Light in extractor fan popping and tripping MCB

[feno3000]

Hi

Lots of topics on extractor fans and problems but cant find one with the exact problem I have.

Bought a cheaper timed extractor fan with light from wickes and had it installed, worked fine for the first 5-6 months. When the shower gets steamy there is a loud pop from the light fitting (not the fan unit in the loft space) and the MCB is tripped (which can be switched back on). The fan instructions say the light fitting is double shielded so doesnt have a ground but requires a certain amount of air flow past it, I assume to stop the moisture build up and it popping.
The ducting in the roof space is only 2 metres long and is in a straight line so I dont see why air flow should be a problem. I no longer have the receipt for it.

Does this sound like a faulty product(cheap) or a more serious issue with the wiring. we have an isolator switch outside the room and have no reason to doubt the work of the electrician who is a friend and been in the trade for quite some time, I dont think he would do a shoddy job for me.

any suggestions to test what the issue might be and would wickes accept that it is a faulty unit?


thank for your help.

 

[ban-all-sheds]

The ducting in the roof space is only 2 metres long and is in a straight line so I dont see why air flow should be a problem.

It's recently started to get cold, hasn't it.

Do you have a condensation trap in the ducting in the roof space?

If not then it's quite possible, and consistent with your description, that water is running down the ducting into the unit.

 

[feno3000]

There is no condensation trap.
the set up is the light in the ceiling and then about a meter of ducting then the fan unit and then another meter of ducting to the outside vent.
Where and how would I set up a condensation trap? also would wrapping insulation around the ducts prevent the rapid cooling of the condensation in the ducts.

Also when you say unit do you mean the actual fan or the light housing?

thanks for your reply

 

[JohnD]

wrapping the duct in loft insulation will help to keep it warm and prevent condensation. Also run the fan for 20 minutes or so after the steam appears to have gone, to help dry out the duct.

 

[riveralt]

It could one or several of these:

As BAS say water is running back down the pipe or someway getting into the wiring and shorting the circuit.

You have a loose connection at either the wiring terminal of the lamp or the fan, the isolator unit or the ceiling rose where it draws its power from.

You have been unlucky with a bad set of bulbs - it does happen!

The unit itself is broken somewhere - in which case take it back to Wickes - as long as you can show it came from them they will normally exchange without a receipt.

 

[feno3000]

the timer on the fan is set to 3 minutes at the moment, i'll adjust the timer up, ill get the ducting off tonight (just found some cable ties at work)