New C U Certification

[telectrix]

personally, i always do r1,r2,rN, if only to 1. ensure the |RFC/s have not been split. and 2. to make sure i don't get my tiny mind confused and cross connect the legs in the CU.

 

[spark 68]

personally, i always do r1,r2,rN, if only to 1. ensure the |RFC/s have not been split. and 2. to make sure i don't get my tiny mind confused and cross connect the legs in the CU.

I also do this, but for another reason too, because on a couple of jobs I have had an r2 reading lower than one r1 or rN readings, the cause has always been a loose connection in one of the SO's,
a Zs reading would not show a loose N.

 

[brman]

I've got to admit I don't see why you wouldn't do r1, r2, rn when you change the CU. It is a 30 second job when you have all the wires out and means you can fill in the test schedule fully. Cross coupling and doing R1+R2 is a bit of pain and I can see that a quick check of r1, r2, rn against your Zs tests would do the job there.

 

[telectrix]

had one the other week. r1 = 0.45, r2 = 0.70. rN = open circuit. found it in a S/O, terminal loose.

 

[malcolmsanford]

lol looks like I've lost this one lads ......................but to all of you fair dos for doing the job to the nth degree

 

[brman]

had one the other week. r1 = 0.45, r2 = 0.70. rN = open circuit. found it in a S/O, terminal loose.

ditto, but to be fair Malc said he would test L-N as part of his Zs testing which should pick up the neutral fault.

I also had one the other week on a lighting radial where Zs looked ok (ish) along the circuit but a proper R1+R2 (with earth disconnected at the board) found a break in the cpc. For the 2nd half the circuit the cpc came from the other lighting circuit- connected at at a dual gang switch. You could argue that for a board change, who cares, there was still a cpc at each outlet but it is one that I would want to know about.

 

[spark 68]

Cross coupling and doing R1+R2 is a bit of pain and I can see that a quick check of r1, r2, rn against your Zs tests would do the job there

I have on the odd occasion had a fine r1,r2 and rN reading at the CU, but an iffy reading at a SO when doing the cross connected tests, and found the SO connection loose, but the wires twisted together in the slack terminal.

I tend to just do the full tests because it is my head on the block so to speak, when the assessor told me the only defence I have is my paperwork, I take it the scheme provider won't be in the dock defending me.

 

[telectrix]

the only thing scheme providers would defend is their fat fees.