Lights tripping

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paul b b

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Hello Guys,

I have to go and see a chap on sat, his light are tripping and i just wanted to confirm a few things before i go.

If it is the mcb tripping is it most likely a live nutral fault?

if the rcd is tripping is it most likely a live earth fault?

and the easyest way of finding the fault (r1+r2 for live earth fault i suppose)

any advice would be most welcome as its my first real fault finding mission!

Paul

 
an MCB tripping could be either L-N or L-E, but if the RCD doesnt trip, more likely L-N

RCDs will not trip on L-N fault

R1R2 will be of no help. you need IR. once fault is known, split circuit half way, test again. one should be clear, one will have fault. split again and keep going. slight different process for rings though

 
Paul .. If IR tests check out o.k. then.check for loose connections [starting inside the C.u first]..and work outwards if necessary..it may not necessarily be a short on the wiring or accessories.

 
Hi

Firstly check for the obvious ie Old light fittings.

Ask if there is a light that causes the protective device to trip. Cheap bulbs will trip a Protective device often if they blow.

Remove each fitting and try to reset Protective device each time.

If the fault was in the wiring then the Protective device would not reset so aviod getting the tester out stright away

 
More info needed, how often is it tripping, when does it trip, does it always trip when a certain or certain lights are put on.

Batty

 
Also, how is the best way os spliting and doing a ir test? Put cables in to connector blocks? And I do it with the cables still in the mcb or will if affect other circuits?

Thanks again

 
dont forget to switch all light switches on when doing IR then you test the switch wires.

 
Also, how is the best way os spliting and doing a ir test? Put cables in to connector blocks? And I do it with the cables still in the mcb or will if affect other circuits?Thanks again
go to the light which will be about middle of circuit. disconnect wiring (making note of sw. live) and test

no need for connector block. just leave them hanging (your testing is done dead anyway)

 
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