Fusing down of extractor fans

uksparks · May 8, 2015

Hi,

I have a question I would like to put to you to see who does what really.

The majority if not all manufacturers state something about the fan must be fused down to 3A...

Ok, scenario...

You have a bathroom, 6A light circuit, the light can either be switched at pull cord, light switch outside or the light fitting.

The customer says they want an extractor fan with Timer.

Option One
Do you just fit a fan in the ceiling / wall, and connect it off the light circuit straight to it and think nothing of it? This would be a permanent live supply and switched live.

Option Two
Do you fit a fan, and put a 3A fuse on the permanent live only? Leaving the switched live on 6A, also leaving the fan with the possibility of a blown fuse scenario but also having a live supply to it. You also fit a 3 pole fan isolator.

Option Three
Do you fit a fan, and put a 3A fuse on the permanent live supply to the light, then use that for the live for the fan, and the switched side of the light for the switched live etc. You also fit a 3 pole fan isolator.

Just to add to this
On top of these three options, lets say this is downstairs, no loft space etc, brick walls. You need to put a 3 pole isolator somewhere, where do you put it? Do you surface mount it in a box? Do you use a 3 pole pull switch on the ceiling? But hang on, where do you then put the 3A fuse? Do you not bother? Do you put in on the surface or ceiling?

Just wondering what others do as have been having this conversation with a couple of people. I also rang Manrose about this about putting a 3A fuse across the switched live too, they said, although preferable, it only really needs it on the permanent live.

onions1066 · May 19, 2015

It's my favourite hobby

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onions1066 · May 19, 2015

So if the motor stalled and caught fire. You had installed the fan against manufacturers instructions which supercede bs7671 . What would your valid reason be that you didn't fuse the fan down?

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grandfortune · May 19, 2015

This came about as there was a fire on a new build hotel in London, Insurance would not pay out as they proved the Electrical COntractor hadn;t fused the fan down to 3amps as the blades got caught and it burnt out.

not sure of the make but basically everyone started bringing out 3pole switches with fused unit built in, dont fuse down at your peril, Insurance company's love to find ****e like that to get out of paying up

Cheers
Grand

Jimmyb · May 19, 2015

I once got told, wot would u do if a house burnt down due to a faulty fan, even tho the 3amp fuse wudnt of made a difference you'll get the blame for not doing it

Leesparkykent · May 19, 2015

onions1066 said:
So if the motor stalled and caught fire. You had installed the fan against manufacturers instructions which supercede bs7671 . What would your valid reason be that you didn't fuse the fan down?

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Do you also fuse down the switch live? I install fans that don't state they need fusing down so I don't have to worry there!

Have you seen the reg change in the BYB regarding following manufactures instructions?

It has changed from:

"Good workmanship by competent persons or persons under their supervision and proper materials shall be used in the erection of the electrical installation. Electrical equipment shall be installed in accordance with the instructions provided by the manufacturer of the equipment."

To:

"Good workmanship by skilled (electrically) or instructed (electrically) persons and proper materials shall be used in the erection of the electrical installation. The installation of electrical equipment shall take account of manufacturers’ instructions."

onions1066 · May 19, 2015

But what i can't understand is why your not fusing down. Explain that part to me? ?

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onions1066 · May 19, 2015

To me it reads virtually the same. Best thing to do Is call the manufacturer and ask them. I know what they will say.

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uksparks · May 19, 2015

I always follow instructions, I just wondered what others do.

surely if it's a magnet type of motor, you know what do you call them? You know like a fish tank pump, so if the spindle is held still it makes no odds, it just won't spin.

onions1066 · May 20, 2015

I think what I'm trying to say is. At point of design these fans will of been tested to destruction to gain the relevant British standards they require to go to market. So at some point it has found that a 3 amp fuse is required to make it comply. So i can't see what the massive problem is fusing these fans down. In my eyes if you go down the triple pole isolator only it's for no other reason than to make the job easier for yourself. And uksparks my comment wasn't aimed at you or anyone in particular.

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Leesparkykent · May 20, 2015

onions1066 said:
I think what I'm trying to say is. At point of design these fans will of been tested to destruction to gain the relevant British standards they require to go to market. So at some point it has found that a 3 amp fuse is required to make it comply. So i can't see what the massive problem is fusing these fans down. In my eyes if you go down the triple pole isolator only it's for no other reason than to make the job easier for yourself. And uksparks my comment wasn't aimed at you or anyone in particular.

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not all manufactures state that their fans needs fusing down to 3amp. And if it did I would use one of these.

Resu · May 20, 2015

onions1066 said:
At point of design these fans will of been tested to destruction to gain the relevant British standards they require to go to market. So at some point it has found that a 3 amp fuse is required to make it comply.

Then they should fit a fuse within the fan!

Englishman · May 23, 2015

I'm another who never fuses down the fans. They're nearly always on a 6a breaker anyway and I really don't see the point in all honesty.

ackbarthestar · May 23, 2015

onions1066 said:
I think what I'm trying to say is. At point of design these fans will of been tested to destruction to gain the relevant British standards they require to go to market. So at some point it has found that a 3 amp fuse is required to make it comply. So i can't see what the massive problem is fusing these fans down. In my eyes if you go down the triple pole isolator only it's for no other reason than to make the job easier for yourself. And uksparks my comment wasn't aimed at you or anyone in particular.

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Yes sir, we'll supply you with your new car. Our manufacture's tests have made it clear that brakes would be necessary to comply with the current regulations. However, sir our policy is to leave it to the purchaser to find a fully competent registered part P automotive mechanic to supply the necessary braking system to make your new vehicle safe.

onions1066 · May 26, 2015

ackbarthestar said:
Yes sir, we'll supply you with your new car. Our manufacture's tests have made it clear that brakes would be necessary to comply with the current regulations. However, sir our policy is to leave it to the purchaser to find a fully competent registered part P automotive mechanic to supply the necessary braking system to make your new vehicle safe.

Sorry I'm missing your point?

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Dave OCD · May 26, 2015

If these fans [mostly under 20 watts ?] really need closely protecting why not use a 1 amp fuse to be on the safe side ? That ought to cover the worst starting current scenarios too. :smile5: