I have an outdoor power socket which is not working. I have taken the back off and tested with a multimeter. It reads around 20V (not 240V). I've moved into this house fairly recently, so don't know the wiring. If a fuse had gone somewhere would my test show 20V? Could the cable be broken somewhere? (It is a proper armoured cable.)

Simon Field, December 2014

Morning Simon,
If the fuse has blown it should show no voltage.
but if you have a defective isolator switch it could give you a low reading.
Starting from basics, Check the settings on the multimeter.
Set to AC not DC
Voltage range at the first setting above 200 as it must be over 240.


If it still shows only 20V then the problem possibly lies either in with the internal supply feed, and/or switch.
A loss on one of the wires
Or in the main consumer unit.
Even if there are poor connections only allowing a trace current it should still read the same as the mains voltage.
Where the cable feeds out of the household consumer unit is it protected by an RCD or an old fashioned fuse.
Or is it plugged into a socket to connect it up?

THE FOLLOWING SUGGESTIONS SHOULD ONLY BE CARRIED OUT BY PERSONS COMPETENT IN WORKING WITH ELECTRICITY!

Either way the voltage should be checked at the point of origin first, at the main consumer unit and work down towards the socket.

If the main feed is OK, then the voltage,operation and connections of the isolator switch, that cuts of the power to the socket, should be checked next.

If that's OK, with the mains SWITCHED OFF disconnect the wire from the main supply, then with nothing plugged into the garden socket, check continuity between Pos & Neg, Pos & Earth, Neg & Earth at the mains end. There should be none.

Whilst still detached from the mains, connect the positive and neutral together, (Ensure the ends can't touch anything live) then check continuity at the socket end. It should read about 0.5 of an Ohm on the pos/neg terminals and nothing between pos or neg and earth.
If there is a high reading or a reading between the earth and either pos or neg then the cable is suspect.
If all of these check out, with the mains still switched off, reconnect the cab le to the switch or mains, ensuring correct polarity and making good, new connections.
Check all connections at the socket end and remake if necessary.
Switch on mains
Switch on socket isolator.
Check voltage at socket.
Would need to know the results before commenting further.
Hope it helps.
Good luck John

John, December 2014

No it is just an ordinary waterproofed socket. No switch or RCD protection on the unit.

Simon, December 2014

is it an rccd socket ?

gts, December 2014