Extractor fan with fused isolator

[JohnW2]

It’s very siqmilar to any electrical equipment isn’t it. Make sure it is fully isolated first

Indeed it is. However, that does not mean that it is wise or sensible (or even 'responsible') to unnecessarily increase the risk which will be faced by someone who does not "make sure that it is fully isolated first".

Having fuses in both the permanent and switched live feed to a timer fan (or, indeed, just one fuse only in the perm L) introduces essentially the same risk as does having a fuse in the neutral. In any of those cases, the blowing of one fuse can result in the equipment appearing dead whilst there are still live parts within it.

In the case of neutral fusing, you appeared to be agreeing that it was an undesirable thing, because of issues of 'personal safety'. If so, I would expect you to feel the same about the fan fuse issues. If you don't, why the difference?

Kind Regards, John

 

[mjas]

Just thought I'd share my junction box to complete a couple of comments made earlier in the thread. I've excluded the earth connections from the diagram (the cable that has yellow tape on it and is a neutral). The lights are controlled from either of 2 switches (2 way?) and connect on to a transformer and 6 low voltage spots. The transformer includes a 2A fuse in it. The original timer connection to the fan was connected into this switched live (but at the transformer end). The original permanent live and neutral were from elsewhere in the lighting circuit (6 feet away). If I do go down the fused spur route (and I appreciate that feedback has been divided) I will start at this junction box. Thank you for all your comments and the time and effort to send them, I wasn't expecting any response so for it to have generated so much feedback has been very helpful, although it's moved on somewhat from my original question of where to position the fuse!
Kind regards
Mike

 

[EFLImpudence]

Edit - My error

 

[AndyPRK]

I don't know John.

I guess someone could remove a fuse, thinking they were isolating it, and they weren't. So on balance, maybe better without a fuse (providing its connected to a 6A mcb)

 

[JohnW2]

I don't know John. I guess someone could remove a fuse, thinking they were isolating it, and they weren't. So on balance, maybe better without a fuse (providing its connected to a 6A mcb)

'A fuse' is no problem if it protects both the L and S/L (and hence also the light), as per some of the arrangements suggested in this discussion - since removal of that fuse then would isolate everything in the fan.

However, as you say, using a 3A fuse on a 6A circuit is pretty daft in the first place, since it's unlikely to achieve much, if anything (the 6A MCB could well operate before a 3A BS1362 fuse).

Kind Regards, John

 

[333rocky333]

whats with the reds joined to earth. all a bit rough sorry

 

[AndyPRK]

Don’t think they are.
Just unsleaved cpc’s under reds ?

 

[scousespark]

I agree with Rocky. It certainly appears that the top cable has the red conductor in a terminal which also has a cpc connecting to the bottom left terminal.

 

[AndyPRK]

Op said yellow sleeve over black signifies switched live

Bottom right terminal cpc

 

[scousespark]

The original permanent live and neutral were from elsewhere in the lighting circuit (6 feet away).

Have you wired up this JB, or has it always been wired that way?

 

[JohnW2]

I agree with Rocky. It certainly appears that the top cable has the red conductor in a terminal which also has a cpc connecting to the bottom left terminal.

That's not how it looks to me.

I presume that the conductor leaving the bottom of the LH terminal is the yellow-sleeved one which the OP said is a 'neutral' (but which, as Andy has said, is more likely to be a switched live). However, since it disappears behind cables, we can't see where that yellow-sleeved conductor actually goes. Per the below, it doesn't look as if it goes to the bottom ('earth') terminal, so I would think that the most likely answer is that it comes from ('out of the side of') the cable which is the 'second from left' of those at the bottom.

However, if that's correct, it presumably would mean that the bare CPC of that cable is being used as a live conductor (probably a switched live, rather than the 'neutral' suggested by OP), since both the red and black conductors from that cable can be seen - which, if true, is clearly unacceptable! However, maybe that's not the case - only the OP can clarify exactly what is going on.

Kind Regards, John

 

[AndyPRK]

I can clearly see black insulation under the yellow sleeve.

I think the reds goto the 4th terminal. But that is difficult to see for sure!

 

[JohnW2]

I can clearly see black insulation under the yellow sleeve.

Yes, I thought that - but at the time, I thought I had otherwise accounted for the blacks from all five cables.

However, I think I was wrong .... on reflection, I think what ends up as that yellow-sleeved conductor is actually the black from one (it's hard to tell which) of the right-hand two cables at the bottom - i.e. (my blue squiggle) ...

I think the reds goto the 4th terminal. But that is difficult to see for sure!

Indeed - but I thing the arrangement is pretty clear - going clockwise from the top one, the terminals appear to be neutral, perm L, earth and S/L.

In other words, in terms of 'what is connected to what', there could well be nothing wrong with that JB.

Kind Regards, John

 

[flameport]

Plenty wrong with that - at the very least:
- conductors not correctly identified
- box not secured to anything (unless there is a hidden screw under the tangle of wires bottom right)
- cables not secured
- single insulated conductors outside of the box

 

[JohnW2]

Plenty wrong with that - at the very least:....

Indeed so. That's why I said that there might be nothing wrong with it "in terms of 'what is connected to what' " (given that some people had been implying the converse)

Kind Regards, John