Parallel paths on R1 + R2 test

[DaveS]

Hi there

Doing some testing at moment. R1 + R2 readings coming in lower than R1 + Rn. Cpc neutral and live all disconnected. There is alot of containment on job and adaptable boxes are all fly leaded to earth. My thoughts are they are parallel earth paths but guy working with seems to think because cpc disconnected at board it can' be. Who is right basically? Thanks

 

[Pete999]

Hi there

Doing some testing at moment. R1 + R2 readings coming in lower than R1 + Rn. Cpc neutral and live all disconnected. There is alot of containment on job and adaptable boxes are all fly leaded to earth. My thoughts are they are parallel earth paths but guy working with seems to think because cpc disconnected at board it can' be. Who is right basically? Thanks

What are the r1, rn and r2 readings?

 

[Deleted account]

He is in regard to they cannot be parallel paths to earth, but you are in regard to there may be parallel paths between junction boxes or back boxes dependant on the type on cable management and building structure.

 

[DaveS]

What are the r1, rn and r2 readings?

0.92 on r1 + r2 and 1.25 on the r1 + rn both wired in 2.5mm

 

[Pete999]

0.92 on r1 + r2 and 1.25 on the r1 + rn both wired in 2.5mm

Don't think you understood my question Dave end to end readings r1,r2 and rn as seperate conductors, as described in the RFC testing procedure. From your statement the circuit is wired in singles 2.5mm2,
It could be that you have a poor connection in one of the conductors, proving the end to end resistances will settle the arguement.
Are you nulling the leads at the ends of each test?

 

[telectrix]

if it's in metal containment that will provide a parallel earth so the R2 reading will be the cpc and metalwork in parallel.thus giving a lower reading.

 

[DaveS]

Don't think you understood my question Dave end to end readings r1,r2 and rn as seperate conductors, as described in the RFC testing procedure. From your statement the circuit is wired in singles 2.5mm2,
It could be that you have a poor connection in one of the conductors, proving the end to end resistances will settle the arguement.
Are you nulling the leads at the ends of each test?

Hi Pete I don' think I can do end to end readings as over multiple floors? The leads were nulled yes. Have just tested a seperate circuit and how similar readings with a 0.30 lower difference again with r1 + r2 this does parallel paths no?

 

[Pete999]

Hi Pete I don' think I can do end to end readings as over multiple floors? The leads were nulled yes. Have just tested a seperate circuit and how similar readings with a 0.30 lower difference again with r1 + r2 this does parallel paths no?

You can do end to end testing at the CU Dave

 

[Pete999]

You can do end to end testing at the CU Dave

You can do end to end testing at the CU Dave

 

[Pete999]

You can do end to end testing at the CU Dave

 

[DPG]

Hi Pete I don' think I can do end to end readings as over multiple floors? The leads were nulled yes. Have just tested a seperate circuit and how similar readings with a 0.30 lower difference again with r1 + r2 this does parallel paths no?

I'm confused how this could affect the carrying out of end-to-end readings. I might be missing something.

 

[DaveS]

It' a lighting circuit?

 

[Pete999]

I'm confused how this could affect the carrying out of end-to-end readings. I might be missing something.

I think the only thing missing is competence!

 

[DPG]

Ah, you never said. Must admit I assumed RFC. Multiple floors doesn't affect testing though still.

 

[Pete999]

It' a lighting circuit?

Might have said something earlier Mate, or perhaps we could have used my Crystal ball. sorry but I'm out of this one.

 

[Pete999]

Hi Pete I don' think I can do end to end readings as over multiple floors? The leads were nulled yes. Have just tested a seperate circuit and how similar readings with a 0.30 lower difference again with r1 + r2 this does parallel paths no?

End to end readings are for RFCs, this is where the confusion comes from, if you had mentioned that it was a lighting circuit the confusion would have come to the for earlier, you may need to brush up on your testing procedures Mate, the question begs, how did you get your R2+R2 results?

 

[Pete999]

Hi Pete I don' think I can do end to end readings as over multiple floors? The leads were nulled yes. Have just tested a seperate circuit and how similar readings with a 0.30 lower difference again with r1 + r2 this does parallel paths no?

End to end readings are for RFCs, this is where the confusion comes from, if you had mentioned that it was a lighting circuit the confusion would have come to the for earlier, you may need to brush up on your testing procedures Mate, the question begs, how did you get your R2+R2 results? Message to oneself don't assume anything or that anyone knows what they are doing.

 

[westward10]

Now we know it is a radial then yes any metal containment will affect readings due to parallel paths unless you isolate the cpc from the containment. Disconnecting the cpc at the board will have little effect unless the cpc goes to a single point of utilization.

 

[Pete999]

Now we know it is a radial then yes any metal containment will affect readings due to parallel paths unless you isolate the cpc from the containment. Disconnecting the cpc at the board will have little effect unless the cpc goes to a single point of utilization.

Deleted

 

[MFS Electrical]

Hi there

Doing some testing at moment. R1 + R2 readings coming in lower than R1 + Rn. Cpc neutral and live all disconnected. There is alot of containment on job and adaptable boxes are all fly leaded to earth. My thoughts are they are parallel earth paths but guy working with seems to think because cpc disconnected at board it can' be. Who is right basically? Thanks

There could be parallel paths if the conduits are straight into the board or into trunking and the trunking is bonded and the building structure can also create a parallel path to earth