Discuss Minor works R1+R2 measurement in the Electrical Courses and Electrical NVQ's area at ElectriciansForums.net

gazdkw82

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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

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

Pete999

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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.
 
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gazdkw82

gazdkw82

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

westward10

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

Pete999

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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.
 
N

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.
 
D

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.
 

telectrix

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

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

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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.
 
D

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

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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.
 
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D

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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

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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.:D:p:rolleyes::):):):):)
 
D

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.:D:p:rolleyes::):):):):)
It states this on the MEWIC itself.
 
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D

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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

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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.
 
D

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

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.
 
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gazdkw82

gazdkw82

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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.
 

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