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?

 

[telectrix]

the R1+ R2 should be for the whole circuit.i.e. from the OCPD in the DB to the furthest point.

 

[gazdkw82]

Is there any literature (regs/onsite guide) to support this?

 

[Deleted member 26818]

Is there any literature (regs/onsite guide) to support this?

Why would you be recording the R1+R2?
What is the purpose behind it?

 

[gazdkw82]

Why would you be recording the R1+R2?
What is the purpose behind it?

It's part of the minor works testing schedule on our guardian minor works

 

[Pete999]

Why would you be recording the R1+R2?
What is the purpose behind it?

You nee to ensure that the circuit you are adding, altering etc is correct, if the RFC you are adding a spur to, and the R1+R2 was suspect, indicating that maybe it is not wired correctly, then adding a new spur may not be the best option, that's how I read it Spin.

 

[gazdkw82]

Wouldnt it be easier to just do a Zs? If that complies, then the R1+R2 value must be acceptable?

 

[westward10]

18th Ed MWC asks for continuity readings as well as Zs.

 

[Pete999]

18th Ed MWC asks for continuity readings as well as Zs.

Agree Mate, but the question the OP posed, or at least I think this what he is asking, is would you need to take continuity readings of just the new cable installed, or the continuity of the new and existing circuit, my thoughts are post 6.

 

[gazdkw82]

Exactly that Pete.

 

[Nigel]

It's part of the minor works testing schedule on our guardian minor works

I think Spin is trying to point you in the direction of finding the answer yourself.

What is the reason we carry out R1+R2 testing?

 

[Nigel]

You nee to ensure that the circuit you are adding, altering etc is correct, if the RFC you are adding a spur to, and the R1+R2 was suspect, indicating that maybe it is not wired correctly, then adding a new spur may not be the best option, that's how I read it Spin.

I think Spin knows the answer but is trying to help the Trainee.

 

[Nigel]

Exactly that Pete.

What is the purpose of R1+R2 testing?

 

[gazdkw82]

To confirm continuity and polarity

 

[Deleted member 26818]

It's part of the minor works testing schedule on our guardian minor works

Ok, if it’s just to fill out the form, then you should do what the form asks, which is to record the value of R1+R2 for the circuit which has been altered or extended.

 

[Pete999]

To confirm continuity and polarity

Perzaktly Gaz ( not a spelling mistake)

 

[Nigel]

To confirm continuity and polarity

Before what?

 

[telectrix]

but it's not just the form, it's to confirm that there is a cpc to each point

 

[gazdkw82]

Before what?

Energising the circuit.

My question was more a question of where the R1+R2 was performed

 

[gazdkw82]

but it's not just the form, it's to confirm that there is a cpc to each point

A Zs would confirm the same?

 

[Nigel]

To confirm continuity and polarity

Before what?

Energising the circuit.

My question was more a question of where the R1+R2 was performed

Exactly. So before you energise a circuit you want to make sure their is a fault return path in case there is a fault on the circuit or equipement connected to it and therfore ensuring live testing is carried out as safe as it can be.

So with that in mind what would you do now in terms of R1+R2 testing?

 

[Pete999]

Energising the circuit.

My question was more a question of where the R1+R2 was performed

Well I guess the question remains Gaz, do you just test the new bit of cable or the entire circuit, unless you have a test cert of the original it's a mute question, which nobody can give a definitive answer to, yet.

 

[Deleted member 26818]

Well I guess the question remains Gaz, do you just test the new bit of cable or the entire circuit, unless you have a test cert of the original it's a mute question, which nobody can give a definitive answer to, yet.

That is not the case at all.
I have already given a definitive answer.
To whit: Do as the form requires, measure the R1+R2 of the altered or extended circuit.

 

[Pete999]

That is not the case at all.
I have already given a definitive answer.
To whit: Do as the form requires, measure the R1+R2 of the altered or extended circuit.

What does the form say exactly Spin? not questioning it per say just need proof, does it say only the new bit? Show me the proof that it's only the extension that needs testing, with reg numbers etc, and I promise I will shut up honest, I'll be a good Boy and not question it again, unless it's to confirm your findings.

 

[Deleted member 26818]

What does the form say exactly Spin? not questioning it per say just need proof, does it say only the new bit? Show me the proof that it's only the extension that needs testing, with reg numbers etc, and I promise I will shut up honest.

It means all of the circuit, after it’s been altered or extended.

 

[Pete999]

It means all of the circuit, after it’s been altered or extended.

Right so that's the entire circuit Yes. from the CU? I only ask cus it has been a bone of contention for me for some time, so just to confirm, you are adding a spur to a RFC you test the whole circuit, so sorry to sound like a dork, but so many people question my reasoning it's getting to hurt my brain cus I believe you are right, now comes the clincher, where does it say this? I need to know otherwise I wont sleep tonight.

 

[Nigel]

Is this thread an actual joke? Am I on @Pete999 's ignore list???

 

[Deleted member 26818]

Right so that's the entire circuit Yes. from the CU? I only ask cus it has been a bone of contention for me for some time, so just to confirm, you are adding a spur to a RFC you test the whole circuit, so sorry to sound like a dork, but so many people question my reasoning it's getting to hurt my brain cus I believe you are right, now comes the clincher, where does it say this? I need to know otherwise I wont sleep tonight.

It states this on the MEWIC itself.

 

[Pete999]

It states this on the MEWIC itself.

OK sPIN thank you very much

 

[Deleted member 26818]

My reason for checking continuity of RFC conductors after making a spur from the ring, would be to confirm they have continuity after I have conducted the work.

 

[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...