Bathroom extractor fan: what's needed?

[welland99]

I want an extractor fan in my bathroom that is controlled by a wall-mounted switch that will be located outside the bathroom. I haven't chosen the fan yet and I haven't decided if I will tackle the job myself or get somebody in. So, just researching what is needed.....
The fan will not have a timer or any kind of sensor, so purely controlled by the switch.

1) Can I use a double light switch in which one side is for the bathroom light and the other is for the fan?
2) I imagine that the fan will need a fused double pole isolator as well. Is that correct?
3) Where can the fused isolator go? Can it be high up on the wall inside the bathroom, near the fan?
4) Does the isolator only need to isolate the fan itself, or also the wall switch?

 

[Deleted member 26818]

What is your intended purpose for the isolator?

 

[Midwest]

I want an extractor fan in my bathroom that is controlled by a wall-mounted switch that will be located outside the bathroom. I haven't chosen the fan yet and I haven't decided if I will tackle the job myself or get somebody in. So, just researching what is needed.....
The fan will not have a timer or any kind of sensor, so purely controlled by the switch.

1) Can I use a double light switch in which one side is for the bathroom light and the other is for the fan?
2) I imagine that the fan will need a fused double pole isolator as well. Is that correct?
3) Where can the fused isolator go? Can it be high up on the wall inside the bathroom, near the fan?
4) Does the isolator only need to isolate the fan itself, or also the wall switch?

Think you would be best to employ the services of an electrician.

 

[Octopus]

Why do you want the fan? Where will the extracted air vent to?

 

[Leesparkykent]

As long as the lighting circuit has RCD protection then you could install the fan on a light switch to operate the fan. In your situation I would use a double pole switch for maintenance of the fan. If the manufactures instructions say that the fan needs to be on a 3A fuse then you could install something like the click mini grid system so you can fit 3 modules on a 1 gang box, one for the existing light, one for the fan and the other space for a fuse carrier. How are you proposing to pick the feed up for the fan as at the existing switch you may not have a neutral?

 

[welland99]

What is your intended purpose for the isolator?

Well, I only mentioned an isolator because I thought that the regulations might require it. Do the regulations say that an isolator is required in addition to the wall switch for operating the fan? If it is not required, then it would be a helpful simplification to ignore it.

 

[welland99]

Think you would be best to employ the services of an electrician.

I may well do that, but it is always handy to have knowledge of what is needed before talking to somebody about it.

 

[welland99]

Why do you want the fan?

The fan is to extract moist air during or after a bath or shower. I don't want it to come on every time somebody turns the light on.

Where will the extracted air vent to?

The air will be extracted to outside. I have not yet decided if it will go through a wall or through the ceiling and be ducted through the loft.

 

[welland99]

As long as the lighting circuit has RCD protection then you could install the fan on a light switch to operate the fan. In your situation I would use a double pole switch for maintenance of the fan. If the manufactures instructions say that the fan needs to be on a 3A fuse then you could install something like the click mini grid system so you can fit 3 modules on a 1 gang box, one for the existing light, one for the fan and the other space for a fuse carrier. How are you proposing to pick the feed up for the fan as at the existing switch you may not have a neutral?

The click mini grid system sounds good. I'll bear that in mind. If the fan manufacturer specifies a fuse in the circuit, I suppose that it doesn't matter if the fuse is in the switch (click mini grid system) or in the isolator. Is this correct?

Would the two switches in the click mini grid box share the same common live supply from the lighting circuit, or would they need to be separate?

I was thinking that the isolator would get the switched live from the wall switch, and the neutral direct from the lighting circuit. Then a two core cable would take the supply from the isolator to the fan.

 

[Leesparkykent]

The click mini grid system sounds good. I'll bear that in mind. If the fan manufacturer specifies a fuse in the circuit, I suppose that it doesn't matter if the fuse is in the switch (click mini grid system) or in the isolator. Is this correct? If you install it the way I mentioned using a double pole switch then the switch also acts as an isolator for maintenance purposes. The feed to the fan switch would pass through the 3A fuse first.

Would the two switches in the click mini grid box share the same common live supply from the lighting circuit, or would they need to be separate? If the new fan is fed off the same circuit which ideally should be the same circuit that feeds the existing bathroom lighting.

I was thinking that the isolator would get the switched live from the wall switch, and the neutral direct from the lighting circuit. Then a two core cable would take the supply from the isolator to the fan.You need to pick up the feed live,neutral and earth from the same circuit

comments in red above. without being rude I suggest you employ an electrician to do the job as from what you've put so far you don't seem to have the know how to carry out the job. Also being a bathroom the job could be notifiable under part P.

 

[Midwest]

Quote: 'I may well do that, but it is always handy to have knowledge of what is needed before talking to somebody about it'.

Seems to me your asking for a stage by stage process on how to install the fan, and you have no intention of employing a competent person. You should really ask yourself if it's worth endangering yourself, to save a few penny's. When my car needs servicing, I take it to a garage.

 

[leep82]

Could you not fit a sw fused spur in the loft? Your switch wire then becomes your supply to said spur take a neutral from the lighting circuit and then out of the load side to the fan? Fan then has a means of isolation and can be fused down if necessary without having to have anything on show ( other than the wall switch )

 

[Deleted member 26818]

Well, I only mentioned an isolator because I thought that the regulations might require it. Do the regulations say that an isolator is required in addition to the wall switch for operating the fan? If it is not required, then it would be a helpful simplification to ignore it.

No there is no particular requirement for an isolator the wiring Regulations.
Howver some Building Control Officers insist on an isolator being provided for maintenance and cleaning, especially if there is no window.
Many fans are turned on by switching on the light, and then over run for a set time after the light is switched off.
Such fans require a permanent live and a switched live. The switched live being provided from the light switch.
Not sure about the manufacturers' instructions for the fan you intend to install, but it may be they require both the lives to be fused, or just the permanent live?
The simplest method is to fuse both the fan and the light.
Disconnect the cable which feeds the light, and connect it into either a switched or non-switched Fused Connection Unit.
Take a cable from the FCU to the light fitting and reconnect.
Then connect a 3 core cable at the light fitting and take the Permanent live, Switched live, Neutral and Earth to the fan.
If isolation for just the fan is required, take the 3 core cable to a 3 pole switch and then feed the fan from the switch.

I believe it is possible to obtain a 3 pole switch with fuse?

 

[leep82]

In the past where ive used in line fans that have required a seperate switch, ive taken a feed to a switch fused connection unit. From this switch fused connection unit ive then taken a feed, from the load side to the switch. Returning from the switch i then have a permanant feed, providing the switch fused connection unit isnt turned off, and a switch wire. I find this the easiest way to do it as both permanent and switched feed to the fan can be fused down