Bathroom fan. Light won't go off!

[clarkies]

Hi,

When we moved into our house, the fan in the bathroom did not work, so I decided to replace it. I ordered exactly the same one again to make it an easier fit and then went ahead to install it.

I have tested the 3 cables. There is one that become live when the pull cord for the light switch is used (switched live), one that is live all the time (permanent live) and another one which I assume is the neutral, as it isn't live. LOL

Anyway, I have wired it as per the instructions, but the bathroom light stays on, no matter what I do with the pull switch. The amount of light does seem to change slightly depending on whether it is on or off, but it stays on.

I have re-checked the wires in the fan and they are all fine, I have checked the light, and all the permanent lives are seperate in a connector block..........so somehow I guess the light is getting the live from the fan?

Or could it be something else?

Thanks

 

[ban-all-sheds]

I have tested the 3 cables.

With what?

There is one that become live when the pull cord for the light switch is used (switched live), one that is live all the time (permanent live) and another one which I assume is the neutral, as it isn't live. LOL

You shouldn't assume.

Did you measure the voltage between that one and earth, and between that one and the other two?

Anyway, I have wired it as per the instructions, but the bathroom light stays on, no matter what I do with the pull switch. The amount of light does seem to change slightly depending on whether it is on or off, but it stays on.

What happens if you disconnect the fan? Or just switch it off at the 3-pole fan isolator you should have?

I have re-checked the wires in the fan and they are all fine,

How was the old fan connected?

 

[clarkies]

I have tested the 3 cables with a simple electrical screwdriver. One comes on and off with the light switch which I thought was the SL, the other is live all the time which I thought was the permanent live and the other is never live.

I have wired it exactly as it was before.

When the fan is disconnected the light works as normal.

Thanks

 

[ban-all-sheds]

Throw the screwdriver away and buy a proper multimeter.

Does the fan stop after the overrun period? Does the light stay on after that point?

If you remove the bulb does the fan still work?

 

[clarkies]

Hi,

Thanks for your help so far its really appreciated.

Right, here's the update. When all the wires are connected as I think they should be..........

1. The fan stays on permanently and doesn't go off
2. The light stays on permanently and doesn't go off
3. When I switch the isolation switch they both go off
4. When I pull the pull cord, the fan goes off but the light stays on

When the pull cord is in the normal off position, the fan is running, when its in the on position the fan is off? I think thats the right way round.

Thanks

 

[DIYDANDY]

Swap the live and SL around and see what happens.

 

[clarkies]

Hi,

Its exactly the same when I swap them round. With the pull cord in the off position the light is on and the fan is running.

With the pull cord in the on position the fan goes off and the light stays on.

Thanks

 

[DIYDANDY]

Hi,

Its exactly the same when I swap them round. With the pull cord in the off position the light is on and the fan is running.

With the pull cord in the on position the fan goes off and the light stays on.

Thanks

Pictures of everything please.

And get rid of that screwdriver tester.

 

[clarkies]

what would you like pictures of?

Thanks

 

[ban-all-sheds]

Have you actually traced the wiring from the fan, back through the isolator and back to the light switch and light itself?

It sounds as though you don't have anything like what you think you do, particularly if turning off the fan isolator kills the light.

Does the light have a normal ceiling rose, or a 4-terminal JB next to it?

It might be quicker just to get some 3-core & earth cable and start again, run SL/L/N from the rose to the isolator switch to the fan, disconnecting all the old mess as you go.....

 

[electronicsuk]

Although unlikely, it could of course be a faulty fan.

Why not take the permanent live out of the equation completely for a minute? Isolate it in a terminal block, and wire only switched live and neutral to the fan. Link the L and SL terminals at the fan with a short length of wire.

If wired as above, your light fitting should operate as normal, and the fan should run when the light is on, turning straight off with the light. The timer function will do nothing.

If that turns out to be the case, you could them remove the L-SL link and see how the fan behaves. If an internal fault is linking the two terminals then the fan will still work, which of course it shouldn't without the switched live.

Oh, your lighting in the bathroom doesn't happen to be low energy CFLs or LEDs, does it?