Minor works R1+R2 measurement

[gazdkw82]

I think I may have asked this question a while ago but not sure on what the answer was and it's come up again at our monthly tool box talk.

When doing a Minor works for an additional spurred socket or extra light fitting on a circuit, should the R1+R2 measurement be taken from the protective device or the socket/fitting you have spurred from?

 

[Pete999]

That's what I assumed in post 6 spinlondon, have just clarified that thank your for pacifying an old Furt despite disparaging comments from certain members, cleared up now, just goes to prove RTFM works wonders cheers Mate.

 

[gazdkw82]

It states this on the MEWIC itself.

Does it?

I will check on ours tomorrow but I don't think it does

 

[Deleted member 26818]

PART 4: Test results for the circuit altered or extended (where relevant and practicable).

 

[Nigel]

Does it?

I will check on ours tomorrow but I don't think it does

It does not matter what it says on the cert. You must check there is a full fault return path prior to energising the circuit for safety reasons. You can only do this by testing the whole circuit. If the R1+R2 was complete in your new works and broken in the existing circuit you would be energising a circuit with no earth present and you could make exposed conductive parts live.

This will be taught to you when doing the testing parts of your course.

 

[gazdkw82]

It does not matter what it says on the cert. You must check there is a full fault return path prior to energising the circuit for safety reasons. You can only do this by testing the whole circuit. If the R1+R2 was complete in your new works and broken in the existing circuit you would be energising a circuit with no earth present and you could make exposed conductive parts live.

This will be taught to you when doing the testing parts of your course.

Yes I understand that and it makes sense. However, if there are previous current records for the circuit and a Zs was taken prior to the work, would another R1+R2 need to be taken?

Im not trying to be awkward but this has caused many in depth conversations at our work place. We have a very big hurdle when it comes to taking the cover off a board. Basically we cannot work live in any circumstances. Alot of our buildings run experiments/cooling etc and electricity can not be turned of. So for that reason we are looking at ways we can do a minor works for small remedial works without having to isolate an entire installation.

 

[Pete999]

PART 4: Test results for the circuit altered or extended (where relevant and practicable).

Agree now

 

[Deleted member 26818]

Yes I understand that and it makes sense. However, if there are previous current records for the circuit and a Zs was taken prior to the work, would another R1+R2 need to be taken?

Im not trying to be awkward but this has caused many in depth conversations at our work place. We have a very big hurdle when it comes to taking the cover off a board. Basically we cannot work live in any circumstances. Alot of our buildings run experiments/cooling etc and electricity can not be turned of. So for that reason we are looking at ways we can do a minor works for small remedial works without having to isolate an entire installation.

That’s why the form says “where relevant and practicable”.

 

[gazdkw82]

That’s why the form says “where relevant and practicable”.

So where it's not practicable (cannot isolate the entire circuit) it can be omitted?

 

[Nigel]

Yes I understand that and it makes sense. However, if there are previous current records for the circuit and a Zs was taken prior to the work, would another R1+R2 need to be taken?

Im not trying to be awkward but this has caused many in depth conversations at our work place. We have a very big hurdle when it comes to taking the cover off a board. Basically we cannot work live in any circumstances. Alot of our buildings run experiments/cooling etc and electricity can not be turned of. So for that reason we are looking at ways we can do a minor works for small remedial works without having to isolate an entire installation.

I am certain nobody is thinking you are awkward. Now that you have explained your reason for posting this thread it will open up a good debate.

Personally my view is that for anyone to say 'no live working' to an electrician clearly does not understand what the role of an electrician is. If they do not understand the role of an electrician how can they be competent to insist certain working practices should not take place? Because, by definition, we must verify a circuit is safe BEFORE energising that circuit. To go straight to a Zs test means that you are energising a circuit not-knowing if it is safe and this, to me, sounds like an unnecessary risk.

Scenario - you add a socket from an existing socket in plastic conduit. The socket is metal and has a metal, surface back box. You have checked your R1+R2 on the part of the circuit that only you have touched and it is fine. You screw back the front plate and the screw catches the live cable. Unknown to you, last week a job was done on the circuit and the CPCs were not put back correctly. You energise the circuit and then go back to get a Zs. You then get an electric shock from the socket.

It is essential that testing takes place and part of testing is live working. Part of fault finding is live working.

I would be challenging this rule and suggesting to your employers that it is dangerous not to be testing in-line with approved practices and highlight to them the potential dangers of not doing a proper R1+R2 test.

 

[gazdkw82]

Yes, it's been something we have all challenged. To say we are not competent enough to work around a live environment is odd. I think it must be driven from an insurance perspective.

Either way, a simple minor works turns into a real challenge. We already have to arrange times for the work to be completed around the building managers, then arrange for any isolations, gain isolation permits/RAMS etc etc...

 

[Wilko]

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).

 

[gazdkw82]

Most MET's are within the CU so maybe wouldn't work but i think it's a great idea

 

[Midwest]

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.

 

[Deleted member 26818]

I guess for a lot of us, it’s because it’s what we’ve always done.

 

[SparkyChick]

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?