Bathroom fan backwards

by **AndyY** » Tue Jan 06, 2009 12:38 pm

Hiya,
we have an extractor fan which is somehow wired up to the light switch in the bathroom... however we've only been able to control it using the isolator switch - think there is something back to front:

Isolator off, light off - fan off; switch isolator & the fan comes on.
Isolator off, light on - fan off; switch isolator the fan stays off until lights turned off.

After about ten mins with the light on the fan eventually goes off!!

The extractor is located a floor above the bathroom (the flat we live in is a bit upside down).

I'd appreciate any help you might be able to give or is the a case that something has gone in the xtractor?

Thanks
Andy

by **stoneyboy** » Wed Jan 07, 2009 6:12 pm

AndyY,
You need to check the wiring in the extractor - I suspect that the Live and switched live connections have been reversed.
end

by **AndyY** » Thu Jan 08, 2009 2:04 pm

Thanks stoneyboy - is there a easy way of telling which is which?

by **stoneyboy** » Thu Jan 08, 2009 6:33 pm

AndyY,
With a test meter meter yes - the cable to the L terminal should be permanently live (with the isolator on).
Suggest you turn off the circuit and swap the cables into the L and SL on the fan. You may need to find the instructions to confirm the markings.
end

by **Mr Fixit** » Thu Jan 15, 2009 10:24 pm

Most bathroom fans are powered off the lighting ciircuit and switched via the live return to the bathroom lamp holder.

The way you have described the problem, it could be that you are resetting the fan electronics each time you turn off the switched fused spur.

If you turn off the isolator (switched fused spur) and remove the cover of the fan. Do not touch any of the exposed cable cores or terminations.
You should be able to see an adjustable potentiometer (variable resistor) control. Turn it to minimum, replace cover, turn on the switched fused spur and then see how it performs using the light switch.

Do let us know how you have gone on.

Mr Fixit

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