Extractor fan with fused isolator

[mjas]

Just to comment on the comments. This is the existing installation that I have inherited from the previous house owners so (for me) it's always been wired this way but I don't know when it was first installed. It is difficult to see from the picture but the connections are as suggested by JohnW2 (i.e. correct). I recognise that some sleeving may be missing on the earths and the switched live isn't correctly coloured to meet with current guidelines/legislation. These are all issues I intend to resolve.

 

[mjas]

For anyone still interested, and anyone else who is wondering about taking on a similar task, I've now completed the installation of the new fan. Taking into account the feedback from the fan suppliers (they confirmed that a fused spur was required) and all of the other sound advice, I've included both a 3A fused spur and a separate isolation switch. Possibly overkill but for an extra £5 or so I couldn't see a reason not to do it. There are now no sections of cable without outer insulation sticking out of the junction boxes and the boxes are screwed down with the cables clipped. Just for convenience of the cabling runs I haven't used the fuse in the isolation switch to manage the fused spur.
And it works!
Kind regards to all who have commented.

 

[EFLImpudence]

Taking into account the feedback from the fan suppliers (they confirmed that a fused spur was required)

That is not true. It is not 'required' - by the regulations.

I've included both a 3A fused spur and a separate isolation switch. Possibly overkill but for an extra £5 or so I couldn't see a reason not to do it.

Neither is 'required'.

Just for convenience of the cabling runs I haven't used the fuse in the isolation switch to manage the fused spur.

What does that mean?

 

[AndyPRK]

what a lovely set of fuses

watch from 9 mins or 11 mins for fuses

 

[JohnW2]

.... Taking into account the feedback from the fan suppliers (they confirmed that a fused spur was required) and all of the other sound advice, I've included both a 3A fused spur and a separate isolation switch. Possibly overkill but for an extra £5 or so I couldn't see a reason not to do it.

Thanks for the update.

As for "reasons not to do it", in practical terms they are probably too weak for most people to worry about, but doing anything to an electrical installation which results, 'unnecessarily', in an increased number of screwed connections theoretically increases the number of points of potential failure (e.g. connections/joints becoming loose) and, for the really risk-averse people, in the very (but extremely rare) worst-case scenario, such loosened connections could theoretically start a fire.

Kind Regards, John

 

[mjas]

Suggestions around comment 20 in the thread about using the fuse in my isolator switch shown in the first photo in my original post.

 

[mjas]

…..

What does that mean?

I was replying to suggestions around comment 20 in the thread about using the fuse in my isolator switch shown in the first photo in my original post, rather than use a separate fuse.

That is not true. It is not 'required' - by the regulations.

Neither is 'required'.

Regarding the query on the fused spur, the manufacturer stated "The wiring diagram does comply and as a manufacturers recommendation, this is the way to install the units". If I hadn't complied with that and there was an issue I assume I'd have no comeback.

Overall, I do now have more screwed connections with the associated risk John has identified, but apart from that is there really any other downside?

 

[EFLImpudence]

I was replying to suggestions around comment 20 in the thread about using the fuse in my isolator switch shown in the first photo in my original post, rather than use a separate fuse.

Never mind.

Regarding the query on the fused spur, the manufacturer stated "The wiring diagram does comply and as a manufacturers recommendation, this is the way to install the units". If I hadn't complied with that and there was an issue I assume I'd have no comeback.

Note they say "recommendation".

It makes absolutely no difference to the fan whether you have a switch or not, and
fuses are to protect the cables, not appliances. As such one is not needed.

 

[ban-all-sheds]

I don't know what your numbers mean

Why not?

 

[ban-all-sheds]

What do you mean by "both feeds" and "the second supply"?

If you are perhaps talking about separately fusing the L and S/L feed to the fan then, as EFLI pointed out, that introduces a theoretical hazard - if the fan stopped working because a fuse in the permanent L feed blew, if one then opened up the fan to investigate (forgetting to operate the isolator, since the fan was not running), one could be 'surprised' (or worse) by a live S/L if the light was on.

Kind Regards, John

There's always Plan B - replace the light switch with a DP one.

The switched FCU ticks all the boxes, if people want, for 3A fusing (both L & SL), and local all-pole isolation, and has only one fuse, so no concern such as yours.

 

[JohnW2]

There's always Plan B - replace the light switch with a DP one.

True, but that would probably entail appreciably more new wiring.

 

[BoutTime]

I know it's a little old but a very interesting thread this. A lot of common sense and reasoning. Our downstairs WC timer fan has packed up (gets hot and smells too) and it has no isolator fitted. So until I replace it we have no light we can use as the switch activates the fan. The house is almost 20 years old. The fans in the bathroom and ensuite have isolators. The fan in the utility doesn't work but appears to be controlled via a separate conventional light switch.
So they are all different. To me it would appear the only reason for installing the isolators is to prevent the fans running at night when using the toilet and waking people up.
That said I may well just fit a pull cord isolator adjacent to the replacement fan as I can certainly see the convenience of being able to isolate it in case of failure. I won't bother with a fuse. I'll be fitting an Xpelair DX100PIR so only 2 pole L and N connections required.

 

[EFLImpudence]

You still seem to be confused between isolators and switches.

 

[JohnD]

...to prevent the fans running at night when using the toilet and waking people up....

An even better solution is to use a modern fan with a ball-bearing motor that is practically silent.

 

[JohnD]

..until I replace it we have no light we can use as the switch activates the fan.

If you own a screwdriver you can disconnect at the terminal block inside.