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Its your choiceWhich pole of the TP isolator does the fuse protect, switch live or permanent live.
Discuss Bathroom extractor fan without fuse in the UK Electrical Forum area at ElectriciansForums.net
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.
Correct a mundoCorrect 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 therfore fuse in perm.live the switch wire just triggers the timer and not powering the fan motor.
Yes, so I don't understand why the fans that require fusing don't come with one from the factory? Then it could be the right fuse, if BS1362 3A isn't ...Confirms one thing the fuse is not foolproof when it comes to preventing fire.
I'm off to de-fluff my fan
Reply to Bathroom extractor fan without fuse in the UK Electrical Forum area at ElectriciansForums.net
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