the gas, so you do it all in
one length, make sure it is one length(not cut). That way if someone
disconnects the water bond, gas is still bonded.

I think I learned that here, but I've seen it referenced elsewhere too.

But a terminal block fixed to the wall with separate wires to gas and
water would be ok? Depends on the precise layout which is ieasier.

--

Roger Hayter

TN-S Earth clamp
 

On 26/05/2020 12:59, wrote:

Be aware that they will only reconnect your supply after the work if
your water & gas/oil are bonded.



and IIRC to current (continuous 10mm) standard

What does 'continuous' mean in this context? Surely it doesn't mean no
joints? Or does it means no thinner sections?

It means if your water bond is on the way to the gas, so you do it all in one length, make sure it is one length(not cut). That way if someone disconnects the water bond, gas is still bonded.

I think I learned that here, but I've seen it referenced elsewhere too.


Yes - sorry I was misleadingly vague.

AIUI it's not mandatory part of BS7671 but something that BS7430 and
Guidance Note 8 says "should" be done - and makes for a quieter life.

And while there's no regulation against joints in main bonding with
junction boxes (or chock strip) suitably labelled I'd extend with an
uninsulated crimp.

PS

Sorry too that for some reason I thought I knew UKPN was your DNO.

--
Robin
reply-to address is (intended to be) valid

TN-S Earth clamp
 

On 26/05/2020 13:32, Roger Hayter wrote:
wrote:

Be aware that they will only reconnect your supply after the work if
your water & gas/oil are bonded.



and IIRC to current (continuous 10mm) standard

What does 'continuous' mean in this context? Surely it doesn't mean no
joints? Or does it means no thinner sections?


It means if your water bond is on the way to the gas, so you do it all in
one length, make sure it is one length(not cut). That way if someone
disconnects the water bond, gas is still bonded.

I think I learned that here, but I've seen it referenced elsewhere too.

But a terminal block fixed to the wall with separate wires to gas and
water would be ok? Depends on the precise layout which is ieasier.


Call it an earth marshalled busbar terminal and all is fine.

--
Adam

TN-S Earth clamp
 

Robin wrote:

On 26/05/2020 12:59, wrote:

Be aware that they will only reconnect your supply after the work if
your water & gas/oil are bonded.



and IIRC to current (continuous 10mm) standard

What does 'continuous' mean in this context? Surely it doesn't mean no
joints? Or does it means no thinner sections?

It means if your water bond is on the way to the gas, so you do it all
in one length, make sure it is one length(not cut). That way if someone
disconnects the water bond, gas is still bonded.

I think I learned that here, but I've seen it referenced elsewhere too.


Yes - sorry I was misleadingly vague.

AIUI it's not mandatory part of BS7671 but something that BS7430 and
Guidance Note 8 says "should" be done - and makes for a quieter life.

And while there's no regulation against joints in main bonding with
junction boxes (or chock strip) suitably labelled I'd extend with an
uninsulated crimp.

PS

Sorry too that for some reason I thought I knew UKPN was your DNO.
You mean if you fix a 2" X 3/4' chunk of brass on the wall with several
green and yellow wires going into it you would have to label it "safety
electral earth etc"? And should you enclose it to discourage
interference?

Yes it makes sense, though my electrican did not bother. Maybe he (or
I) might have done if it hadn't been in a workshop.

--

Roger Hayter

TN-S Earth clamp
 

On 27/05/2020 13:51, Roger Hayter wrote:
Robin wrote:

On 26/05/2020 12:59, wrote:

Be aware that they will only reconnect your supply after the work if
your water & gas/oil are bonded.



and IIRC to current (continuous 10mm) standard

What does 'continuous' mean in this context? Surely it doesn't mean no
joints? Or does it means no thinner sections?

It means if your water bond is on the way to the gas, so you do it all
in one length, make sure it is one length(not cut). That way if someone
disconnects the water bond, gas is still bonded.

I think I learned that here, but I've seen it referenced elsewhere too.


Yes - sorry I was misleadingly vague.

