qouting for a new cu and borrowed neutrals

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changed a 3036 fuse board for a dual rcd today. frigging borrowed neutrals, 2 of them

Does any body include a caveat in their quote for this occurance. You can can hardly do an electrical separation test on each circuit before you quote. unless you do and i'm missing something.
 
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Did you ever find a borrowed neutral when doing a PIR??

They usually only show up once the new board is in and someone switches on the security light over the back door.

(You know, use the CPC on the kitchen lights circuit as the return and pinch a neutral from the upstairs ring :cry:
 
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RF, i didn't do a periodic. I do include many caveats in my quotes and when in a quote situation I want to get the balance between doing everything absolutely correct and being able to offer free quotes and keeping prices low. I spent 1 and a half hours on the quote, i did Ze, pfc, insulation resistance tests, identified all the circuits and their numbers, light bulbs, neon, boiler circuit, ta boot out and all. i did 4 sample Zs's. But as a result of winning the job with as the customer said "a professional approach". I fitted new cu and got rcd trips. You know when you get the answer "well it was all right before you changed things".

So after nearly exactly what taylortwo cities said, and a few splinters it got sorted.

imagine the euphoria of finding the first one and then the trip again :cry: :eek:

I maybe wide of the mark here but who does an electrical seperation test on all circuits on a quote
 
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Nobody used to bother, they wouldn't show if the lights were in the incorrect state either - I know you need to check IR with 2 way switching in both positions. You suddenly end up with a lot of tests if you needed to test across to other circuits.
I'm wondering if something like this would show if you put a clamp meter around the phase and neutral for a lighting circuit, then switched all the lights on - the clamp meter should show the difference between L&N unless it is a fancy that can discriminate between them - I'm thinking the same principle as how an RCD works.
Bar dodgy wiring, one common one to find is the upstairs landing light has the phase from downstairs light circuit.
 
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that was the other one spark123, the landing. Me thinks you will be on dragons den with a mini clamp meter.
 
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that was the other one spark123, the landing.
Don't do PIRs, of course, but if I did I think I'd always check how the 2-way landing light switching was wired if the house had separate lighting circuits.

2 minutes work.

Remove hall switch - if you see the COMs linked, and a 2-core heading off from the landing L1&L2, be very afraid...
 
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You can always do what the electrician did in my parents house.
Wet room being fitted needs a RCD phone call from electrician only cost another £150 to what already paying for him to change consumer unit to larger one rather than use Henley Block. Before 17th Edition. I said yes for that price why do it latter. Visited to see how he was getting on with job RCD tripping. He thought faulty RCD. I found spare for him to try same problem he put in Isolator as a temporary measure. Never seen again! My dad had paid him up front. I then had to sort it all.
 
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Taking up sparks123 idea.

Ensure all circuits have some load, eg. couple of lights on each lighting circuit and a table lamp per power circuit. Then at the cu turn off an mcb and check for currrent on its associated neutral. If theres a borrowed neutral you will get a current reading, no borrowed neutral no current reading.
Only problem I'd have with using direct measurement with this is you could end up with 240v on the neutral when you disconnect it and give yourself a rattle.
 
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You have three options:-
1) Buy an expensive Hall effect clamp on ammeter able to measure 15ma and DC.
2) Do a full PIR before the change and where customer refuses make it very plane any extra work which becomes apparent after the consumer unit if fitted will incur an extra charge.
3) Consider the times when one has problems are too few to worry about and accept every round and again you will make a loss.

I looked at Hall effect clamp on meters and decided I could manage without one. Same as earth rod testing meter not got one of those.

But in 30 years only ever used one on one job. So you have to weigh up pros and cons. With relays, and electronics in so much equipment it is not possible to test everything dead. And anything with timing is likely to cause problems for washing machines to PIR controlled lights and even with a Hall effect clamp on you are bound to miss some faults.

But if washing machine is faulty that's not covered in price so why should any other faulty equipment?

So to my mind to say "When consumer units are changed this often highlights other faults. I am willing to spend up to an hour to try to cure any existing faults after that time any work will be charged for" seems quite fair.
 
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I think the landing light one is a pretty common problem, only comes to light (excuse the pun) when the lights are connected to separate RCD protected circuits.
 
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