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UK diy (uk.d-i-y) For the discussion of all topics related to diy (do-it-yourself) in the UK. All levels of experience and proficency are welcome to join in to ask questions or offer solutions. |
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#1
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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. |
#2
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TN-S Earth clamp
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#3
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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. |
#5
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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. |
#6
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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 |
#7
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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) |
#8
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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.... |
#9
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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 :-) |
#10
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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 |
#11
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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 |
#12
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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! |
#13
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TN-S Earth clamp
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#14
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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 |
#15
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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 |
#16
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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 |
#17
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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. |
#18
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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 |
#19
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TN-S Earth clamp
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#20
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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 |
#21
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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 |
#22
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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 |
#23
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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 |
#24
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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 |
#25
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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. |
#26
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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 |
#27
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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 |
#28
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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. |
#29
Posted to uk.d-i-y
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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 |
#30
Posted to uk.d-i-y
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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 |
#31
Posted to uk.d-i-y
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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 |
#32
Posted to uk.d-i-y
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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 |
#33
Posted to uk.d-i-y
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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 |
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