Fault on lighting circuit?

[jason_exact]

Any further thoughts people? If i do get a very low reading on the IR of the lighting circuit what the best way to try and find the fault?

 

[Phil]

start splitting circuits

 

[mogga]

someone has ****ed up on the marking of cores while taking them out??

 

[jason_exact]

Excuse my ignorance but please fill me in.....

 

[Jason Smith]

Hi people,

Changed a consumer unit today to a 17th ed split load wylex. Switched on and all was fine for 10 mins then, rcd tripped by the downstairs lights, switched on again and worked for another 10 mins. Meantime i plugged in several different appliance fridge freezer, hoover, toaster etc and each time i did on the same ring it tripped the rcd.

I then took out the downstairs lighting circuit and this meant the ring which was tripping was fine. I then tried connecting lighting circuit again but it was tripping instantly this time.

I have removed all switches and nothing visible loose or nipped.

Can i have some advice on fault finding the lighting circuit? Please keep it step by step and simple im new to fault finding!

Any ideas how the ring is linked to the appliances being plugged in and the lighting circuit?

advice welcome, please help guys!

Cheers......

lighting can be linked to a ring, if you wanted to you would take a 2.5 off the ring, into a 5 amp max fused connection unit, and then this becomes the feed for the lighting circuit. Has there been a new edition to the house ? dead common are conservatories, new extension etc. Worse case is that they came straight off a jb under a board somewher, or properly there will be a FCU near a double/single socket somewhere.
If the offending circuit lights is not on the same neutral bar as the ring its spurred off of, it will trip.Just in case this is your answer mate. (neutrals in the wrong neutral bar causing an imbalance)
Gotta say this- as I dont know your knowledge level, dont go swopping neutrals about in the board without disconnecting the associated phase will you- the neutral will become instantly live the second you disconnect it.
your suspicions should be well aroused if you have genrally proper light switch drops, but then you find one thats a live to switch behind a face plate- usually a sign its taken off a ring or radial( but by no means certain, just may help you indicate where to start looking for a feed off the ring- nearest floor board etc-which usually has a huge wardrobe sat on it).
Hope this helps.

 

[jason_exact]

Thanks people for the advice, found the fault today.

Tested IR on lighting after disconnecting the 3 lights which were on the circuit. I was left with just the supply to the first light to get a good IR reading of 299Mohms, then connected each switch drop and supply individually and still got good readings. The last supply i connected in was to the kitchen which was the supply which was terminated and this is when i got the fault. I disconnected as this was the last radial and had been terminated in the next room.

There was no cross or borrowed neutral just a fault with the last bit of cable where i guess was damaged somewhere in the ceiling.

Any other advice welcome, cheers