AIUI it's not mandatory part of BS7671 but something that BS7430 and
Guidance Note 8 says "should" be done - and makes for a quieter life.

And while there's no regulation against joints in main bonding with
junction boxes (or chock strip) suitably labelled I'd extend with an
uninsulated crimp.

PS

Sorry too that for some reason I thought I knew UKPN was your DNO.
You mean if you fix a 2" X 3/4' chunk of brass on the wall with several
green and yellow wires going into it you would have to label it "safety
electral earth etc"? And should you enclose it to discourage
interference?

Yes it makes sense, though my electrican did not bother. Maybe he (or
I) might have done if it hadn't been in a workshop.


All I meant was that I agree with those who argue a screwed connection
in a main bonding conductor brings it within 514.13.1((ii) ("a point of
connection of every bonding conductor to an extraneous-conductive-part")
and so requires the warning notice. It can be argued the other way but
I was persuaded by the fact that the join must be accessible (else you
wouldn't use a screwed connection, would you?) so it makes sense to
require a warning notice there as at connections to pipes etc.

What happens in practice is of course another matter. But I've seen
labels used where the bonding used a combination of cable and pipe.

I don't know just what your chunk of brass was for but 514.13.1((iii)
provides that no label is needed for a MET by switchgear.


--
Robin
reply-to address is (intended to be) valid

TN-S Earth clamp
 

On 27/05/2020 16:11, Robin wrote:
On 27/05/2020 13:51, Roger Hayter wrote:
Robin wrote:

On 26/05/2020 12:59, wrote:

Be aware that they will only reconnect your supply after the work if
your water & gas/oil are bonded.



and IIRC to current (continuous 10mm) standard

What does 'continuous' mean in this context?Â* Surely it doesn't
mean no
joints?Â*Â* Or does it means no thinner sections?

It means if your water bond is on the way to the gas, so you do it all
in one length, make sure it is one length(not cut). That way if someone
disconnects the water bond, gas is still bonded.

I think I learned that here, but I've seen it referenced elsewhere too.


Yes - sorry I was misleadingly vague.

AIUI it's not mandatory part of BS7671 but something that BS7430 and
Guidance Note 8 says "should" be done - and makes for a quieter life.

And while there's no regulation against joints in main bonding with
junction boxes (or chock strip) suitably labelled I'd extend with an
uninsulated crimp.

PS

Sorry too that for some reason I thought I knew UKPN was your DNO.
You mean if you fix a 2" X 3/4' chunk of brass on the wall with several
green and yellow wires going into it you would have to label it "safety
electral earth etc"?Â*Â* And should you enclose it to discourage
interference?

Yes it makes sense, though my electrican did not bother.Â*Â* Maybe he (or
I) might have done if it hadn't been in a workshop.


All I meant was that I agree with those who argue a screwed connection
in a main bonding conductor brings it within 514.13.1((ii) ("a point of
connection of every bonding conductor to an extraneous-conductive-part")
and so requires the warning notice.Â* It can be argued the other way but
I was persuaded by the fact that the join must be accessible (else you
wouldn't use a screwed connection, would you?) so it makes sense to
require a warning notice there as at connections to pipes etc.

What happens in practice is of course another matter.Â* But I've seen
labels used where the bonding used a combination of cable and pipe.

I don't know just what your chunk of brass was for but 514.13.1((iii)
provides that no label is needed for a MET by switchgear.



Just call it an earth marshalling bar?

Stickers that say "earth warning do not remove" are cheap



--
Adam

TN-S Earth clamp
 

On 27/05/2020 20:14, ARW wrote:
On 27/05/2020 16:11, Robin wrote:
On 27/05/2020 13:51, Roger Hayter wrote:
snip

Sorry too that for some reason I thought I knew UKPN was your DNO.
You mean if you fix a 2" X 3/4' chunk of brass on the wall with several
green and yellow wires going into it you would have to label it "safety
electral earth etc"?Â*Â* And should you enclose it to discourage
interference?

