Bathroom extractor fan without fuse

[Midwest]

Which pole of the TP isolator does the fuse protect, switch live or permanent live.

Its your choice

 

[Midwest]

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.
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.

I think you are thinking this too much

 

[Deleted member 26818]

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)

Looks like it is wired back to front.
Feed to the light switch should be taken from the unfused side of the fuse.

 

[Richard Burns]

Looks like it is wired back to front.
Feed to the light switch should be taken from the unfused side of the fuse.

That is really rather the whole point, to ensure the whole of the fan is fused down, not just one half of the supply.

 

[Deleted member 26818]

Yes, just don't like the light being fused with the fan.

 

[westward10]

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.

 

[Midwest]

The same could said of the hallway & landing light switch. Should we not be wiring the ground floor & first floor lighting from the same mcb. If we use a non fused TP&N isolator, if a fan malfunctions, the same non professional person, could put his pinkies in there and get a shock. There's just no helping some people.

The use of a fused TP&N switch, in it's simplest form, allows the installer to 'take account of the manufactures instructions', by fusing the live supply to a fan. If that's what you want to do.

 

[westward10]

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.

 

[Deleted member 9648]

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.

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.

 

[westward10]

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.

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.