My bathroom light is not working but the extractor fan via the same cord fitting is. I replaced the cord fitting and checked there's current running through both wires when it is turned on.

I then checked the transformer in the halway which controls power to the light and fan. I checked with a voltage screwdriver and it picks up voltage to both the fan wires when the light is switched on but only the brown wire on the light, not the blue wire.

I asume there's an issue with the transformer as, is it easy to fix? It looks like an old model so not sure I could get a replacement, it says 'vent axia selv 12' on the outside.


  • 1
    Maybe your lightbulb need replacing? Dec 6, 2016 at 16:44

1 Answer 1


SELV 12 means it is a 12-volt device.

Your "voltage screwdriver" is not suitable for testing low voltages like this.

The wiring should be as follows

enter image description here

Note this shows a main bathroom-light as well as a low-voltage light inside the fan unit.

Your pull-cord switch operates at 240VAC.

The Transformer does not supply power to the main bathroom-light. Only to the SELV light inside the fan-unit (where applicable).

The usual reason for lights not lighting is that the light-bulb needs replacing. You don't say whether you have replaced the bulb or tested it.

You can check the 12v connections using a more suitable voltage tester (with a 12V capability but safe for 240VAC)

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