Yes it makes sense, though my electrican did not bother.Â*Â* Maybe he (or
I) might have done if it hadn't been in a workshop.


All I meant was that I agree with those who argue a screwed connection
in a main bonding conductor brings it within 514.13.1((ii) ("a point
of connection of every bonding conductor to an
extraneous-conductive-part") and so requires the warning notice.Â* It
can be argued the other way but I was persuaded by the fact that the
join must be accessible (else you wouldn't use a screwed connection,
would you?) so it makes sense to require a warning notice there as at
connections to pipes etc.

What happens in practice is of course another matter.Â* But I've seen
labels used where the bonding used a combination of cable and pipe.

I don't know just what your chunk of brass was for but 514.13.1((iii)
provides that no label is needed for a MET by switchgear.



Just call it an earth marshalling bar?

Stickers that say "earth warning do not remove" are cheap



I'll be guided by you!

I've seen those labels on EMBs a few times (once inside a CU) but never
really understood why they are used instead of BS 951 labels or how they
finesse 514.13.1.


--
Robin
reply-to address is (intended to be) valid

TN-S Earth clamp
 

In article ,
wrote:
Had a proper look at the earthing on the new place today. The supply earth is provided by a clamp onto the sheath. It's not, so far as I can, a tightenable clamp.


That sounds like what existed here on an old installation. Where the
incoming lead water main and the sheath to the mains riser provided the
rudimentary earth.

If you can use the mains riser for earth it needs the correct clamp - but
that's really a job for the supply company to make sure it is up to it.

--
*How much deeper would the oceans be without sponges? *

Dave Plowman London SW
To e-mail, change noise into sound.

TN-S Earth clamp
 

In article ,
Dave Plowman (News) wrote:
In article ,
wrote:
Had a proper look at the earthing on the new place today. The supply
earth is provided by a clamp onto the sheath. It's not, so far as I
can, a tightenable clamp.


That sounds like what existed here on an old installation. Where the
incoming lead water main and the sheath to the mains riser provided the
rudimentary earth.

If you can use the mains riser for earth it needs the correct clamp - but
that's really a job for the supply company to make sure it is up to it.

The electrical installaton here, probably 1920s, got its earth from the
incoming cable sheath. However, after a few days of being fed from a
generator, tests on reconnection showed an inadequate earth from that cable
sheath. The supply company changed things to PME.

--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle

TN-S Earth clamp
 

On 27/05/2020 21:44, Robin wrote:
On 27/05/2020 20:14, ARW wrote:
On 27/05/2020 16:11, Robin wrote:
On 27/05/2020 13:51, Roger Hayter wrote:
snip

Sorry too that for some reason I thought I knew UKPN was your DNO.
You mean if you fix a 2" X 3/4' chunk of brass on the wall with several
green and yellow wires going into it you would have to label it "safety
electral earth etc"?Â*Â* And should you enclose it to discourage
interference?

Yes it makes sense, though my electrican did not bother.Â*Â* Maybe he (or
I) might have done if it hadn't been in a workshop.


All I meant was that I agree with those who argue a screwed
connection in a main bonding conductor brings it within 514.13.1((ii)
("a point of connection of every bonding conductor to an
extraneous-conductive-part") and so requires the warning notice.Â* It
can be argued the other way but I was persuaded by the fact that the
join must be accessible (else you wouldn't use a screwed connection,
would you?) so it makes sense to require a warning notice there as at
connections to pipes etc.

What happens in practice is of course another matter.Â* But I've seen
labels used where the bonding used a combination of cable and pipe.

I don't know just what your chunk of brass was for but 514.13.1((iii)
provides that no label is needed for a MET by switchgear.



Just call it an earth marshalling bar?

Stickers that say "earth warning do not remove" are cheap



I'll be guided by you!

I've seen those labels on EMBs a few times (once inside a CU) but never
really understood why they are used instead of BS 951 labels or how they
finesse 514.13.1.



Personally I do not think it matters that much.

But some people like to see safety stickers and they get paid to look
for non problems.

