Electrical Installation Installation and Testing

[Casterbridge]

I am going through the process of ripping out some old, extending, and installing new circuits in a flat.

Building control were informed and have accepted my competance, subject to payment and them checking my work etc.

I am coming towards the end of my testing and wanted to ask a couple of questions if anyone can help me please.

Continuity, Insulation, Polarity done

1. Ze measured at CU at 0.14 - From the forms it seems acceptable simply to add the r1+r2 to this to get the Zs - and therefore I assume there is NO requirement to actually conduct the Zs test from a far end of any of the circuits - is that right?

2. I have completed the RCD testing from the furthest socket on the ring for one side of the CU and from the furthest socket on a radial which sits on the other side of the RCD. I don't believe there is any requirement for RCD testing using the other circuits. Is that right.

3. I think I can have a fair crack at completing the forms, given the test I have conducted, which seem to be the Electrical Installation Certificate and the Schedule of Test Results - Are these the correct forms to complete?

I plan to give building control a call for a visit and a sign off, so would like to have everything they need bfore they arrive.

Thank you.

 

[GaryMo]

1. Ze measured at CU at 0.14 - From the forms it seems acceptable simply to add the r1+r2 to this to get the Zs - and therefore I assume there is NO requirement to actually conduct the Zs test from a far end of any of the circuits - is that right?

Yes, that's right apart from it's R1+R2 (there is a difference).

2. I have completed the RCD testing from the furthest socket on the ring for one side of the CU and from the furthest socket on a radial which sits on the other side of the RCD. I don't believe there is any requirement for RCD testing using the other circuits. Is that right.

Test the RCD at the board with all outgoing MCB's switched off.
Just test at half, 1x and 5x at both 0 degrees and 180 degrees, recording the highest figures for 1x and 5x. Half shouldn't trip. Do that for each RCD.

3. I think I can have a fair crack at completing the forms, given the test I have conducted, which seem to be the Electrical Installation Certificate and the Schedule of Test Results - Are these the correct forms to complete?

Yes, along with a schedule of inspections.

 

[RF Lighting]

1. Ze measured at CU at 0.14 - From the forms it seems acceptable simply to add the r1+r2 to this to get the Zs - and therefore I assume there is NO requirement to actually conduct the Zs test from a far end of any of the circuits - is that right?

Yes that's correct, but I still to prefer to see to circuit properly Zs tested.

2. I have completed the RCD testing from the furthest socket on the ring for one side of the CU and from the furthest socket on a radial which sits on the other side of the RCD. I don't believe there is any requirement for RCD testing using the other circuits. Is that right.

RCDs should be tested in isolation i.e. with all outgoing wiring disconnected.

3. I think I can have a fair crack at completing the forms, given the test I have conducted, which seem to be the Electrical Installation Certificate and the Schedule of Test Results - Are these the correct forms to complete?

Yes that's correct. Blank forms can be downloaded from the IET website.

I plan to give building control a call for a visit and a sign off, so would like to have everything they need bfore they arrive.

Thank you.

Did you contact BCO before you started your work?

 

[Taylortwocities]

1. Ze measured at CU at 0.14 - From the forms it seems acceptable simply to add the r1+r2 to this to get the Zs - and therefore I assume there is NO requirement to actually conduct the Zs test from a far end of any of the circuits - is that right?

Yes that's correct, but I still to prefer to see to circuit properly Zs tested.

Indeed. The IET forms just say to state Zs, but the forms I use actually say
"Maximum measured Zs"

If you are using a no-trip loop impedance meter, be prepared for a big difference between the measured and the calculated (R1+R2) + Ze

 

[Casterbridge]

OK - thank you.

1. OK - I think I was using the wrong teminology for R1+R2 - so I think I understand what you mean - r1+r2 is the figure of eight tests for the ring which will be 4 x the R1+R2 readings which should be inserted on the form.

2. Yes BC were informed, they've had their money and already paid a visit to inspect at first fix stage.

 

[Casterbridge]

If you are using a no-trip loop impedance meter, be prepared for a big difference between the measured and the calculated (R1+R2) + Ze

and that's exactly why I want to calculate the Zs rather than put the result of the no-trip - the measured Zs is still more than acceptable (0.67) but is still higher than Ze +(R1+R2).

If I put in the measured results BC would raise an eyebow wouldn't they?

 

[RF Lighting]

I normally bypass the RCD for Zs testing now as my no trip Zs readings were not reliable.

 

[Casterbridge]

Thanks Gary - yes done the 1/2, 1 and 5 at 0 and 180 and they all look fine, but haven't done it at the board, so will do that too and take the highest.

 

[GaryMo]

If I put in the measured results BC would raise an eyebow wouldn't they?

No problem at all with calculating or measuring Zs.

 

[Casterbridge]

I normally bypass the RCD for Zs testing now as my no trip Zs readings were not reliable.

hmm - what does that involve?

 

[GaryMo]

I normally bypass the RCD for Zs testing now as my no trip Zs readings were not reliable.

That's not recommended due to the potential of forgetting to remove the link (it can happen).
It's a pointless exercise anyway considering you've already done both tests (Ze and R1+R2).

 

[RF Lighting]

Swap the RCD for a main switch. It only takes a few seconds.

 

[Spark123]

If I put in the measured results BC would raise an eyebow wouldn't they?

Probably not, as long as the figures do not exceed maximum measured Zs figures as stated in the on site guide / GN3 I don't see an issue.

 

[maltaron]

You don't actually need to do any testing for the BC. If the work is done under building regs they do the testing. When I wired my kitchen extension I carried out all dead & live tests but when the LA electrician came to check it he was'n't interested, he did his own live tests and passed it.

 

[Casterbridge]

You don't actually need to do any testing for the BC. If the work is done under building regs they do the testing. When I wired my kitchen extension I carried out all dead & live tests but when the LA electrician came to check it he was'n't interested, he did his own live tests and passed it.

Think it may be different for different BC, cos when he did the first fix visit, we talked about the tests I would be doing, and he said once I'm done he'd put his tester on some of the circuits to check the work. I got the impression he would simply be checking rather than compeltiong all of the tests, because he saw that I had the red 17th edition book, and whie it was out of date, he said the forms would be the same, and I could use those.