[Closed] Quick (boring) electrical question - extractor fans :-/

I would doubt it is fused but it is very odd that it would die like that. Does it switch on on and off with the light or is it wired so it runs on for a period of time after the light is switched off?

Hmmm, it didn’t trip the house RCBO / RCD thingies either ..

Went from happily sucking grotty child smells to an eery silence..

I hate tractors now.

Johndoh - it’s triggered by the light switch but then stays on for ten mins after the light’s turned off (approx)

I hate tractors now

😃 very good

Hmm so my only outside guess (if it switched on and off immediately with the light switch) was going to be to suggest the motor stopping and starting in quick succession had worked a wire loose inside the fan. Is it a pull cord switch inside the bathroom? Perhaps pulling on that has worked a wire loose inside the ceiling rose?

It is a pull cord yep. Tbh I’m not entirely sure where it’s wired into as the wickes cowboys Installers did it very quickly

It will have a fused feed to it won't it? And the light switch is just a trigger for switching it on.

I would check the pull cord terminations first. Then check for voltage on the fan.

It will have a fused feed to it won’t it? And the light switch is just a trigger for switching it on.

Yeah good point - if it was wired to current regs it will need to have a fused switch which would ordinarily be situated outside the bathroom door.

Hmm, it was done Dec 2013 if that’s relevant - no switch anywhere for it. I just had a brief crawl about up there and wires appear to disappear straight into bathroom lights Rose thing

(I’ve checked ceiling rose and nothing was loose, likewise the pull cord switch)

(No reset or fuse on fan itself - just timer electronics. Does have voltage on terminals so can only assume the electronics have failed or the motor itself (can’t see it being viable trying to source a motor)

I don't know why and I probably don't want to investigate the wiring to find out, but our extractor fan gets confused if you put the light on in the loft while the bathroom lights are on & the fan is spinning.
For some reason it will refuse to restart later on.

If I nip into the loft & flick the isolator for the fan, then it all works again.

Maybe the constant flicking of the switch has cocked something up with the live switching of the fan?
I would be tempted to try flicking off the consumer unit fuse for your upstairs light for 5 mins with bathroom light off, putting it back on and seeing if that solves it.

No idea why it would, but killing power to our extractor (via the isolator) sorts it.....

^^ hmm odd.

Well electrics have been off and on quite a bit whilst I’ve tinkered and it’s made no difference. All connections seem fine and lots of lovely alternating currants arriving at the fan.

I think I need a new fan ... not expensive but a complete faff to fit unless I just use the existing vent/ piping

If you get a new one get one of these - get this model too, not the newer version as it is not meant to be as reliable.

My money is on Stumpy's switched live being "borrowed" from the loft light...
Definitley no pudding ,for a week!, for ropey's kids.

So... if I get a replacement is it likely to have the same electrical connections and be a like for like swap?

Could someone explain in (simple terms) how it’s likely this is fed from the ceiling rose? There’s three cores to the fan unit - I assume one is connected to light to trigger the fan and the other is the live/neutral for the fan supply?

(Oh and we don’t have a loft light, annoyingly)

(Despite appearances I’m not a complete electrical numpty but like to check my understanding!)

Could someone explain in (simple terms) how it’s likely this is fed from the ceiling rose? There’s three cores to the fan unit – I assume one is connected to light to trigger the fan and the other is the live/neutral for the fan supply?

You need a 'constantly live' live (for the run-on when the light is off), and a 'switched live'. And obviously a negative.

You need to identify which live is which in a safe fashion, then transfer them over to the new fan. The Manroses have the option to adjust the fan speed, so you would also need to work out how much is sufficient.

Worth swapping out flexi ducting for rigid wherever possible.

(More questions - wondering if the guy who re did our loft insulation killed fan by covering it? I’m guessing it’d get quite warm snuggled under 10” of rock wool stuff?!)

Thanks martinhutch - the ducting might have to stay unfortunately as it’s all squashed into an impossibly tight space right where the roof meets the bathroom ceiling.

Re regs - do you still need an isolator switch if the fan isn’t actually in the bathroom as mine is (ie in loft)

If it has a run-on function (so is permanently live with no way of isolating it), I believe the switch would be required, unless the manufacturer's instructions (for the new fan) stipulate something different. Best thing is to download the installation instructions for the fan you're trying to put in there and have a quick look.

(More questions – wondering if the guy who re did our loft insulation killed fan by covering it? I’m guessing it’d get quite warm snuggled under 10” of rock wool stuff?!)

Unlikely. Most fans are rated for direct contact with insulation because they are self cooling with all the air moving past.

So, the old fan did indeed have a run on facility but there appears to be no switch at all.

Most of these fans instructions say “The installation must have an omnipolar switch with a contact separation of at least 3mm. The circuit must be protected by either a 3 Amp fuse.“

So.. can I replace like for like safely or does need an isolating switch / fuse?

Sorry for all the questions ..

Having a fused switch would be safer, and you can isolate the fan to stop it going for ages when you get up in the night for a wee.

Obviously just plugging in the new one into the old wiring and accepting you'll have to isolate it from the consumer unit is more convenient, especially as the new wiring would mean the whole installation would have to be Part P compliant, and possibly be notifiable, depending on where you want the switch.

Isolator switch in the loft, next to the fan. FTW!
"Always been there mister."
Tbh, the person who installed it really should have done that.