Fault finding where to start

[stidge]

Hi all any information will be much appreciated.Quick look at job today,customer says getting shocks off almost everything in kitchen when lights turned on!Only had 15 mins so quick look at CU. TT i Think no RCD,Old CU,Took a quick reading off light switch and sockets(seperate ccts) L - N 240v L- E 167v ? exactly the same on sockets.All you FAULT MASTERS where would you start? Im going back tomorrow to inspect CU Earthing etc JUST WONDERED if anyone had come across anything similar,Thanks

 

[supasparxs]

first of all I would kill all the outward circuits and then check what voltages were present
liven up each circuit until the strange voltages appear

 

[Deleted member 9648]

Livening up circuits until a voltage appears is not the correct way to go about finding this potentially lethal problem.
The whole installation should be isolated and IR tests carried out on all circuits,there will be a low reading somewhere which due to inadequate earthing is causing a voltage to appear where it shouldnt.
Once the IR fault(s) are cleared a proper earthing system and means of earth fault protection should be installed to ensure safe operation of the installation.
This sort of thing is a minefield for a sparks....if the problem cannot be sorted on the initial visit the installation must be isolated and written advise handed to the customer that it must not be energised until made safe.
If you come in and dont sort the problem,leave it live and someone is killed, you will be in a world of woe.
Problems like this have to be sorted properly.....if the customer wont pay for the installation to be made completely safe walk away......half sorting it is not an option.

 

[acat]

As Wirepuller said "dead test" everything otherwise you may become part of the problem and the EAWR requires that. Once you have found the circuit then test it step by step until you find the part of the circuit that is causing the problem.

Good luck and keep us posted how you get on.


Chris

 

[nickblake]

sounds like a lost neutral , if its a tncs system you can get some wiard voltages when you loos e an neutral, split the circuit and do an R1 and R2 test then do it R2 to neutral , you could have a neutral to earth fault to this could cause a back feed and make metal parts live ,so after do a IR test , dont work live do dead tests , doesnt sound like theres any bonding in place , so first start off at the supply and see if you have a decent supply supply and see what Ze readings you have , then work from there, 100 % agree with the other guys comments to

 

[stidge]

Thanks mate will keep you posted

 

[Sintra]

Start by isolating cu and checking earthing system. Check voltages coming into cu L- N, L - E & N - E.

Check Ze.

You could find that this fault is poor main earthing as your fault is common to more than one circuit.

 

[stidge]

Start by isolating cu and checking earthing system. Check voltages coming into cu L- N, L - E & N - E.

Check Ze.

You could find that this fault is poor main earthing as your fault is common to more than one circuit.

Thanks mate much appreciated been today and getting 90v across N E at CU.Narrowed it down to NE fault on lighting cct got to rip floor up friday sound!!!!! cant wait thankls for all your help lads

 

[not clever]

If you've traced it down to the lighting circuit, check that you've not got a trapped conductor between any switch faceplate & metal backbox.

 

[stidge]

If you've traced it down to the lighting circuit, check that you've not got a trapped conductor between any switch faceplate & metal backbox.

HAve done not clever thanks again