Switch fuse for ventilation fan with timer

[jcp]

I am installing two ventilation fans with timers in a RCD protected lighting circuit (5A MCB) covering 3 rooms (bathroom, toilet, utility room).

The fans are an inline Manrose MF100T for the refitted bathroom; and a wall mounted Manrose XF100T in the new downstairs toilet. A sparky told me I needed 3 pole isolating switches for each fan, but the manufacturers instructions say switch fuse units are also needed.

I didn’t see how one fuse unit could cover the constant and switched live feeds, but found circuit diagrams in the diynot.com wiki section under “fuse for ventilation fan with timer”. The best circuit seems to be that at the end of article, using a two pole switch fuse and a double pole switch. However, it seems to be dated 24/04/07: is it still compliant with the 2018 regs?

For the online fan, presumably I can mount the switch fuse beside the fan in the loft. The wall mounted fan in the downstairs toilet is mounted at ceiling level above the WC - with the small wash basin at the other end of the room (1.6 metres away). Can I mount the switch fuse above the WC - alongside the fan? It would involve considerable wiring and drilling to mount it outside the room.

I would be grateful for some advice

 

[Taylortwocities]

No point having switched fuse. The lighting circuit is protected by the MCB. That will trip before a fuse will blow.

Are you certain your MCB is 5 amps?

 

[jcp]

Thanks for that, and no - The MCB is probably 6A. I was away from the house when I wrote my post, and rather guessed what it was - (I’ve been turning it on and off for several days now, and I know it is one of 3 or 4 lighting circuits with lower ratings than adjacent socket circuits). I was going to check this today!

However, there is already a shaver socket in the bathroom without a switch fuse. Is that still OK?

And can I put the 3-pole switch next to the extractor fan above the WC in the Toilet?

Meanwhile, thanks again - I can forget the switch fuse.

 

[Taylortwocities]

Shaver point fine as it is.

Most people have them outside but
3-pole switch is ok inside bathroom providing it is not inside a bathroom zone.
https://electrical.theiet.org/media/1450/section-701.pdf

 

[jcp]

Thanks again for your help - and yes it’s a 6A MCB.

For the bathroom, I assume it is OK to mount the fan and 3 pole switch side by side in the boarded loft above the bathroom ceiling.

For the downstairs toilet of 0.8x1.8m (not 1.6 said before), I assume the bathroom zones would apply. Few zone drawings include WCs though some do show the area above as zone 2, so presumably it’s OK to mount my 3 pole switch alongside the fan, approximately 1.9m up, in the sloping edge to the ceiling above the low level WC. As I said before, the hand wash basin is about 1.6m away at the other end of the room.

I would be grateful if you could confirm these positions comply with the zones.

 

[flameport]

For the downstairs toilet of 0.8x1.8m (not 1.6 said before), I assume the bathroom zones would apply.

Bathroom zones apply to rooms with a bath or shower. Zones are as shown in the link provided previously.
Many diagrams found elsewhere are wrong, there are no zones around toilets, basins, bidets or any other items found in bathrooms.

If a room doesn't contain a bath or a shower, there are no zones.

 

[jcp]

Thank you, thank you, thank you.

That is exactly what I thought - but most published diagrams show zones around basins (600mm splash zones, or jet cleaning zones), and I feared the zones were being applied more widely than specifically listed in the regs - by a process of analogy and as good practice.

I can put my 3 pole switches in safe and convenient locations.

Thanks again

 

[Taylortwocities]

That is exactly what I thought - but most published diagrams show zones around basins

Most published diagrams are either wrong, or carried over from a time in history when there were different zones. The WIRING MATTERS article and ratings are correct. It had better be, it’s produced by the IET who write BS7671 the Wiring Regulations!

 

[JohnW2]

Most published diagrams are either wrong, or carried over from a time in history when there were different zones. The WIRING MATTERS article and ratings are correct. It had better be, it’s produced by the IET who write BS7671 the Wiring Regulations!

That's very true in this case (bathroom zones).

However, as a generalisation, I think your statement probably deserves a little qualification. The IET also publish the OSG and, whilst I doubt that there is anything in it which would be non-compliant with BS7671. there are quite a lot of 'guidelines' in it (the clue is in the "G" of "OSG") which many people seem to think (incorrectly) are actually requirements of BS7671.

Kind Regards, John

 

[Taylortwocities]

That's very true in this case (bathroom zones).

However, as a generalisation, I think your statement probably deserves a little qualification. The IET also publish the OSG and, whilst I doubt that there is anything in it which would be non-compliant with BS7671. there are quite a lot of 'guidelines' in it (the clue is in the "G" of "OSG") which many people seem to think (incorrectly) are actually requirements of BS7671.

Kind Regards, John

Indeed. Where a REGULATION applies in the OSG, the IET helpfully notes the regulation number.

 

[JohnW2]

Indeed. Where a REGULATION applies in the OSG, the IET helpfully notes the regulation number.

It does, so the absence of a regulation number should get our notice. However, it's only too easy for some (probably including ourselves) to forget about that and to think that some of the guidance it contains actually represent regulations/requirements.

I'm sure that some of the widespread 'myths'/misunderstandings about the regulations result from that.

Kind Regards, John