voltage appearing between earth and neutral on lights???

[crazyface]

Hi, i have been having trouble for a while now with the bulbs in my living room lights continually blowing. So i had a friend come over and he tested at the light and found 60 volts between neutral and earth when the switch is off, and 180 volts when the switch is on. also the earth at the switch is showing as live? the lights are wired in single neutrals and a live/earth cables in steel conduit.

any thoughts??

many thanks

 

[ericmark]

Back in the 1960's lights were often not earthed and likely if one was to use an earth loop impedance tester you would find at some point the earth is not connected.

This is unlikely to cause any bulbs to blow although arcing can due to repeated switching of power reduce bulb life it is more likely to be over voltage from the supplier.

What you need is a lamp able to take varying voltage and if there is no earth you will not find any florescent tube light that can be used. You will need class II lights if no earth. There are some 2D lamps which are class II but you will need the electronic type to get around the voltage problem.

Some energy saving lamps are also electronic and will work better than bulbs as far as life of unit goes however some are not electronic and if voltage varies may refuse to light so I would just buy one at a time until sure that make works OK.

The meters required to test are expensive unlikely any DIY man has one so you really need to get an electrician to test it all for you. If 1960's wiring there may be other faults as well so getting it checked is the way forward.

 

[Adam_151]

There are some 2D lamps which are class II

You'll be replacing them in a few years time when the plastic gear tray turns brown and brittle from the heat and UV of the lamp next to it. and the drops apart around the lampholder when someone tries to replace a lamp.

 

[tiggerinpoole]

Hi, i have been having trouble for a while now with the bulbs in my living room lights continually blowing. So i had a friend come over and he tested at the light and found 60 volts between neutral and earth when the switch is off, and 180 volts when the switch is on. also the earth at the switch is showing as live? the lights are wired in single neutrals and a live/earth cables in steel conduit.

1: What are the bulbs that keep blowing...! GU10 have always had problems with voltage spikes and cheap low energy lamps are normally ratted only for 220-240V (don't be surprised to find your voltage at 245V).

2: Was all the other lights off and the fuse disconnected when you tested the voltage on the neutral..! Remember that the neutral is the 'return' path for the circuit and therefore should be measuring a voltage if it is in use. i.e. lamp on.

3: You say the earth is showing live, what was the voltage reading?? I take it you do not have rcd protection on the circuit as it sounds like you have a pinched neutral at a light fitting and switch supply at a light switch. This is perfectly normal with diyrs and lighting.

4: sounds like you need to get your friend to bring a insulation test meter around and test correctly all your circuits and then I would drop all the switch fronts to check there is not trapped/pinched cables.

 

[Spark123]

As ericmark says, get an electrician to test R1+R2 as it sounds to me like there is a floating earth somewhere.