Bathroom Extractor Fan - With Pull Cord, With Timer

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Hi. I intend to fit an extractor fan with timer in the bathroom ceiling, to work independently from the light, with a separate pull cord switch.

I've fitted extractor fans before, although not one with a timer, but I have a few questions to ensure it's done right -

1. The fan will be situated away from the shower and bath, although above the sink. Does it need to be a low voltage one because of this.

2. Because it will be a fan with a timer, therefore having a permanent live, I assume I will need a fan isolator switch. Does this have to be situated outside of the bathroom, and if so is it allowed in the loft space above the fan.

3. If I choose to have a fan without a timer, do I still have to have a fan isolator switch, or is it ok to just use a double pole pull cord.

4. I am taking the feed from a junction box in the loft space above, which feeds a light and smoke alarm. I assume it's usual to take both live wires (i.e. the normal live and the permanent live) from the same terminal in the junction box.

5. As the cable (3 core and earth) will run from the existing junction box in the loft, to the pull cord switch first, then to the fan isolator switch, then to the fan, (if that order is correct), is it ok to simply connect the permanent live to the input terminal in the pull cord switch. i.e. the permanent live will run from the junction box in the loft, to the input terminal on the pull cord, then to the fan isolator switch, then to the fan. So obviously when the pull cord is switched off, it doesn't affect the permanent live, so the timer on the fan will still operate.

This is such a great forum.
Help appreciated as always, thanks.

 

[stem]

1. The fan will be situated away from the shower and bath, although above the sink. Does it need to be a low voltage one because of this.

The fan needs to be suitably rated for the zone in which it is located. See here

http://images.google.co.uk/images?h...&sa=X&oi=image_result_group&resnum=1&ct=title

2. Because it will be a fan with a timer, therefore having a permanent live, I assume I will need a fan isolator switch. Does this have to be situated outside of the bathroom, and if so is it allowed in the loft space above the fan.

Check the zone of the switch for it's location. Usually they need to be situated outside the bathroom. It has to be adjacent for easy isolation for maintenance. In the loft it is not, nor is it easily accessible.

3. If I choose to have a fan without a timer, do I still have to have a fan isolator switch, or is it ok to just use a double pole pull cord.

Yes, but I think there are minimum contact gap requirements (3mm springs to mind maybe someone else will advise) Also it will need some indication flag/pilot light to show when it's off.

4. I am taking the feed from a junction box in the loft space above, which feeds a light and smoke alarm. I assume it's usual to take both live wires (i.e. the normal live and the permanent live) from the same terminal in the junction box.

Smoke alarm circuits are for smoke alarms only

5. As the cable (3 core and earth) will run from the existing junction box in the loft, to the pull cord switch first, then to the fan isolator switch, then to the fan, (if that order is correct), is it ok to simply connect the permanent live to the input terminal in the pull cord switch. i.e. the permanent live will run from the junction box in the loft, to the input terminal on the pull cord, then to the fan isolator switch, then to the fan. So obviously when the pull cord is switched off, it doesn't affect the permanent live, so the timer on the fan will still operate.

Sounds OK (except as 4 above) all 3 wires, perm live, switch live & neutral will need to be switched at the isolator.

 

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Thanks for your reply.
Seems straightforward enough.
Cheers.

 

[sparkyspike]

You may want to consider that using a pull-cord on a fan with a timer and independent of the light switch, you may not be able to tell whether the fan has been left on permanently or not. A neon on the fan would solve this.

Also, smoke alarms can be found on local lighting circuits.

 

[pbar]

You may want to consider that using a pull-cord on a fan with a timer and independent of the light switch, you may not be able to tell whether the fan has been left on permanently or not. A neon on the fan would solve this.

Also, smoke alarms can be found on local lighting circuits.

Yes, you're right, the smoke alarm is taken from a junction box which is for the upstairs lighting.

And I have seen some pull cord switches which have an on/off indicator on them.

 

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I think the hard part is getting the ducting outside somehow.
Unless I find a 6" tall human I can't see how I can get to the soffit to fit the vent.
What are the usual methods for this?

 

[stem]

Also, smoke alarms can be found on local lighting circuits.

"Can be found on" doesn't mean should be on. See info from "Kidde" one of the major suppliers of fire safety services below.

"The 17th Edition of the IEE Wiring Regulations (BS 7671:2008) takes effect in July. In a major change, it now requires circuits of safety services - such as hard-wired smoke and heat alarms - to be independent of other circuits and unaffected by, for example, “tripping-out” of other circuits. Now, smoke and heat alarms can no longer be powered from lighting circuits."

 

[pbar]

Also, smoke alarms can be found on local lighting circuits.

"Can be found on" doesn't mean should be on. See info from "Kidde" one of the major suppliers of fire safety services below.

"The 17th Edition of the IEE Wiring Regulations (BS 7671:2008) takes effect in July. In a major change, it now requires circuits of safety services - such as hard-wired smoke and heat alarms - to be independent of other circuits and unaffected by, for example, “tripping-out” of other circuits. Now, smoke and heat alarms can no longer be powered from lighting circuits."

That's for new smoke alarms thought isn't it? Mine (which was installed by a Part P electrician and approved by building control as part of an extension build) was fitted some time ago. They are all interconnected wirelessly and have battery backups.

 

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Due to not being able to extract through the soffit unfortunately, I think I am going to have to extract through the roof. How do you guys usually go about this? Is it possible to just remove a tile, and buy a replacement tile which has the ducting in place already, or are these made up on site, or something else?

 

[bsr]

Is it possible to just remove a tile, and buy a replacement tile which has the ducting in place already

Yes! Take a pic of your tiles with your mobile, and go to a builders merchant. They'll probably be able to get you a matching vent kit.

Otherwise, you could always remove a piece of soffit or fascia and get access through the soffit that way.

 

[sparkyspike]

For a cheap makeshift vent that looks discrete, you can cut a short length of 4" waste pipe diagonally to leave a semicircle at one end. Tap a square of lead over the top and slide under the tiles to cover the 4" hole underneath.

To get ducting down to a soffit you have normally lie on your front and get a faceful of insulation as you partly dislocate your shoulder to poke it down. At least that's how I do it.

 

[pbar]

Is it possible to just remove a tile, and buy a replacement tile which has the ducting in place already

Yes! Take a pic of your tiles with your mobile, and go to a builders merchant. They'll probably be able to get you a matching vent kit.

Otherwise, you could always remove a piece of soffit or fascia and get access through the soffit that way.

Magic! Yes, I have looked into what you said, and Sandtoft (who make my tiles, (I have the Sandtoft Calderdale one's) make a replacement tile which has a concealed vent and the ducting adapter underneath. So it's just a case of removing a tile near to the edge, I am hoping to reach from the ladders so no roof climbing, replace with the one with the concealed vent, cut a hole in the roofing felt and connect the pipe from the fan. Marvellous. What's not to love. Thanks.

 

[ban-all-sheds]

Don't forget the condensation trap.

 

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Don't forget the condensation trap.

Thanks for the heads up. I am hoping I wouldn't need one, as the ducting isn't going 'straight up' from the fan to the roof.