Extractor fan wiring

[Jupiter01]

Can I get some advice with this please. It’s connected to an inline fan (no timer) in the attic and I’d rather rewire it here, than climb into the loft.

Let me explain the situation.

I have this fan switch outside the bath.


Here is the wiring:


The cables at the top are coming from the light and the cables at the bottom are going into the fan.

Brown is live, grey is switch live and I guess the black is neutral. I’ve tested L and SL using my two pole tester.

Here’s what is happening:
- when the fan switch is set to off the bath lights (downlights) switch on and off from its light switch. No issues
- when I switch the fan switch on, the lights come on (regardless of light switch position)
- if fan switch is on and I set the light switch to off, the lights get slightly dimmer and the fan is not as loud
- if fan switch is on and I switch the light switch to in, lights are fully operational, as is the fan.

Can you help me solve this puzzle please. Thanks in advance.

 

[pete01]

Sounds like the live and switched are joined in the fan.

If you take the brown out of the switch (going to the fan side) and put it in a wago that should do it....I think.

 

[Jupiter01]

Sounds like the live and switched are joined in the fan.

Would this be by design or a fault in how it’s wired into the fan?

 

[blup]

You only need the switch live to operate the fan, so the live in is redundant. Have a look at the rose or whatever feeds the down lights to be sure if the set up

 

[Murdochcat]

Has anything else electrical been changed or touched in the bathroom recently?

 

[pete01]

Either a standard fan has been used and live and switch live connected into the L terminal....or

A timer fan has been used and L and Ls have been linked,

Either way just remove the brown in the isolator switch/ load side.

 

[Jupiter01]

Has anything else electrical been changed or touched in the bathroom recently?

It's in my sisters house and they had a ceiling fan replaced with a in-line fan. Apparently, they had a similar issue previously too. She wasn't to precise about the issue previously but it sounded like the fan and light switch didn't work as they should.

 

[Jupiter01]

Either a standard fan has been used and live and switch live connected into the L terminal....or

A timer fan has been used and L and Ls have been linked,

Either way just remove the brown in the isolator switch/ load side.

It's definitely a standard fan. He showed me the box for the fan.
I will remove the live on the fan side and isolate. Presumably, the incoming live has no function either? I can leave in the switch terminal but interested to understand.

 

[pete01]

It's definitely a standard fan. He showed me the box for the fan.
I will remove the live on the fan side and isolate. Presumably, the incoming live has no function either? I can leave in the switch terminal but interested to understand.

The incoming brown is the permanent live (yes leave it connected) I'm assuming that when you switch the isolator on it joins the two lives together switching the lights on permanently.

I might be wrong but the first thing I'd try is removing that outgoing brown.

 

[pete01]

The incoming brown is the permanent live (yes leave it connected) I'm assuming that when you switch the isolator on it joins the two lives together switching the lights on permanently.

I might be wrong but the first thing I'd try is removing that outgoing brown.

Can you let me know if it works please I didn't sleep last night, worried about this

 

[Jupiter01]

Will report back shortly @pete01. Thanks again

 

[Jupiter01]

Thanks and all and especially @pete01. As suggested. I removed the live from the fan side and everything now works correctly.
Are we saying the live on the feed side is required or is that superflous here too? I don't plan to change it now as it is working! Just interested to understand.

 

[pete01]

Good I can sleep tonight now

The permanent live (brown) isn't needed here, but if you ever change the fan again you have the wiring in place to fit a timer fan.

 

[Jupiter01]

Good I can sleep tonight now

The permanent live (brown) isn't needed here, but if you ever change the fan again you have the wiring in place to fit a timer fan.

One more - before you head for your well earned nap - can I do something with this or the light switch to get an over-run on the fan? I appreciate that is what timer fans are for...

 

[pete01]

No you would need to change the fan.