Bathroom fan: do UK regs require connecting via lighting circuit?

[MisterProzilla]

Hi,

I've just had some electrical work completed in the bathroom; I've recently refurbished the bathroom, replacing the old electric shower with a mains/mixer. I had bought an inline fan and a separate humidistat/run-on timer module with the idea that it could be installed using the old electrical shower wiring; my intention was that the wiring would go into the humidistat then onto the fan, so it's always live (with an isolator if needed), detecting moisture and turning on as needed without needing to switch it on manually via the lights or a separate pull switch.
Instead the electrician has installed it on the lighting circuit, saying that regulations require bathroom vent fans to be wired via the lights. I can't find any info about this -the humidistat is now effectively useless as I have to turn on the lights when I want the fan to run. Does anyone know of these regs and can you point me to them?

I'm in the UK by the way!

Thanks for reading

 

[brianmoooore]

Are you sure it's wired as you say? I would have connected it so that it runs all the time the light is on, plus an 'off' delay afterwards, or when the humidistat is on with the light off.

 

[MisterProzilla]

Are you sure it's wired as you say? I would have connected it so that it runs all the time the light is on, plus an 'off' delay afterwards, or when the humidistat is on with the light off.

Wired the way it is currently, it does work as you say - only when the light is on (and the humidistat module has a run-on timer so it does have the delay). I know a lot of people wire them that way, but I wanted to avoid that so I didn't have to switch the lights on all the time (and didn't have to rely on the kids doing it as well). I would have liked it to have detected moisture and turn the fan on even when the lights were off.

 

[DPG]

Wired the way it is currently, it does work as you say - only when the light is on (and the humidistat module has a run-on timer so it does have the delay). I know a lot of people wire them that way, but I wanted to avoid that so I didn't have to switch the lights on all the time (and didn't have to rely on the kids doing it as well). I would have liked it to have detected moisture and turn the fan on even when the lights were off.

I'm with you. I don't like fans that only work when the light is on. Whether the fan is running or not should not be determined by the light switch. 9 times out of 10 the light is not necessary during BST months.

 

[brianmoooore]

Read what I wrote again. I wrote OR when the humidistat..... The fan should run on the humidistat independently of whether the light is on or off.

 

[brianmoooore]

Whether the fan is running or not should not be determined by the light switch. 9 times out of 10 the light is not necessary during BST months.

That assumes the room has a window. I only wire the fan to the light switch if the room is windowless. If there's a window, the fan gets its own switch with a neon or LED indicator.

 

[DPG]

That assumes the room has a window. I only wire the fan to the light switch if the room is windowless. If there's a window, the fan gets its own switch with a neon or LED indicator.

Yes, I should have said in a bathroom with a window, sorry.

 

[davesparks]

No there is no regulation requiring bathroom extract fans to be supplied by a lighting circuit however it is normal for them to be.

There are some rules about the extract fans being wired so that they come on when the lights are on, this is easiest achieved by having the extract supplied by the lighting circuit.

An old electric shower supply is unlikely to be suitable for supplying an extract fan without modification.

If the fan incorporates a humidistat then it should have been wired with a permanently live supply so that the humidistat can operate, this can be done from the lighting circuit.

 

[Electro-tech]

Does this ventilation work come under Document F Now?

 

[brianmoooore]

Does this ventilation work come under Document F Now?

As far as I know, it always has, but of course Document F changes over time.
Current regs, for a refurb of an existing bathroom, are that if there was no fan before, then there's no obligation to fit one. If there was one there before, it needs to be retained or replaced by one at least as effective.

 

[Dustydazzler]

Most times I connect the fan with the light , but with a lot of posh bathrooms / en-suites I am doing they have dimmers and multiple switching for sets of lights.
So I then lean toward a hard wired fan with either a built in PIR or built in humidistat

 

[DPG]

Most times I connect the fan with the light , but with a lot of posh bathrooms / en-suites I am doing they have dimmers and multiple switching for sets of lights.
So I then lean toward a hard wired fan with either a built in PIR or built in humidistat

Trouble with the PIR method is the fan will kick in every time someone goes for a wee. Wasteful, and also unnecessary wear and tear on the fan.

 

[Dustydazzler]

Trouble with the PIR method is the fan will kick in every time someone goes for a wee. Wasteful, and also unnecessary wear and tear on the fan.

I agree but I offer both options and seem people want the PIR option, they pay the money they make the choice.

Also in reality a PIR fan is only like £90 so if it needs replacing in 5 years its nothing really when you think the about it

 

[DPG]

I agree but I offer both options and seem people want the PIR option, they pay the money they make the choice.

Also in reality a PIR fan is only like £90 so if it needs replacing in 5 years its nothing really when you think the about it

Yeah I'm probably being picky. It's just one of the things that bugs me bathroom fans.

 

[Dustydazzler]

Yeah I'm probably being picky. It's just one of the things that bugs me bathroom fans.

I don't have one in my bathroom , I just open the window