This may seem very basic but after a recent discussion and differences of opinion just interested to here peoples views on tests required for replacing a power point.
I would assume tests only required for work as per ESC. Replaced/ maintained power point to original condition
- as3000
-Polarity
-ESR 73A
in the case of a low voltage installation or part installation, do all of the
following:
(i) ensure that the polarity and phase rotation of the supply are cor-
rect:
(ii) ensure that the protection of the supply is correctly rated:
(iii) ensure that the installation or part installation to be connected is
compatible with the supply system:
(iv) if the supply is from a MEN system, verify that there is a main
earthing system.
3l ELI test as this would veryfy the earthing system and also tells you correct polarity except neutral/ earth.
would you be expected to test polarity from msb to confirm neutral earth polarity. ( men link or fsc neutral removed)
Just not sure how responsible you are with replacing a power point in the situation where you have put the correct colours into the correct terminals but say the earth and neutral was transposed at msb from original install)
Iv never been in a maintenence role with this sort of work I'm used to doing full tests on new builds so just was wondering.
Thanks.
Replace power point testing
Re: Replace power point testing
You are correct that a 'part installation" can be as small as a single accessory;
and that re-connecting after disconnection for maintenance is still "connecting to supply".
So yes ESR 73A applies.
An argument can be made that ESR 73A is only intended to apply for new connections, and not to maintenance re-connections nor to reconnections after 6 months; but it's unconvincing.
Also that restoring to original condition is an acceptable option under ESR 59(3)
59(1) requires testing i.a.w "3000"; but that's for installation / alteration work; not for maintenance.
And the testing specified in "3000" is for when installation PRW has been carried out;
ESR 73A (1)(b) requires the person connecting (anything) to be satisfied that the testing required by "these regulations" has been carried out.
Since 59(1) doesn't apply; that just leaves 73A(1)(e).
(i) "polarity / phase rotation of the supply" cdan logically only refer to the supply to the part-installation being connected;
so for a socket outlet yes you need to test at the socket but you don't need to go upstream and prove correct polarity / rotation at incoming mains.
(ii) same to 'protection of supply" being correctly rated: check the protection of the subcircuit concerned.
(iii) same for compatibility with supply system. As a socket outlet, it will generally be in the TN-S part of the installation.
(iv) In almost every case (anything supplied from grid), supply is from an MEN system; which is TNC up to MEN link, and TN-S after that.
So yes, technically we have to confirm that there is a main earthing system any time we connect something.
The reason for this requirement is that there's a good chance that older installations, originally using a metal waterpipe as their earth electrode, may have had the plumbing upgraded - and in the process lost their electrode.
Which is a significant safety issue, as the safety of the entire MEN distribution system relies on each installation having an electrode.
Between them these electrodes keep the distribution N at close to earth potential.
So it actually makes sense that whenever maintenance is done; the existence of the man earthing system (defined as the MEN link, the MEC, and the electrode) should be confirmed.
And you can't do that with an EFLI test.
The EFL for a socket doesn't tell you anything useful about the main earthing system; because the only part of the system that's part of the EFL is the MEN link.
You should be finding the electrode, and the MEC at swbd, and testing that they are adequately connected together.
However I suspect this check is almost never done.
You are correct that no form of polarity test done at a socket using a "polarity tester" can detect a N-E reversal.
However there are other forms of polarity test that can do so. Refer to AS/NZS 3017.
For any fitting replacement (and especially for a socket); if N & E have been swapped, we should find it.
Just in case we didn't actually get those coloured wires in the right terminals.
Everyone makes mistakes; the point being to find them before they cause harm.
If we instead find someone else's earlier error, that's a bonus - we've left it safer than it was
We can't leave it once we've found it, because what matters is not what colour wire we put into which terminal,
but that the E terminal is connected to the E bar and the N terminal to the N bar.
Our work isn't correct unless we prove that;
so doesn't matter who made the mistake, nor when they made it.
A socket is a point that's required to be earthed, so obviously an earth continuity test is necessary.
And by testing that - with trailing lead , and either RCD off or MEN link removed for testing -
you also prove that the N & E haven't been swapped between you and the swbd the circuit originates at.
After that, you can test A(s) & N.
Do N after replacing the link; by measuring N-E at the socket.
(A standard live polarity test can't always show the difference between link in & link out)
Then an EFLI test, if there's no RCD.
Again the EC test will have given you half the info, ie the resistance of the PEC,
so the full EFLI test just confirms that the actives are also low enough impedance for (fault) protection to operate correctly - [73A(e)(ii)]
And note that since there is a supply available, you have to use the 'live" test method.
