Do batroom fan isolators need to be fused?

[sarahw]

I'm replacing my bathroom fan (timed one) with the same make and model model and the new one shows that a fuse is needed on te permanent live feed. The existing isolator switch is a 3 pole one outside the bathroom and doesn't have a fuse so I've looked for an isolating switch with a fuse and can't find one.

I'd like to follow the fan recommendations and fita fuse, so should I replace the fan isolating switch with a 3 pole fused spur switch or should I just stick with what I've got as it's how it was done by the electrician when the bathroom was replaced?

 

[ericmark]

Nearly everything needs some form of protection and bathroom fans normally need between 3A and 6A either fuse or MCB. In general MCB's are faster than fuses so to use a 3A fuse on a supply protected with a B6 MCB would be likely pointless since the MCB would likely trip first.

Most lights are protected by a 6A MCB so in most cases it does not require further fusing.

In theory if the manufacture says use 3A fuse that's what you should do. However the fuse fitted into 13A plugs has two preferred sizes 3A and 13A so it is likely any manufacture will ask for 3A fuse as that is the standard size and the 6B MCB will likely in real terms offer the same protection.

So personally if in consumer unit the supply to fan has a B6 MCB then I would not worry. However that is no what the Big Red Book says so I expect some one will tell me off.

But in real world to protect a bathroom fan from burning out if for example it became jammed it would need a lot less than 3A likely 500ma so I see no problem in using the 6A MCB which feeds the lights.

However if feed from ring main then we are looking at something completely different.

 

[ban-all-sheds]

I've looked for an isolating switch with a fuse and can't find one.

That's because they don't exist.

If you want to put a fuse in then you'll need to use a regular FCU, and replace the light switch with a double-pole one, with the light on one pole and the fan on the other, so that the light isn't also on the fan fuse.

If you use a switched FCU then obviously you can do away with the 3-pole isolator.

All this is notifiable if you're in England or Wales.

 

[ban-all-sheds]

However that is no what the Big Red Book says so I expect some one will tell me off.

 

[sarahw]

I've looked for an isolating switch with a fuse and can't find one.

That's because they don't exist.

If you want to put a fuse in then you'll need to use a regular FCU, and replace the light switch with a double-pole one, with the light on one pole and the fan on the other, so that the light isn't also on the fan fuse.

If you use a switched FCU then obviously you can do away with the 3-pole isolator.

All this is notifiable if you're in England or Wales.

I deiberately chose a fa of the same make/model so it was a trivial swapover. I haven't changed it yet and would rather getan electrician in to do this if it is, but it seems a bit ludicrous. Is this really notfiable?

 

[Hibbo]

This is the beauty of part-p; if you'd have just slammed the new fan in place of the old fan, you'd be no less safe and quite happy. However, because you have tried to do the right thing you now have to pay a small fortune to someone who has done the necessary courses and paid their money to a club (note how I didn't say 'to an electrician', as I really don't think that they are always one and the same), or pay a small fortune to you local council so that you can do a simple job in your own home.

Or you could just fit the fan.

 

[skenk]

I thought you didn't need to notify for direct replacement? Don't know why you're so bothered anyway Hibbo if you're in West Lothian.

It does show up a shortcoming of Part P though - you can replace the 20yr old fan yourself and be 'quite happy' but your existing wiring could be deadly

To the OP, ask yourself this (if you are fibbing and intend to DIY, not use a sparky)

a) Are you competent to be doing this kind of work?
b) When was the last time you had a wiring inspection & test (including the fan circuit) which said your household wiring was OK?

 

[GaryMo]

I thought you didn't need to notify for direct replacement?

You're correct - no notification is required.

Sarah, this doesn't mean that you shouldn't comply with Part P and install in accordance with the current wiring regulations(BS7671:2008, 17th Edition).
One such regulation is that the manufacturers instructions should be followed.

 

[ban-all-sheds]

Is this really notfiable?

Sorry - I meant the plan of replacing the switch with a DP one so that you only needed 1 FCU would be notifiable, as I assumed that your light switch is in the bathroom.

And I guess even then it might not be notifiable - look at the diagrams here: http://rapidshare.com/files/96697332/NL139supp.pdf

If the switch, and where you'd want to put the FCU, are outside the Zones then it would be non-notifiable.

If the current 3-pole isolator is outside the bathroom, and you want to put the two FCUs after it outside as well then that would not be notifiable.