Low voltage behind one socket

[sammc007]

I have an MK K700WHI 200-250V Shaver Socket Outlet in a bedroom, which appeared to be faulty. The box has two T&E feeds, so I assume it’s on a ring of some kind. When I completely disconnected it and measured the voltage on the T&E cables in the box behind it, I measured 186V between live and neutral on one and 11.9V on the other, both AC of course. (I tested the socket with a "good" supply and it works fine).

Is there any common wiring fault that would explain these voltages? We moved into this house a few months ago and the socket never worked. I’m just now getting round to troubleshooting it.

Any help is appreciated.

 

[SLX]

First thing to do is establish if it is a ring or two radials. You’ll need to do some dead testing.

 

[Murdoch]

without proper test kit I doubt you'll get very far................

 

[Geoff1946]

Check first it's not on a lighting circuit. Shaver sockets often are.

 

[sammc007]

without proper test kit I doubt you'll get very far................

which I don't have.

 

[sammc007]

Check first it's not on a lighting circuit. Shaver sockets often are.

It's on a lighting circuit. There are ten 12V 50W halogen spots fed via transformers across two rooms plus a Vent Axa bathroom fan controller. These bulbs all burn at the expected brightness until I separate the two T&E feeds in the shaver socket box, then they +(and the fan) don't work at all. When I reconnect the two T&E feeds in the box and the lights are on, the same 186V shows between live and natural in the box. Really strange.

 

[UNG]

So if you don't have any test kit how are you measuring the 186v

 

[sammc007]

So if you don't have any test kit how are you measuring the 186v

I've got an HP digital multimeter, but no Megger etc. to try and find wiring faults.

 

[UNG]

The only HP digital multimeters I know of are designed for bench work so the voltage you are seeing is probably a ghost voltage

 

[Geoff1946]

Have you proved that your meter is OK ? (Remember the story of the railway man with the cracked hammer)

Digital multimeters, even good ones in 100% condition, can be really misleading largely because they are high impedance and as suggested above detect voltages which are induced within the wiring, i.e. ghost voltage, when on an unconnected wire.

You seem to have established that working lights are being supplied via the connections to the shaver socket, so it doesn't seem to make sense that the full mains voltage isn't there
Can you physically trace these cables, examining for damage junction boxes, etc?