We're generally only responsible for what we do, not for what happened before.
ESR 13(1)states clearly the extent of our responsibility:
(a) do what you do correctly; and
(b) don't make anything else less safe than it was.
and that re-connecting after disconnection for maintenance is still "connecting to supply".
So yes ESR 73A applies.
An argument can be made that ESR 73A is only intended to apply for new connections, and not to maintenance re-connections nor to reconnections after 6 months; but it's unconvincing.
Also that restoring to original condition is an acceptable option under ESR 59(3)
59(1) requires testing i.a.w "3000"; but that's for installation / alteration work; not for maintenance.
And the testing specified in "3000" is for when installation PRW has been carried out;
ESR 73A (1)(b) requires the person connecting (anything) to be satisfied that the testing required by "these regulations" has been carried out.
Since 59(1) doesn't apply; that just leaves 73A(1)(e).
(i) "polarity / phase rotation of the supply" cdan logically only refer to the supply to the part-installation being connected;
so for a socket outlet yes you need to test at the socket but you don't need to go upstream and prove correct polarity / rotation at incoming mains.
(ii) same to 'protection of supply" being correctly rated: check the protection of the subcircuit concerned.
(iii) same for compatibility with supply system. As a socket outlet, it will generally be in the TN-S part of the installation.
(iv) In almost every case (anything supplied from grid), supply is from an MEN system; which is TNC up to MEN link, and TN-S after that.
So yes, technically we have to confirm that there is a main earthing system any time we connect something.
The reason for this requirement is that there's a good chance that older installations, originally using a metal waterpipe as their earth electrode, may have had the plumbing upgraded - and in the process lost their electrode.
Which is a significant safety issue, as the safety of the entire MEN distribution system relies on each installation having an electrode.
Between them these electrodes keep the distribution N at close to earth potential.
So it actually makes sense that whenever maintenance is done; the existence of the man earthing system (defined as the MEN link, the MEC, and the electrode) should be confirmed.
And you can't do that with an EFLI test.
The EFL for a socket doesn't tell you anything useful about the main earthing system; because the only part of the system that's part of the EFL is the MEN link.
You should be finding the electrode, and the MEC at swbd, and testing that they are adequately connected together.
However I suspect this check is almost never done.
You are correct that no form of polarity test done at a socket using a "polarity tester" can detect a N-E reversal.
However there are other forms of polarity test that can do so. Refer to AS/NZS 3017.
For any fitting replacement (and especially for a socket); if N & E have been swapped, we should find it.
Just in case we didn't actually get those coloured wires in the right terminals.
Everyone makes mistakes; the point being to find them before they cause harm.
If we instead find someone else's earlier error, that's a bonus - we've left it safer than it was
We can't leave it once we've found it, because what matters is not what colour wire we put into which terminal,
but that the E terminal is connected to the E bar and the N terminal to the N bar.
Our work isn't correct unless we prove that;
so doesn't matter who made the mistake, nor when they made it.
A socket is a point that's required to be earthed, so obviously an earth continuity test is necessary.
And by testing that - with trailing lead , and either RCD off or MEN link removed for testing -
you also prove that the N & E haven't been swapped between you and the swbd the circuit originates at.
After that, you can test A(s) & N.
Do N after replacing the link; by measuring N-E at the socket.
(A standard live polarity test can't always show the difference between link in & link out)
Then an EFLI test, if there's no RCD.
Again the EC test will have given you half the info, ie the resistance of the PEC,
so the full EFLI test just confirms that the actives are also low enough impedance for (fault) protection to operate correctly - [73A(e)(ii)]
And note that since there is a supply available, you have to use the 'live" test method.
We're generally only responsible for what we do, not for what happened before.
ESR 13(1)states clearly the extent of our responsibility:
(a) do what you do correctly; and
(b) don't make anything else less safe than it was.
Re: Replace power point testing
Yes, like Alec says if you dont check the polarity of the socket outlets upstream to the one you are replacing you dont know if the wiring has been transposed at them, makes a quick job turn into something a bit longer.
Re: Replace power point testing
Thanks much appreciated.
Pete are you saying you should do polarity test at all sockets in circuit upstream?
Pete are you saying you should do polarity test at all sockets in circuit upstream?
Re: Replace power point testing
I would say technically yes, as you are the last person working on that circuit but hey I am probably wrong, Alec will confirm. I know it also probably wouldn't get checked either.
Re: Replace power point testing
You often won't know which sockets are on same circuit, nor which order they're wired in.
We're not responsible for the fact that someone else may have made an error before we got there,.
We are responsible for testing that polarity of the socket we worked on is correct.
