Bathroom fan

15 Sep 2006
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United Kingdom
Just installed a timed bathroom fan - works a treat.
Fan has low voltage light bulb and is wired up from a loop taken from the light circuit via a fused isolator switch in airing cupboard.
However instructions state fan can be switched on via the light switch. Tried this and again it works.
Problem - If I turn fan off with isolation switch, when bathroom lights are on then low voltage bulb in fan remains on. What have I done wrong. Is the fan circuit gaining current from the light circuit?
This does not happen when unit has separate pull cord switch, it only happens when I use try ad combine pull cord from light together with fan circuit.
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If you think about it you have supplied the permanent live and neutral from the fused spur, then supplied the switched live from a different part of the circuit that doesn't come from the fused spur.
Did the fan come with an instruction leaflet with wiring diagrams, most do?
Also please note, if you live in England/Wales this work is notifiable to LABC under part P of the building regs.
IIRC, the unit has connections for the fan & an independent connection to the lamp. The lamp is wired from the bathroom lighting circuit so as to come on with the rest of the bathroom lights. The fan part is wired from the same circuit through a TP isolator (Loop, switched live & neutral). This means the lamp will always be on when the bathroom switch is on.

You must have wired the lamp independently to the fan - that is why it it staying on when the fan part is isolated.

In any case, you said the fan was wired from the lighting loop. If this is the same as the circuit feeding the bathroom lights, then why should it matter if the fan is "gaining current from the lighting circuit"?

I suggest you get a qualified electrician to at least check that what you have done is correct. It sounds as if you don't quite understand what you have done.
Spark123 said:
Also please note, if you live in England/Wales this work is notifiable to LABC under part P of the building regs.

Good point. When undertaking major rewiring of an existing house, that work being notifiable to LABC, is it a legal requirement that a bathroom fan is installed (even where the room has a window and fanlight)?

Is it also mandatory to fit the required number of "low energy" lamps to the old property? In our case - a 3 bed semi, I believe 3 lamps are required. I understand they must be of a type that cannot be fitted with normal bulbs.

But is it mandatory to fit them and a fan to an old house?

I have had so many differing answers.
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Unless the work is classified as a renovation then no, new regulations do not have to be stuck to, but it is always a good idea because they are there for a reason.

Regarding the low energy lamps - its better to fit those throughout the house anyway, saves you cash, they last longer and it's better for the environment.

No, I do not believe it is classed as a renovation. The property was habitable and we are merely updating it - new kitchen, new bathroom, new wiring, new central heating. Nothing major, you understand! :)

But the LABC appointed electrical inspector, on his first fix inspection, told us that we had to fit these things.

The fittings are, in fact, much more expensive than those with ES bulb fittings, and are not available in a wide range of attractive designs for domestic use. B&Q and others do not supply them. Come to that, the big sheds don't even supply Part P compliant downlighters! We have bought compliant downlighters for the ground floor, and are therefore among a tiny number of people who have "safe" houses.

The ODPM finds it very easy to generate new laws without concern for the impact they have on ordinary people on a tight budget. It is clear that smoke penetration to the first floor of our property will be via the adjacent staircase before any finds its way through the ceiling, floorboards and carpet in the bedrooms above!

Because it makes sense to use low energy lights, we fitted one in the ground floor cloakroom, with a relatively expensive low energy fluorescent bulb. But this does not satisfy the law. Crazy, really, because we would not have a good reason to swap it for a more energu hungry tungsten bulb.

And, as for the bathroom fan, we would open the fanlight to more effectively ventilate the room. Energy will be used to fit the fan and operate it. It makes everything more difficult. I think Mr Prescott had a lot of friends in the electrical trades and businesses!


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