Manrose inline extractor fan (with timer)

[Scubabob]

I have an inline fan installed in a bathroom, linked to the lights. All works fine, turn the lights on & the fan triggers. Turn the lights off & the timer runs as it should.

Now the problem. If you turn the kitchen under cabinet lights on it triggers the bathroom fan. It doesn't bring the bathroom lights on though, just the fan. If you then turn the under cabinet lights off the fan stops instantly (no timer overrun).

Just can't get my head round this. The under cabinet lights are LED on a electronic driver unit. The fan is a Manrose MFT unit..

Any ideas why the fan is triggering????

 

[SPECIAL LOCATION]

Sounds like something could be wired wrong...?

First step is back to basics, and dead test all the wiring..
verify their are no cross connections etc..

 

[Scubabob]

Nope, no crossed connections. Perm live, switched live and neutral all as normal. All works normal , inc timer overrun. Under cabinet lights triggers the fan but not the lights and doesn't trigger the overrun. Weird .

 

[Richard-the-Ninth]

As the fan starts when the kitchen LEDs are switched on, and stops when the kitchen LEDs are switched off (But the bathroom light stays off) I would suggest you change the LED driver for a differant brand (Same output voltage, but can be higher current) It may be possible to "Add a surpressor" but which one and what value.

 

[SPECIAL LOCATION]

Nope, no crossed connections. Perm live, switched live and neutral all as normal. All works normal , inc timer overrun. Under cabinet lights triggers the fan but not the lights and doesn't trigger the overrun. Weird .

No idea what you mean by "all as normal"?
Have you actually done ALL of the dead tests as per BS7671?

e.g. comprehensive continuity and insulation resistance tests on all relevant circuits?

 

[Scubabob]

Yes. All tests done. Never come across anything like it before. Even been on to Manrose Tech. They've never seen it before. They thought maybe a faulty timer board, being spiked. Interestingly, connected a new fan and still the same. Disconnected the switched live and switched the bathroom lights on, no fan operation. Turned the kitchen under cabinet lights on and bingo, the fan runs even with the switched live missing.

Next , going to look at the LED driver on the cabinet lights .

 

[Sensai]

Hi, it sounds like the 'permanent' live to the fan is coming via your kitchen lights hence the overun is not coming on when you switch them off as the fan has no power then. Voltmeter on the fan and try the lights in the kitchen. Does it register voltage when they are on and off?

 

[Scubabob]

Permanent live is there. The Bathroom lights work fine with the fan running with timer overrun even with the under cabinet lights off. Everything as normal. The problem comes when you turn on the cabinet lights. It triggers the bathroom fan. The permanent live and neutral are present, the switched live disconnected and the fan still triggers.

 

[Sharpend]

You need to measure some voltages to see what is going on.

 

[steptoe]

I think you need to do some digging on the neutrals,

 

[Sensai]

Check the permanent live Line cable for voltage. Have someone turn the kitchen lights on and off and see if it becomes present as you may find they are joined somewhere. I just worked on some bathroom downlights lights connected to a Manrose fan and when the lights were isolated I found the fans permanent live came from a socket in the loft then to the light switch before going back up to the fan. It's switched live was part of the light circuit so at the switch I had isolated the lighting but still had a live cable for the permanent live so had to find the source for that.

 

[Murdoch]

My money is on a loose connection.

 

[Mike P]

I would check polarity. Use earth as your reference and make sure you have 230v on Phase conductor and switch conductor and zero volts on neutral conductor. I had a similar fault with a customer where someone had looped the switch phase conductor through the tungsten lamp and then on to the next lamp causing low voltage and half power on lamps

 

[binky]

I think you need to do some digging on the neutrals,

Gets my vote! Borrowed neutral

 

[Scubabob]

Update. It would appear the LED driver on the under cabinet lights has a frequency that is triggering the fan.

 

[Richard-the-Ninth]

It would appear the LED driver on the under cabinet lights has a frequency that is triggering the fan.

Commonly known as interference.

How did you figure that out, and how are you going to resolve it?

And thanks for letting us know.

 

[roys]

Mesh screen round driver, ferrite on driver supply cable, new driver? come tell us

 

[runningpiglet]

Update. It would appear the LED driver on the under cabinet lights has a frequency that is triggering the fan.

Try disconnecting the cupboard lights and replacing temporarily with load of similar wattage and see if problem persists?