Scolmore Click 3amp isolator switch
- Thread starter banchee
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One of these:
Been here before John?
https://www.diynot.com/diy/threads/extractor-fan-with-fused-isolator.523357/Sponsored Links
One might suspect the MIs - which way well have 'required' both a 3-pole isolator and a 3A fuse!
Kind Regards, John
Hi all. Thanks for your feedback. Yes, we have been here before. Donrkebab posted exactly the same issue, back in 2019 but we didn't seem to get to the answer of how to wire it up, just lots of more questions about specifics and regulations. The timed extractor fan will be set on and off by means of a pull chord, integrated into the lighting circuit. The fan manufacturer, specified this type of switch. The switch is a 13amp switch, with the feed being 10 amp, plus a separate 3amp fuse. Whats baffling me is what is the point of having two separate fuses, when the main power feed will be going through the L1, L2 and N connections, then wire up the L-in and L-out. Doesn't make any sense but regulations specify this type of switch so what would be the best way to wire this up?
Have a look at @bernardgreen s diagrams in the linked thread.
Whether this is achievable for you depends on the layout of your wiring.
That's the cause of much of the discussion here; regulations do not specify this type of switch (isolator), or fuse!
HI RandomGrinch. Thanks for your feedback to this never ending conundrum of a wiring diagram for just the isolator switch. If it helps in getting any closer to the answer, my wiring for the bathroom lighting circuit, with a pull switch and extractor fan is on this link,
I gotta say, the cowboy job that was originally installed, has now been ripped out and set to the wiring diagram I used yesterday, from the link above, and so far, all is well, except the connection up, of the isolator switch and fans. I'm thinking the best thing is to maybe contact the manufacturer of the switch for their guidance on this. After all, their the ones that designed this monstrosity that is baffling everyone.
I gotta say, the cowboy job that was originally installed, has now been ripped out and set to the wiring diagram I used yesterday, from the link above, and so far, all is well, except the connection up, of the isolator switch and fans. I'm thinking the best thing is to maybe contact the manufacturer of the switch for their guidance on this. After all, their the ones that designed this monstrosity that is baffling everyone.
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.
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.
Interestingly (and this is a side point), I'm not sure when 3pole fan isolators became a standard accessory (early 90s? @securespark will probably remember?) but it wasn't unknown for a switch fused spur to be used, with the switched live jointed through in a connector block in the back of the box, so that it had the effect of stopping the fan but leaving it live (and the neutral floating upto live potential as well). I'm still finding them in 2022 and I am sure I still will for quite a few years yet.
So, at the fan isolator switch, can we assume your wiring is as in your web link?:
In which case, as in Bernards and Plugwashs diagrams (exactly the same) - for the 'optimum' solution, your wiring will need to be modified.
However, if modifying the wiring would cause too much hassle, fusing only the permanent live to the fan would be a compromise.
The way fans are designed to monitor the switched live, means there is very little risk of causing, or being damaged by overcurrent.
The only risk being, if the fuse blows, the fan may be assumed to be dead and isolated, when there is still a live feed.
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Amen brother plugwash!!! What you have said, makes sense. The manufacturer of the fan, haven't stipulated your suggestion. I think I'll try wiring the 3 core with earth, into the L1, L2 and N terminals and the feed out, respectively. Then chuck the power back on and wait for the bang, lol. It shold be ok to wire this way as the L1, L2 and N terminals are protected by a 10a fuse, built in. Right, let the fire works begin.
RandomGrinch, this is what I was thinking should happen, how to incorporate the 3a fuse terminals that are in the back of the isolator switch, that would then monitor only the fans. It's almost like the Live feed, needs to be connected to the Lin and Lout terminals to complete the circuit. So if the fans do throw a wobbler, the 3a fuse would blow, taking the fans operation out, but as you said, would still keep a current live. In any instance though, common sense prevails and isolate the power at the CU before attempting the repair, if needed.
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?
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