"crb" wrote in message
...

Checked all the wires for 240V a/c - nothing.

Interesting. How did you measure the 240v - between what and what?

Try measuring again between each wire in turn and a known good earth,
both with the CB engaged and tripped.


Interesting thought - however I can't test with the CB engaged because it
always trips.
For those reading this, please note that the fault manifests with no light
fitting attached and no switch attached.
Just bare wires out of the wall, and the two cables (power and switch)
clearly seperated.
So it cannot be a fault in the light fitting or switch.
The fault is inwards of the power cable coming from the rest of the
downstairs lighting circuit.

--
No plan survives contact with the enemy.
[Not even bunny]

Helmuth von Moltke the Elder

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