Low Voltage reading between mains Neutral and Earth

[EFC]

Hi everyone,

I decided to service my own alarm following some internet based instructions, and a crib sheet left from an engineer who previously serviced the system 18 months ago.

Whilst the alarm appears to be working perfectly, I bought a multimeter to test the battery and mains supply and noticed that I have 14.5V AC across the neutral and earth connections of the incoming mains cable? I think the reading recorded by the engineer 18 months ago was 0.3V or 0.8V AC but he has signed the paperwork stating everything was OK.

The local electrical wholesaler said I shouldn't be getting any reading and leant me another multimeter to confirm the reading - which also showed 14.5 V AC.

I bought a plug in socket tester in case any wiring was crossed but all readings are normal for every socket in the house. I have not had any electrical work done in my home for about 4 years?

Anyone any ideas what could be causing this reading? I would have thought that the reading would be 230-250V if the was a short or crossed wires on my mains circuit. I don't think it is to do with the alarm which runs on about 13.5 v DC.

l'm a bit concerned that an electrician will charge a fortune if he says he needs to check all my mains wiring. I feel I am fairly competent and would like to try and trace the fault myself given some informed advice before resorting to an electrician.

All comments and advice welcome!

 

[wingcoax]

If you do get 240v across neutral and earth then you have a problem, you should get that across live and neutral.

 

[EFC]

If you do get 240v across neutral and earth then you have a problem, you should get that across live and neutral.

Thanks but I kinda figured that one out myself - hence the reference to possible crossed wires (i.e. Live and earth possible mixed up at the spur) to get a high AC reading across E and N.

 

[Europlex]

Whilst the alarm appears to be working perfectly, I bought a multimeter to test the battery and mains supply and noticed that I have 14.5V AC across the neutral and earth connections of the incoming mains cable? I think the reading recorded by the engineer 18 months ago was 0.3V or 0.8V AC but he has signed the paperwork stating everything was OK.

The local electrical wholesaler said I shouldn't be getting any reading and leant me another multimeter to confirm the reading - which also showed 14.5 V AC.

I'm no electrician but this below is is part of standard instructions when servicing an alarm system (Never had your problem though) ( would need to call an electrician)

MAINS PHASE NEUTRAL TEST. AC voltage between Live
and Neutral.
This should measure between 220 - 250VAC.

MAINS PHASE EARTH TEST: AC voltage between Live and
Earth.
This should be the same as the previous reading.

MAINS NEUTRAL EARTH TEST: AC voltage between
Neutral and Earth.
This reading SHOULD NOT EXCEED 1.2VAC.