--
Adam

TN-S Earth clamp
 

On Monday, 25 May 2020 09:59:17 UTC+1, wrote:
On Monday, 25 May 2020 09:44:10 UTC+1, Jack Harry Teesdale wrote:
On 24/05/2020 20:49, wrote:
Had a proper look at the earthing on the new place today. The supply earth is provided by a clamp onto the sheath. It's not, so far as I can, a tightenable clamp.

https://www.flickr.com/photos/383551...posted-public/

It has a 10mm cable in which looks like it only just fits, can't see how I'd get a 16 in there. (tails are - at the moment - 25mm as far as a Henley, then down to 16mm)

I noticed that the clamp rotates freely around the sheath. Is that to be expected? I will get round to measuring the earth soon when the replacement test lead turns up.


No, the clamp should not move and will be an ineffective earth connection.

Report it to your DNO and they should either rectify it or provide PME.
(this may be delayed due to Coronovirus Regs)

Thanks. That's what I thought, but nice to have it confirmed.

I rang up UK power and they were somewhat unhelpful, and want to know what Ze is before they will do anything (I tried arguing that what it is NOW is irrelevant, and I don't want to start waggling their clamp to demonstrate that it will change). Well, gives me something to do. I will call back and hope I get someone more helpful.

There's a lead water main. Turns out it does have its uses....

Leads finally turned up. Ze is 0.2. I moved their clamp gently, and established that it's a) stiffer than I remembered from Monday, and b) didn't affect the measurement. BTW it's not a 951 clamp.

TN-S Earth clamp
 

On 28/05/2020 18:26, ARW wrote:
On 27/05/2020 21:44, Robin wrote:
On 27/05/2020 20:14, ARW wrote:
On 27/05/2020 16:11, Robin wrote:
On 27/05/2020 13:51, Roger Hayter wrote:
snip

Sorry too that for some reason I thought I knew UKPN was your DNO.
You mean if you fix a 2" X 3/4' chunk of brass on the wall with
several
green and yellow wires going into it you would have to label it
"safety
electral earth etc"?Â*Â* And should you enclose it to discourage
interference?

Yes it makes sense, though my electrican did not bother.Â*Â* Maybe he
(or
I) might have done if it hadn't been in a workshop.


All I meant was that I agree with those who argue a screwed
connection in a main bonding conductor brings it within
514.13.1((ii) ("a point of connection of every bonding conductor to
an extraneous-conductive-part") and so requires the warning notice.
It can be argued the other way but I was persuaded by the fact that
the join must be accessible (else you wouldn't use a screwed
connection, would you?) so it makes sense to require a warning
notice there as at connections to pipes etc.

What happens in practice is of course another matter.Â* But I've seen
labels used where the bonding used a combination of cable and pipe.

I don't know just what your chunk of brass was for but
514.13.1((iii) provides that no label is needed for a MET by
switchgear.



Just call it an earth marshalling bar?

Stickers that say "earth warning do not remove" are cheap



I'll be guided by you!

I've seen those labels on EMBs a few times (once inside a CU) but
never really understood why they are used instead of BS 951 labels or
how they finesse 514.13.1.



Personally I do not think it matters that much.

But some people like to see safety stickers and they get paid to look
for non problems.


Fair point. I'll put me clipboard away.

--
Robin
reply-to address is (intended to be) valid

TN-S Earth clamp
 

Robin wrote:

On 27/05/2020 13:51, Roger Hayter wrote:
Robin wrote:

On 26/05/2020 12:59, wrote:

Be aware that they will only reconnect your supply after the work if
your water & gas/oil are bonded.



and IIRC to current (continuous 10mm) standard

What does 'continuous' mean in this context? Surely it doesn't mean no
joints? Or does it means no thinner sections?

It means if your water bond is on the way to the gas, so you do it all
in one length, make sure it is one length(not cut). That way if someone
disconnects the water bond, gas is still bonded.

I think I learned that here, but I've seen it referenced elsewhere too.


