Help! voltage between neutral and earth

[Lucy79]

I was changing the face plate of the light switch to the outside light, it had previously worked fine. When i turned the electrics back on it didn't work.
I used a multimeter to try and find out what was going on, I had 240v between live and neutral, 240v between live and earth, but intstead of having 0 volts between earth and neutral i had about 107 volts. I checked at the light rose to see what reading I had, the upstairs lighting circuit was normal its just the downstairs lighting circuit thats a problem. I have taken out the downstairs lighting circuit fuse and the fuse board and I was affraid it might be dangerous any ideas?

 

[oharaf]

Where exactly did you take these readings??

 

[Lucy79]

The outside light is spured from the kitchen light rose. The cable runs from the kitchen light rose a switch on the wall and from there a cable runs to the outside light.

I took the readings at both the switch for the outside light, then also at the kitchen light ceiling rose where the cable is spured from. I dont know if its something i have done or it has always been like that, the kitchen light works fine just strange voltage so have turned it all of.

 

[Space cat]

First things first; are you sure that meter reading was 107 V and not 107 mV? I know it sounds stupid but it's an easy mistake to make with an auto-ranging multimeter.

If it really was 107 volts then, since the light works, the most likely cause is a floating earth - and that is dangerous. With power off (like it is now) measure the resistance between neutral and earth. It should be low. Try this at other light fittings and switches around the circuit. You might even stumble upon a loose earth wire in the process.

 

[Spark123]

Where exactly did you take these readings??

I think that I am thinking what you're thinking?

A black wire in the back of a switch is often a switched live. If it is it should have a red sleeve on it but often gets left off or lost.
If it is the switched live and there isn't a lamp in the circuit, the lamp has popped, the switched live is open circuit downstream or possibly a compact fluorescent lamp is present then the readings like this are normal.

 

[oharaf]

Sorry been away at the mother in laws. SOME SICK FATHERS DAY PRANK I think.

Yep I was thinking that 123, however space cat also has a point.

 

[securespark]

The cable runs from the kitchen light rose a switch on the wall and from there a cable runs to the outside light.....

I took the readings at both the switch for the outside light, then also at the kitchen light ceiling rose where the cable is spured from.

She implies there is a neutral at the switch position, then goes on to say that she's tested at both the switch and the origin of the supply to that switch.

I don't think she's testing against a switchwire. But I do think the cpc for that circuit (or part of it at least) is floating.

 

[Lucy79]

I tested the resistance between earth and neutral and it said OL. I will have a look at the other lights downstairs and see if the earth has come out on any of them. Thanks for your advise so far!