240v between socket screw and radiator

[JohnD]

Hi all, got a shock when turning on the light and leaning against the radiator at same time. Realised I touched the socket screw first

When you say "socket screw" do you mean "light switch screw?"

 

[FrodoOne]

It could be as simple as the earth being absent from the lighting circuit and your meter being very sensitive/high impedance. Upload some photos, for a decent opinions.


As above, though just a slim chance that the 240v is from the radiator - check for voltage between switch screws, and 13 amp socket screws.

The above almost covers the tests required to determine what the "fault" actually is.


Purchase (or borrow) a cheap low impedance analog multi-meter.
(or, Shunt a high impedance digital multimeter with a 10,000 Ohms resistor.)

Use this to test for voltage between
1. the screw and a "good" Earth,
(which should be available at the Earth pin of a 3-Pin Socket-outlet - or any Earthed metal object plugged into such a socket. (e.g. A toaster, iron etc.)
2. the metal radiator and the above-mentioned Earth.
3. the screw and the metal radiator.

All should read (almost) Zero.

If 1 reads "High", the fault is in the household Earthing to the "box"
If 2 reads "High", the fault is an incorrect electrical connection to the radiator piping.