Scolmore Click 3amp isolator switch

[DetlefSchmitz]

I have always wondered why fusing only one of the live supplies to the fan is ok. If it needs it why not fuse both lives?

I'm sure someone else will answer this before I get there. The only possible justification for requiring a fuse is that the fan is an electrical motor and if it is stopped by a fault, then the current drawn can get much higher and possibly become a fire risk. As they don't know what the supply is fused at (could be 32A) they request that you do what they should have done internally and add a 3A fuse. This high current danger is not present on the switch live as it only drives a high value resistor.
Of course the assumption is that the 3A fuse will blow rather than allow enough current to start a fire. I doubt they have tested this in practice.
In other countries where the fuse is 16A, the fans just catch fire and thousands of homes there are destroyed every year.

 

[EFLImpudence]

I 'liked' the rest of your post, but:

Neverthless it would IMO be a brave installer who disregarded manufacturers instructions on protective device ratings, no matter how silly they are.

is a ridiculous thing to say; the logical conclusion of which is to blindly follow any inane instruction from any manufacturer.

 

[RandomGrinch]

This high current danger is not present on the switch live as it only drives a high value resistor

Yes, usually around 470k Ohms, in the boards I've seen. Together with resistors normal failure mode being open circuit, the risk through the switched live is small.

 

[Jelade Electrical]

First off, lets make it clear what you have. As supplied, the "fan isolator" switch and the fuse are completely independent. The "Lin" and "Lout" terminals relate to the fuse, while the L1, L2 and N terminals relate to the isolator. It is up to you to decide how, and indeed whether, to connect them together.

Many fan manufacturers, specify that their fans should be protected by 3A fuses, many people here think this is silly. BS7671 does not require manufacturers instructions to be strictly complied with, only taken into consideration. Neverthless it would IMO be a brave installer who disregarded manufacturers instructions on protective device ratings, no matter how silly they are.

The problem is that this thing has a 3 pole isolator, but only one fuse. That means attempting to use it as a direct replacement for a regular fan isolator will result in only one of the two feeds being fused. That IMO does not meaningfully comply with a requirement to protect the fan with a 3A fuse.

To solve that, we need to move the fuse back, so it comes before the light switch. The difficulty with this is it doesn't fit with the typical wiring layout. If you are wiring completely from scratch, the solution is to make the fuse/fan isolator the main loop-in point, but if you are trying to deal with existing wiring this is not easy to achieve.


View attachment 291559

It would be easier to just Fuse the light switch 1st, as your Diagram is what I came up 1st ...with whilst banging my head around a solution, as all the lighting within Bathroom will be protected by the fuse in the isolator at 3 amps which is not a big deal and will be less wiring if the switch was fused upstream then 3 core to a standard isolator via the supply side of Fuse...Note a switch should be issued by manufactures Click etc. as a bathroom 3amp switch with fuse incorporated

 

[JohnW2]

It would be easier to just ....

I think this issue was resolved well over 2 years ago!

 

[plugwash]

Note a switch should be issued by manufactures Click etc. as a bathroom 3amp switch with fuse incorporated

BTW the "fused fan isolator" is just switch module and a fuse module on a 3 module plate. So if you want to put the fuse with the switch you can still keep most of the components you have.

Click Mode Grid Front Plate

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Click Mode Grid Module

A range of modules that can be used with Click grid plates or as replacements in the Clicklight switch range to make bespoke switches.

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