Yes - sorry I was misleadingly vague.

AIUI it's not mandatory part of BS7671 but something that BS7430 and
Guidance Note 8 says "should" be done - and makes for a quieter life.

And while there's no regulation against joints in main bonding with
junction boxes (or chock strip) suitably labelled I'd extend with an
uninsulated crimp.

PS

Sorry too that for some reason I thought I knew UKPN was your DNO.
You mean if you fix a 2" X 3/4' chunk of brass on the wall with several
green and yellow wires going into it you would have to label it "safety
electral earth etc"? And should you enclose it to discourage
interference?

Yes it makes sense, though my electrican did not bother. Maybe he (or
I) might have done if it hadn't been in a workshop.


All I meant was that I agree with those who argue a screwed connection
in a main bonding conductor brings it within 514.13.1((ii) ("a point of
connection of every bonding conductor to an extraneous-conductive-part")
and so requires the warning notice. It can be argued the other way but
I was persuaded by the fact that the join must be accessible (else you
wouldn't use a screwed connection, would you?) so it makes sense to
require a warning notice there as at connections to pipes etc.

What happens in practice is of course another matter. But I've seen
labels used where the bonding used a combination of cable and pipe.

I don't know just what your chunk of brass was for but 514.13.1((iii)
provides that no label is needed for a MET by switchgear.

It's slighly interesting. The person who wired my house originally
took equipotential bonding remarkably seriously and throughout the house
(at least in all rooms with any CH pipes or extraneous metal work which
I think was everywhere except the conservatory) he ran a network of
10mm insulated earth wire in parallel with every bit of the socket
wiring plus to every pipe, even ones connected by copper back to the
boiler. If I felt like burning the insulation off I'd have about 10kg
of copper I've ripped out doing other jobs. A consequence was an earth
terminal block in almost every room and the electrician used one of them
which was actually directly connected to the supply earth block, rather
than pulling a new wire in from the supply board to do the one bit of
bonding the original owner forgot, which was the oil feed into the house
- one of very few that was actually required. Though since it goes to
the outside oil tank with no earthing to speak of it therefore creates a
new PME hazard. In the context a label saying this connection is
actually wanted might be sensible, though it would have to say why in
the context of dozens of other pointless earth labels.



--

Roger Hayter

TN-S Earth clamp
 

On Friday, 29 May 2020 12:38:42 UTC+1, Roger Hayter wrote:
Robin wrote:

On 27/05/2020 13:51, Roger Hayter wrote:
Robin wrote:

On 26/05/2020 12:59, wrote:

Be aware that they will only reconnect your supply after the work if
your water & gas/oil are bonded.



and IIRC to current (continuous 10mm) standard

What does 'continuous' mean in this context? Surely it doesn't mean no
joints? Or does it means no thinner sections?

It means if your water bond is on the way to the gas, so you do it all
in one length, make sure it is one length(not cut). That way if someone
disconnects the water bond, gas is still bonded.

I think I learned that here, but I've seen it referenced elsewhere too.


Yes - sorry I was misleadingly vague.

AIUI it's not mandatory part of BS7671 but something that BS7430 and
Guidance Note 8 says "should" be done - and makes for a quieter life.

And while there's no regulation against joints in main bonding with
junction boxes (or chock strip) suitably labelled I'd extend with an
uninsulated crimp.

PS

Sorry too that for some reason I thought I knew UKPN was your DNO.
You mean if you fix a 2" X 3/4' chunk of brass on the wall with several
green and yellow wires going into it you would have to label it "safety
electral earth etc"? And should you enclose it to discourage
interference?

Yes it makes sense, though my electrican did not bother. Maybe he (or
I) might have done if it hadn't been in a workshop.


All I meant was that I agree with those who argue a screwed connection
in a main bonding conductor brings it within 514.13.1((ii) ("a point of
connection of every bonding conductor to an extraneous-conductive-part")
and so requires the warning notice. It can be argued the other way but
I was persuaded by the fact that the join must be accessible (else you
wouldn't use a screwed connection, would you?) so it makes sense to
require a warning notice there as at connections to pipes etc.

What happens in practice is of course another matter. But I've seen
labels used where the bonding used a combination of cable and pipe.

I don't know just what your chunk of brass was for but 514.13.1((iii)
provides that no label is needed for a MET by switchgear.

It's slighly interesting. The person who wired my house originally
took equipotential bonding remarkably seriously and throughout the house
(at least in all rooms with any CH pipes or extraneous metal work which
I think was everywhere except the conservatory) he ran a network of
10mm insulated earth wire in parallel with every bit of the socket
wiring plus to every pipe, even ones connected by copper back to the
boiler. If I felt like burning the insulation off I'd have about 10kg
of copper I've ripped out doing other jobs. A consequence was an earth
terminal block in almost every room and the electrician used one of them
which was actually directly connected to the supply earth block, rather
than pulling a new wire in from the supply board to do the one bit of
bonding the original owner forgot, which was the oil feed into the house
- one of very few that was actually required. Though since it goes to
the outside oil tank with no earthing to speak of it therefore creates a
new PME hazard. In the context a label saying this connection is
actually wanted might be sensible, though it would have to say why in
the context of dozens of other pointless earth labels.

When you've finally ripped it all out, then the regs will require equipotential bonding in all rooms.


NT

TN-S Earth clamp
 

On 29/05/2020 12:38, Roger Hayter wrote:
snip

It's slighly interesting. The person who wired my house originally
took equipotential bonding remarkably seriously and throughout the house
(at least in all rooms with any CH pipes or extraneous metal work which
I think was everywhere except the conservatory) he ran a network of
10mm insulated earth wire in parallel with every bit of the socket
wiring plus to every pipe, even ones connected by copper back to the
boiler. If I felt like burning the insulation off I'd have about 10kg
of copper I've ripped out doing other jobs. A consequence was an earth
terminal block in almost every room and the electrician used one of them
which was actually directly connected to the supply earth block, rather
than pulling a new wire in from the supply board to do the one bit of
bonding the original owner forgot, which was the oil feed into the house
- one of very few that was actually required. Though since it goes to
the outside oil tank with no earthing to speak of it therefore creates a
new PME hazard. In the context a label saying this connection is
actually wanted might be sensible, though it would have to say why in
the context of dozens of other pointless earth labels.



Others may know what was behind that. To me it sounds like someone (a)
installing high integrity earthing without understanding what was and
wasn't required or (b) with an awful lot of 10mm green/yellow single to
bill to an unsuspecting client. Any idea when it was done?

--
Robin
reply-to address is (intended to be) valid

TN-S Earth clamp
 

Robin wrote:

On 29/05/2020 12:38, Roger Hayter wrote:
snip

It's slighly interesting. The person who wired my house originally
took equipotential bonding remarkably seriously and throughout the house
(at least in all rooms with any CH pipes or extraneous metal work which
I think was everywhere except the conservatory) he ran a network of
10mm insulated earth wire in parallel with every bit of the socket
wiring plus to every pipe, even ones connected by copper back to the
boiler. If I felt like burning the insulation off I'd have about 10kg
of copper I've ripped out doing other jobs. A consequence was an earth
terminal block in almost every room and the electrician used one of them
which was actually directly connected to the supply earth block, rather
than pulling a new wire in from the supply board to do the one bit of
bonding the original owner forgot, which was the oil feed into the house
- one of very few that was actually required. Though since it goes to
the outside oil tank with no earthing to speak of it therefore creates a
new PME hazard. In the context a label saying this connection is
actually wanted might be sensible, though it would have to say why in
the context of dozens of other pointless earth labels.



Others may know what was behind that. To me it sounds like someone (a)
installing high integrity earthing without understanding what was and
wasn't required or (b) with an awful lot of 10mm green/yellow single to
bill to an unsuspecting client. Any idea when it was done?

About 40 years ago, by the householder. He had other wiring quirks.

--

Roger Hayter