Discuss Minor works R1+R2 measurement in the Electrician Courses : Electrical Quals area at ElectriciansForums.net

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Hi - at risk of getting shelled, here's a conversation starter : the MEIWC part 4 calls for R1+R2 ... or ... R2. With the modified circuit safely isolated at the board, would it be acceptable to use a wander lead back to MET to get R2 ? (so the cover is never taken off the board).
 
Ok seems we are up for debate on live working, although I think I will be the only one debating this side of the fence and not withstanding we are all competent professionals.

Why should we? Not withstanding the caveats like taking the ends of the probes of my G38 voltage tester, unscrewing a face plate and check its dead etc, chaps having to work on dno cables etc, or perhaps in a hospital environment (still debatable).

So why would you. There, got the ball rolling.
 
Because sometimes it's necessary and providing you are sensible about it and take the appropriate precautions it can be done quite safely with minimal risk.

Before I start poking around in a live board, I always give it good look through and after that, if I can do what I want to do safely with minimal risk I proceed. If not, I ask the customer if I can turn it all off... if I can, groovey, if not I enquire when I can and potentially schedule a mutually convenient time for the work to be carried out.

The old Wylex BS 3036 boards I'm not keen on working on live because of the abundance of bare metal and close proximity of some of those exposed conductive parts (but even after turning off the main switch, there is still a significant risk).

I have had some close calls where idiots have damaged the incoming tails leaving the bare conductor exposed at the rear, thankfully had a good look before I stuck my fingers in there but you can't so readily turn them off, so what do you do in that kind of situation?
 
Don't you need to take the board cover off anyway to measure insulation resistance of the altered circuit? Or are you using double pole protective devices?
 
I think it's a necessary part of what we do sometimes. As long as you are working within your RAMS. Sometimes it's necessary to work on or around live parts. Fault finding is a good example.

Nowadays most CU are all IP2X internally so there is practically zero chance of electric shock
 
There is an element of risk to everything we do I suppose, just ask Prince Philip. It’s how you negate those risks; like he should have someone else drive him to places.

In a normal situation, there is no reason to work live. You would to ask why then, in other circumstances, you are required to work live.

For example, in a domestic environment, I can think of very few examples (if any) requiring working inside an unisolated CU.
 
agree. it's no use confirming that your new has a correctly installed cpc if it is not continuous back to the CU and hence the MET.
 
Some instances it's completely unavoidable. For example, opening trunking to that enclose numerous circuit wiring. You may isolate the circuit your working on but all the other circuit wiring is live.

I've opened trunking before to be greeted with bare copper ends.
 
Some instances it's completely unavoidable. For example, opening trunking to that enclose numerous circuit wiring. You may isolate the circuit your working on but all the other circuit wiring is live.

I've opened trunking before to be greeted with bare copper ends.
That is very worrying.
I can see that there are going to be many revelations in that workplace that are going to bother your conscience.
 
just because it's been mentioned a few times and not corrected - a Zs test does not confirm that the CPC is earthed correctly and can not be relied on.
The simple reason is that the apparent earth may be provided via bonding for example an under sink water heater through a metallic pipe.
Any alterations to the plumbing system can render that useless straight away.
 
I spoke with guardian today. They informed me that R1+R2 must be taken from the point of circuit origin.

I have emailed all higher management/technicians and informed them that this is the standard requirement for testing.
 
Well this is just getting confusing now. It really is a grey area.

Our electrical technician has said the contractors we use onsite have said they have spoken with NICEIC and they have said all they need to do is test the leg they have just installed.

I phoned the NICEIC myself and they said it depends on what work has been done. If we are spurring off the load side of a spur then we just test that little section and make a note on the test sheet.

IV just had an email response from a email I sent to guardian over a week ago.

Below is the response. Contradicts what they told me on the phone.

Minor works R1+R2 measurement IMG_20190125_095401 - EletriciansForums.net
 
Yes. It's highly frustrating. There must be some literature that settles this somewhere.

I don't see how you can be sure the cpc goes back to the MET without an R1+R2 of the entire circuit

It is clear and if it is not a cpc or a R2 unless it is connected to the MET. If it is not it is just a bit of copper in a cable.
 
I personally think that you basically have to be satisfied that the r1+r2+ze complies with ADS requirements. Enough to sign your name to it on the certificate. in an installation that is well controlled you could demonstrate compliance by using the documentation available from previous dead testing plus your new partial testing using notes on the certificate to explain your route to compliance so that the documentation as a whole represents the situation.
If the installation has had evidence of unprofessional modifications etc then it would not be professional to alter it without a full test.
As with everything in life you have to follow the rules unless there's a reasoned/risk assessed justification not to. If you can do the risk assessment then you can defend it in court;)
 
How about measuring R2, with a wander lead , between the furthest part of the new circuit and the earth terminal of a socket that is close to the consumer, but definitely on another circuit? R2 value will be high, by the R2 of the socket circuit, but will at least confirm the continuity of the cpc.
 

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