Electricians

[Shadow Beast]

After some advice, Lights tripped yesterday afternoon in cottage, so today I went to have a look and sort it out, however...... There is an Earth Leakage Circuit Breaker in the system, I know these are no longer installed, I did the usual visual checks and when I come to test between Earth and Neutral I am getting between 56 and 70 volts! Not good, now If it was a Dead short than more like 230 volts, So what is likely to be causing this? I have checked all dimmers and all outside lights, The problem is its only got one lighting circuit in the cottage that runs all the upstairs and downstairs lights and in 5 of the 9 rooms they are all wall lights.

 

Apart from now taking every fitting off and every switch to check is there anything else to do?

 

My concern is if the loop in system is to the center of the ceiling and there is a junction box good knows how i am going to get to it.

 

Answers on a post card please!!

 

Oh the fuse board is an old rewireable type.

 

Richie

[kjgreen3]

Ok don't panic, but you could seriously do with a full test and partial rewire

 

But you could diagnose the fault yourself and maybe get an electrician to come and fix that.

 

1. Are you sure its the lighting circuit and not the ring main(sockets) as they are more likely to give earth leakage currents with appliances like washers dryers etc.

 

2. Unplug everything, I mean everything then unscrew every lightbulb in the property and turn on every switch (to test wiring up to lights). Redo earth to neutral voltage test and get back to me.

 

NB. Make sure you have a torch and normally I wouldn't advocate a non-competent person (techno speak for non-electricians) to be carrying out checks like this. Please be careful!!!

[Shadow Beast]

Sorry mate, should of made myself a little clearer, I am a sparky by trade and yeah done all of the above,

 

Its defo on the lighting circuit as I have tested all the others out and they all run true, and the ELCB holds in. Its only on the lighting circuit that I get the voltage across the earth/neutral.

 

I have removed every light bulb there is and done the switching including the 2 way. I have even done a buzzer test and yet I dont get a noise between earth/neutral although I get up to 70 volts, very strange.

 

Its going to need a rewire I am sure, but weather they will run to that I am not sure at present, I am back there tomorrow to go up in the loft and do a visual of the cables up there as its a thatch roof and I am concerned about mice or rats (which they have had) eating or chewing the cable.

 

Whats your thoughts now? I am stuck................................

[danny1987]

i had a problem like this before, these can trip if the is a fault next door, because the fault from next door would travel down the earth cable, then for example on to the water pipe and trip next doors trip because the were connected by the same water pipe. i got really confused by this and i had to ask one of the older members on my firm what to do, they said to change the Earth leakage circuit breaker or voltage operated trip as its also know, for a 30ma DP RCD, and mine never triped again.

 

Hope this helps

 

Dan

[kjgreen3]

You could megger the lighting circuit with it physically separate from the Consumer unit L-E, N-E and L-N after all the bulbs have been taken out and switches on 'AGAIN' lol. If you have a fault (low reading but not quite zero eg 0.1M etc) you know its on the cable somewhere and I would suggest splitting the circuit roughly halfway and testing again to see if you can isolate it to a particular feed to a switch, JB, light fitting etc.

 

If it bells out clear (at least +7M ohm) then I would go with what danny1987 has suggested. I take it its a TT system. If so I would suggest you change it to TNCS if you are able to and at least put a split load board in 30mA RCD naturally and remove the ELCB but still be well within 17th Edition.

[Shadow Beast]

Thats the plan for tomorrow, to megger stuff out, the problem is to find the rough half way point, easier said than done lol! the loft does not even have joists, its thick branches!!!

 

But if the fault cant be found you cant just change to a RCD as its still going to be there your just masking the problem? The ELCB is working fine, its just now trying to find where a live wire is touching an earth wire.

 

Where the hell do you decide to split a house in half that has 9 rooms? I am going up in loft tomorrow and hopefully it'll be clearer up there as to the wiring, going to also check the switches as there is the possibility that the feeds go to the switches then only a switched live to the lamps,

 

If I have to change the board it will be a bloody nightmare, there is 3 dis boards in this little cupboard and well....... it wont be funny!!

 

Oh cheers for the advice so far guys, dont go away just yet as i will prob be back tomorrow evening!!!!!!

 

Richie

[Shadow Beast]

Well only just got home from the job again, it turns out there is 11 rooms being fed off one 5amp fuse, and most rooms have between 2-4 wall lights, Today we managed to check all the upstairs lights, and find the feed to the first light, it then branches left and right to other fittings, the upstairs is fault free apart from testing the feed cable which we have still to find the other end of.

 

We have narrowed the fault to 3 rooms downstairs (or maybe the upstairs feed cable) all of which have wall lights so there is somewhere a JB under the floor boards for poss 3 rooms, not good news as the cottage is 300 years old!

 

Voltage today between earth/neutral was up to 175 volts, and readings where between earth/neutral 0.02 megohms, and phase/earth 6.8 megohms.

 

Just waiting for customer to decide on when they are happy for floor boards and carpets to come up!!

 

Oh the joys

 

Richie