Not so much that the right coloured conductors are in the right terminals: but that each terminal is connected back to the right part of swbd.
If the testing shows that not to be true, we have to find out what's wrong & fix it.
Doesn't matter whether it's our error or whether it's someone else's error - either way we can't leave it wrong.
We're not responsible for the fact that someone else may have made an error before we got there,.
We are responsible for testing that polarity of the socket we worked on is correct.
Not so much that the right coloured conductors are in the right terminals: but that each terminal is connected back to the right part of swbd.
If the testing shows that not to be true, we have to find out what's wrong & fix it.
Doesn't matter whether it's our error or whether it's someone else's error - either way we can't leave it wrong.
Re: Replace power point testing
Hi Alec, yeah you don't know how the circuit is wired but I just thought the power is off while you are changing the ppt, and you have run out a trailing lead to check the polarity so not much more effort to check the power outlets in the area you are working in, you could assume any outlets with no power on are on that circuit hopefully, must admit I have never checked existing outlets when replacing a power outlet but when you think about it it makes sense, especially when you are also checking that a Main earthing system exists.
Image doing this on a high rise building, when you were only called in to replace a power outlet on level 10 for example, what do you think or am I over thinking this?
Cheers Peter
Image doing this on a high rise building, when you were only called in to replace a power outlet on level 10 for example, what do you think or am I over thinking this?
Cheers Peter
Re: Replace power point testing
This has been a good info.
I was a bit unsure about how much testing would be required
Sometimes I have a bad habit of trying to make the rules fit common practises which are not always correct.
When a meter is replaced procedure is only to test polarity and check meter box is earthed and MEN link is in tact via belling out Neutral and meter box ( no actual result required just bell continuity ( only if metal meter box)
No verifying earthing system, protection of supply, efli etc
This seems acceptable, by network, maybe they give the metering a pass. Prob comes from meter outside and customer usually not home( no access)
I though that power point replacement may be similar in that replacing power point will not change the earth resistance or efli
But I understand how you have explained it and it does make sense to me now.
There is no way to tell if something has failed or been changed since Initial install unless all the tests are done every time or faults may never get picked up.
I was a bit unsure about how much testing would be required
Sometimes I have a bad habit of trying to make the rules fit common practises which are not always correct.
When a meter is replaced procedure is only to test polarity and check meter box is earthed and MEN link is in tact via belling out Neutral and meter box ( no actual result required just bell continuity ( only if metal meter box)
No verifying earthing system, protection of supply, efli etc
This seems acceptable, by network, maybe they give the metering a pass. Prob comes from meter outside and customer usually not home( no access)
I though that power point replacement may be similar in that replacing power point will not change the earth resistance or efli
But I understand how you have explained it and it does make sense to me now.
There is no way to tell if something has failed or been changed since Initial install unless all the tests are done every time or faults may never get picked up.
Re: Replace power point testing
Seems to be widespread that networks do their own thing, and often ignore ESRs.
For example, it's very common for mains to be connected - Active(s) & Neutral - to the network, by network staff / contractors, long before anyone has issued a CoC - let alone an RoI - that says the mains are safe to be connected. And the person who connected often doesn't issue an ESC.
But then the network can't be held responsible if something goes wrong, because they mostly use either staff or contractors who have individual PLs.
It's the PL holder who is responsible for ensuring they do the PEW in a compliant manner, and who is liable for safety.
If their staff were under an Employer Licence, then the network company would be responsible.
Difficult access is not an acceptable reason for not doing required testing.
Especially polarity of mains; and existence of MES.
There are NO acceptable reasons.
Worth noting that while networks are required to provide s/c protection & fault protection for mains; they are not required to provide overload protection. That's down to installers, certifiers ,& (especially) persons connecting.
Which is difficult to check, when we typically are not authorised to access the supply fuse.
For example, it's very common for mains to be connected - Active(s) & Neutral - to the network, by network staff / contractors, long before anyone has issued a CoC - let alone an RoI - that says the mains are safe to be connected. And the person who connected often doesn't issue an ESC.
But then the network can't be held responsible if something goes wrong, because they mostly use either staff or contractors who have individual PLs.
It's the PL holder who is responsible for ensuring they do the PEW in a compliant manner, and who is liable for safety.
If their staff were under an Employer Licence, then the network company would be responsible.
Difficult access is not an acceptable reason for not doing required testing.
Especially polarity of mains; and existence of MES.
There are NO acceptable reasons.
Worth noting that while networks are required to provide s/c protection & fault protection for mains; they are not required to provide overload protection. That's down to installers, certifiers ,& (especially) persons connecting.
Which is difficult to check, when we typically are not authorised to access the supply fuse.