Bathroom extractor timed overun

[cdel2005]

hi guys
I am changing my existing non timed extractor to a timed extractor
xpelair vx100t 12w/230v=0.05 amps

should i include a a 3amp FCU outside bathroom and a 3 pole fan isolator in loft near fan or will just just a 3 pole isolator be ok, if i put just a 3 pole fan isolator 10amp wouldnt this trip the 6amp mcb if a problem occured whereas a 3 amp FCU would blow instead of mcb?

the existing non timed fan is connected to a light pullcord

thanks

 

[ericmark]

Most fans have wiring which would need a milliamp fuse to protect, so the fuse only protects wiring, maybe a 1 amp fuse will rupture before a 6 amp MCB will trip, but would not like to lay money on that, so where running off lighting circuit no real point in a fuse, just an isolator so if it goes wrong you can switch it off and use the lights.

As to how to switch this is down to windows and if opening or not. So with a non opening window you must be able to switch it on independent of lights, you can have lights switch it on, but must also be another method, so looking at double pole light switches. To be frank with LED lights there is really no need to be able to switch on without lights, but the rules have not changed.

As to age of installation although regulations are not retrospective what is found is often when double glazing was fitted the opening window was removed to cut cost, at that time the fan should have been fitted to comply, so the room has never complied since that point, so you need a independent method to switch on the fan.

Timer in fan and momentary pull switch is likely the easiest method, there is also the PIR which could be ceiling mounted so easy to fit, but no point going through options when we don't know if the fan is simply because you want one, of because building regulations require it.

In spite of having an opening window the building inspector insisted a fan was fitted into mother wet room, because opening the window would allow people to look into the room from outside, as on ground floor, however he permitted it to be solely switched on with the lights. In real terms the isolator is switched off, and only switch on after having a shower to help with under floor heating to dry the floor.

So question is how do you want it switched? I would likely ignore the law in my own house and wire as I want, but would follow the law in some one else's house or where letting the house out.

 

[cdel2005]

thanks for your reply eric

i was just unsure wheather to use a 3 pole fan isolated being 10amp or 3 amp fcu or both
i.e if a problem occured with fan fuse blowing at 3amp would be better than mcb tripping at 6amp?
wouldnt it be safer,i also wanted to install same as manufacturers instructions but was a bit unsure.

 

[EFLImpudence]

i was just unsure wheather to use a 3 pole fan isolated being 10amp or 3 amp fcu or both

As neither is really required, it is up to you.

i.e if a problem occured with fan fuse blowing at 3amp would be better than mcb tripping at 6amp?

Probably not, it doesn't work like that.

wouldnt it be safer,i also wanted to install same as manufacturers instructions but was a bit unsure.

If you want to do that then you have no choice.
The fuse is usually stated as 3A. The diagram is odd in not showing this.

The Building Regulation just calls for the provision of adequate ventalation.
How that is achieved is down to personal interpretation.

 

[cdel2005]

EFL you say non is really required
dont you think it would be better to isolate with remote switch for maintenance purposes/faults?

1 light pullcord/ceiling rose straight to fan
2 light pullcord/ceiling rose -3amp fcu -fan with remote 3 pole isolator (diagram)
3 light pullocord/ceiling rose -3 pole isolator -fan

take your pick?

 

[winston1]

thanks for your reply eric

i was just unsure wheather to use a 3 pole fan isolated being 10amp or 3 amp fcu or both
i.e if a problem occured with fan fuse blowing at 3amp would be better than mcb tripping at 6amp?
wouldnt it be safer,i also wanted to install same as manufacturers instructions but was a bit unsure.

The 3 amp fuse will not discriminate against a 6 amp MCB. Most likely the MCB would go first.
Manufacturers instructions are for guidance and don't have to be followed especially if they are wrong as they clearly are here. Think what happens when they sell this fan in Europe where FCUs are not available or compliant.

 

[EFLImpudence]

EFL you say non is really required
dont you think it would be better to isolate with remote switch for maintenance purposes/faults?

Yes, that's why they are fitted, but as they are not required by a regulation, then there are no rules for fitting them other than general safety ones.

 

[ban-all-sheds]

As to how to switch this is down to windows and if opening or not. So with a non opening window you must be able to switch it on independent of lights, you can have lights switch it on, but must also be another method, so looking at double pole light switches.

FGS, Eric - not again. Are you ever going to stop posting this nonsense?

To be frank with LED lights there is really no need to be able to switch on without lights, but the rules have not changed.

And those rules are....?

So question is how do you want it switched? I would likely ignore the law in my own house and wire as I want, but would follow the law in some one else's house or where letting the house out.

Which law is that, Eric, and what does it require?

 

[ericmark]

Part F1 Table 1.5 Controls for ventilation devices
Mechanical Intermittent extract
etc etc
For a room with no openable window etc 15 minute over run.
In a room with no natural light, the fans could be controlled by the operation of the main room light switch.

So that clearly means if it has natural light, you can't control it with the light switch. Page 18. BR_PDF_ADF_2006

 

[JohnW2]

Part F1 Table 1.5 Controls for ventilation devices
Mechanical Intermittent extract etc etc
For a room with no openable window etc 15 minute over run. In a room with no natural light, the fans could be controlled by the operation of the main room light switch. So that clearly means if it has natural light, you can't control it with the light switch. Page 18. BR_PDF_ADF_2006

Yet again, you are quoting from the guidance of an Approved Document and making it sound as if it were Law, or 'requirements'.

Just as with Part P, Part F says virtually nothing, and mentions no detail. Part F1 (1) merely says:

There shall be adequate means of ventilation provided for people in the building

F1 (2) then goes on to say that mechanical means of ventilation should be installed so as to comply with F1 (1) (as above) - and that is the entirety of Part F1.

Kind Regards, John

 

[EFLImpudence]

Eric -
You do realise that the only legal bits of Approved Documents are the shaded green areas?

There is a newer 2010 ADF which states on page 15:

 

[ban-all-sheds]

Part F1 Table 1.5 Controls for ventilation devices
Mechanical Intermittent extract
etc etc
For a room with no openable window etc 15 minute over run.
In a room with no natural light, the fans could be controlled by the operation of the main room light switch.

So that clearly means if it has natural light, you can't control it with the light switch. Page 18. BR_PDF_ADF_2006

Yet again, you are quoting from the guidance of an Approved Document and making it sound as if it were Law, or 'requirements'.

And even if that was the law, "In a room with no natural light, the fans could be controlled by the operation of the main room light switch" would not mean that if the room had natural light the fan could not be controlled in the same way.

 

[EFLImpudence]

I am intrigued that someone thinks Britain such a police state that it could actually be illegal, and so punishable in the courts, for a person to switch off a fan too early.

The Building Regulation (the law) states that "there shall be adequate means of ventilation provided for people in the building".

This is presumably only applicable when Building Control is involved.
The occupant can then do whatever he wants; wire them however he wants, or - cover all ventilation methods in duct tape should he so wish.

 

[JohnW2]

I am intrigued that someone thinks Britain such a police state that it could actually be illegal, and so punishable in the courts, for a person to switch off a fan too early.

Quite so. Indeed, if it were such a state, then I imagine that it would be equally illegal, and equally punishable in the courts, or a person not to open an openable window in a bathroom! ... and equally daft!

Kind Regards, John