Discuss Bathroom extractor fan without fuse in the UK Electrical Forum area at ElectriciansForums.net
Totally agree.I think that the makers put an FCU (with a 3amp fuse) in their diagrams to cater for where the fan is powered from a ring final and the fan and the connecting wiring need to be protected from a fault current limited only by a 32amp MCB.
IMO there is no need to 'fuse down' a fan supplied from a 6amp lighting circuit. There are squillions of them installed like that, everywhere, many of them by me.
This is true but what are the chances.Some non timed fans ask for 1A fuse, manufacturers requirement takes president so if you installed incorrectly, customer could insist you carry out a costly upgrade to comply at your cost. If you don't tell client you are leaving yourself legally exposed. Is it worth risking your business for a fan?
The point of the fuse is to provide overcurrent protection not fault protection.If it's keeping you awake I'd pop an inline fuseholder inside the fan itself, can't say I'd ever bother myself as like said it's debatable a 3A 1361 fuse would beat a B6 MCB anyway.
Or you could do like barratt homes and stick a sw/f/sp marked "fan" that in fact controls the whole bathroom lights & all and completely miss the whole point of having a fan isolator and causes the likes of me to spend an hour trying to trace a break in a circuit before realising what amateur fwits I'm following around.
Which pole of the TP isolator does the fuse protect, switch live or permanent live.If he uses a fused TP&N isolator, he's just has to put in a suitably sized fuse
Sounds a right performance.you can wire it in a way that the fuse is in line with the perm and switched live of the fan by using a double pole light switch. Excel 3 Pole Fused Fan Isolator Switch - White | QVS Electrical Wholesalers - http://www.qvsdirect.com/excel-3-pole-fused-fan-isolator-switch-white
no probs mateAha, I was just looking for that after trawling through fan specs, most helpful, thanks very much.
no not really if your chucking the cables in on a 1st fix.Sounds a right performance.
Hi H, you are not alone. Lee's 3 pole fused isolator is one of the many neat things I have learnt here. CheersIve been out the loop for10ish years and slowly getting back into it all again because it gives me something to focus on; the non fused fan isolators were familiar, never seen these fused ones until now;
With Tin Hat On, I'm hoping I've got it : the unit has a separate fuse to the 3 pole switch so we can fuse the incoming L and then split it into L for the fan (via 3pole) and send L off to the other half of the new DP light sw, when it comes back it goes into as SL (via the 3pole). Clear as mud ?I don't get these fused triple-pole switches, they only fuse one of the poles so what is the point. May as well use a standard triple-pole switch with a two gang grid with two fuses fitted. Am I misreading this.
could do but will look rubbish.I don't get these fused triple-pole switches, they only fuse one of the poles so what is the point. May as well use a standard triple-pole switch with a two gang grid with two fuses fitted. Am I misreading this.
Spot onWith Tin Hat On, I'm hoping I've got it : the unit has a separate fuse to the 3 pole switch so we can fuse the incoming L and then split it into L for the fan (via 3pole) and send L off to the other half of the new DP light sw, when it comes back it goes into as SL (via the 3pole). Clear as mud ?
Both L and SL for fan can be fused, but it needs another pole on the light sw and cabling.All cartridge fuse only one pole for overload, just like an inline fuse ?!
edit missed the last posts, but still I would guess it only fused the one pole for overload
Does the switch come with instructions for this because it would be easy to get it wrong.Both L and SL for fan can be fused, but it needs another pole on the light sw and cabling.
No because there is a few ways to achieve the same outcome.Does the switch come with instructions for this because it would be easy to get it wrong.
Must admit I have never seen these switches. They seem to be a solution for a problem which isn't really there and only solves the so called problem by 50% leaving the installer to put in place the rest of the solution. This really should be made clear by the manufacturer.No because there is a few ways to achieve the same outcome.
Must admit I have never seen these switches. They seem to be a solution for a problem which isn't really there and only solves the so called problem by 50% leaving the installer to put in place the rest of the solution. This really should be made clear by the manufacturer.
I agree but do the manufacturer make that clear. Be interesting to undertake a study, take 10 sparks, give them the necessary parts and cable and see how many come up with the correct circuit.Why do they only solve half the problem? Generally I use the circuit shown by Richard Burns (above), so the line supply to the bathroom lighting and fan goes via a 3A fuse before any switches. Whether you use a single plate solution or two separate accessories makes no difference.
The fuse is not required to protect the switched line from overload, however if the fuse blows and the fan stops and then someone is working on the fan they will be expecting that the fuse has removed power from the fan however the switched line would still be live and subject someone to the risk of shock.Correct me if I'm wrong the 3A fuse is as posted for overload protection the 3 pole switch for isolation. I think the fan is powered via live/line and neutral therefore fuse in perm.live the switch wire just triggers the timer and not powering the fan motor.
Its your choiceWhich pole of the TP isolator does the fuse protect, switch live or permanent live.
I think you are thinking this too muchThe fuse is not required to protect the switched line from overload, however if the fuse blows and the fan stops and then someone is working on the fan they will be expecting that the fuse has removed power from the fan however the switched line would still be live and subject someone to the risk of shock.
Whilst you might say anyone with any sense will switch off the isolator, since these are domestic fans non professional persons are likely to be investigating and therefore may be subject to a shock risk.
Looks like it is wired back to front.Presumably the option is there to wire it as you require however I would expect that most people might wire it like this:
View attachment 34115
As this covers the most obvious arrangement that is identified on most fan installation instructions (assuming the TP isolator has a 3mm contact gap)
That is really rather the whole point, to ensure the whole of the fan is fused down, not just one half of the supply.Looks like it is wired back to front.
Feed to the light switch should be taken from the unfused side of the fuse.
Like I said before the switch is a half baked idea to solve a problem which isn't a problem in the first place.Looks like it is wired back to front.
Feed to the light switch should be taken from the unfused side of the fuse.
Agreed but it has been manufactured to fuse only one pole leaving the installer to figure out the rest. I guarantee these isolators have been fitted the conventional way leaving only one pole fused there is absolutely no doubt about it.
There would be an argument the switched live will still be live if the fuse blows, not from me but I must agree with the 3A fuse being used to prevent fire, would it really blow if the fan locked before the windings heated the enclosure enough to catch fire. I thought these fans incorporated thermal fuses anyway.My understanding is the 3a fuse is (laughably) intended to prevent the fan catching fire in the event of the motor seizing. As a timed fan will not operate without the permanent live it would seem to me that only fusing this pole and not the switched live would still achieve that (comical) aim.
Maybe the next amendment will require all fans to be constructed of non combustible material....ie sheet steel. Or the installer must construct a non combustible enclosure around the entire bathroom.
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