Structure of Continuity of CPC Question - Basic

[dtombs]

Hi, just wondering if anyone thinks if this would be alright for a basic structure to a question in a 2391 exam asking how to carry out a "Continuity of Protective Conductors Test Method 1". Thanks in advance.

Dan.

Continuity of Protection Conductors (Including Main and Supplementary Bonding) – Method 1
1. Select a Low-resistance Ohm Meter, checking the battery condition, lead condition and up-to-date calibration certificate.
2. Isolate Circuit to HSG-85 requirements and place signs/notices and barriers where appropriate.
3. Connect the line conductor to the protective conductor with a temporary link at the distribution board or consumer unit to include all of the circuit.
4. Test between line and earth terminals at each outlet on the circuit checking for continuity.
5. Remove Temporary link between line and protective conductors at distribution board/consumer unit.
6. Record the result at the circuits extremity as “(R1+R2)” value on the schedule of test results

 

[roukel01]

Seems good, the only thing perhaps is that you should mention that switches on lighting circuits should be in the on/closed position.

 

[ezzzekiel]

always remember to mention "null test leads" they always pick up on that

 

[dtombs]

Thanks for the advice guys, I'll take that on board and ammend my procedure listings.

Dan

 

[GrannySmiff]

Don't you only record your highest r1+r2 and record where you took your reading which as you say extremity is usually last point in circuit as you will then test your Zs there?.

Also as this is a dead test are you explaining that it is, do you need to mention it is isolated at all?

And do you need to mention that the readings need to be acceptable, I am not sure yet of what is unacceptable but surely should be mentioned.

Have you mentioned how to test the bonding as well? it seems to only talk about the circuit but I think I am thinking of an R2 test.

 

[dtombs]

The GN3 book uses the word 'extremity' which basically is the last point on the circuit that you can test from.

I mentioned in step 2 that the circuit needs to be isolated according to the requirements of HSG-85, I suppose you could put as an extra step "safely disconnect load from circuit" as well.

I forgot to mention step 7 which would be along the lines of "Compare test result values with calculated values to confirm the circuit is safe to operate".

I think testing bonding conductors is a seperate test altogether, involving the physical inspection to ensure mechanical soundness as well as an R2 continuity test.

Dan.

Thinking about it, would you actually need to state "Disconnect load from circuit" if you've already mentioned that you've isolated it?

Thanks.
Dan

 

[Jason Smith]

Am I missing something, The original question is about continuity of the CPC, We simply disconnect both ends and measure the resistance, then calculate its about right with the known resistance for a given length of conductor. (wander lead and all that ) .
Or is it me thats misread the question (likely ). If anyone thinks I am right, I will expand mate on how to do it.