Confusing bathroom lights and fan wiring

[stringsonfire]

Hi

I'd like to separate my bathroom lights from the fan at the switch, but it's a mess. Can you tell from the photo what's actually been done here, and how can I safely figure out what all of these wires are for?

For full context:

• I've had IP65 downlights fitted in my bathroom, using Hue Smart Bulbs, which should be left on at the switch, but I can't do this because that would also leave the fan on
• I live in a flat with a single extraction duct for the bathroom and kitchen with an inline fan
• There is a fan isolator high in the airing cupboard (fan is located above, but access is very difficult)
• The fan can be turned on/off instantly using a fan switch in the kitchen or the light switch for the bathroom

Thanks!

 

[Pete999]

Some professional help will not go amiss, Mate

 

[SparkyChick]

Given the setup, I have to agree with @Pete999 .

The best advice is consult a local electrician.

 

[westward10]

Someone has done some rather non conventional wiring there through a double-pole switch and it is highly unlikely we can give you advice from a distance. Yes it is possible and as suggested above seek professional help.

 

[littlespark]

You've got a little problem there, mate. That is a 20A double pole switch being used as a lightswitch. There is a live conductor being switched through terminals marked as neutral. Confusing.

As my esteemed colleagues have already suggested, an electrician will be able to make sense of it within a few minutes with the correct equipment

 

[stringsonfire]

The electrician who sorted the spotlights spent a while on it, couldn't figure it out and ran out of time. Guess I'll need to find another electrician...

 

[telectrix]

if you post your location 1 of us may be close to sort it for you.

 

[westward10]

As a matter of interest does the fan carry on for a while after the switch is turned off, the wiring from what I can make out suggests it does not.

 

[Octopus]

The electrician who sorted the spotlights spent a while on it, couldn't figure it out and ran out of time. Guess I'll need to find another electrician...

Find another one has to be a good idea

 

[mhar]

It isn't that unconventional! It is just a method of wiring using an sfcu to give isolation to all 3 live fan conductors whilst not isolating the bathroom light (so that you can see what you are doing!). Avoids having a triple pole isolator and is a neat way od doing things

 

[stringsonfire]

As a matter of interest does the fan carry on for a while after the switch is turned off, the wiring from what I can make out suggests it does not.

You're right, it doesn't stay on, turns off straight away.

if you post your location 1 of us may be close to sort it for you.

Welwyn Garden City, Hertfordshire

It isn't that unconventional! It is just a method of wiring using an sfcu to give isolation to all 3 live fan conductors whilst not isolating the bathroom light (so that you can see what you are doing!). Avoids having a triple pole isolator and is a neat way od doing things

Good to know it's possible. Any idea how?

 

[westward10]

Looks like double-pole switch to me using the neutral terminal for the lines and which does not isolate all poles if you include the neutral so yes I would say it is unconventional.

 

[westward10]

If it turns it straight off I would suggest it was or is now incorrectly connected assuming the three core cable runs to the fan and the fan has a run over function. From here we can only recommend getting an electrician involved I am afraid but it can be done.

 

[mhar]

You have a perm live to one supply pole of the dp light switch which is also taken to the in of the sfcu, the load pole is connected to the lamp. The fused out of the sfcu returns to the other supply side of the dp switch plus goes directly to the fan.The fused out of the dp switch goes to the fan as switched live. The supply n of the sfcu is also connected to the lamp, the out goes to the fan thus giving 3A fusing on both fan line conductors and all 3 fan live conductors can be isolated via the sfcu without affecting the operation of the light

 

[telectrix]

You have a perm live to one supply pole of the dp light switch which is also taken to the in of the sfcu, the load pole is connected to the lamp. The fused out of the sfcu returns to the other supply side of the dp switch plus goes directly to the fan.The fused out of the dp switch goes to the fan as switched live. The supply n of the sfcu is also connected to the lamp, the out goes to the fan thus giving 3A fusing on both fan line conductors and all 3 fan live conductors can be isolated via the sfcu without affecting the operation of the light

but when did OP mention a SFCU?

 

[westward10]

Is it just me but from that switch I cannot work out how the fan works. Due to the amount of neutrals that is not end of line and the neutral terminal with three browns, it looks like two but is three is the loop terminal so I suspect there is a shaver socket. The other brown on its own goes to the lights, the triple core conductors assuming that is the fan are isolated at the switch from the loop in lines?

 

[stringsonfire]

Is it just me but from that switch I cannot work out how the fan works. Due to the amount of neutrals that is not end of line and the neutral with three browns, it looks like two but is three is the loop terminal so I suspect there is a shaver socket. The other brown on its own goes to the lights, the triple core conductors assuming that is the fan are isolated at the switch from the loop in lines?

Just checked, the shaver socket power disappears when I turn off the light circuit breakers

 

[westward10]

Yeah I am singing out load here because the more I look at it the more it intrigues me. If those connections are original and your electrician hasn't changed them and this won't help you but may be of interest to another electrician you need to employ. Those two wires to the left which are part of the three core cable do nothing and the fan is connected direct from the lights or, there is a secondary live to the switch which does use those two wires to switch the fan. My conclusion is someone has incorrectly connected the fan.

 

[littlespark]

What have you got there? 4 twin&earths and a 3core and earth?
Instinct says the 3 core should got to the fan isolator, then onto the fan.... but where they are connected in the switch suggests otherwise.

There are too many cables there for anyone to give an educated guess without knowing what cables are at the kitchen switch or the isolator.

 

[westward10]

I believe you have live in, live out, output to the lights and a shaver socket output. The triple-core is totally confusing by the manner in which it is connected.

 

[Baddegg]

I think I would shed a real tear if I opened that up.......

 

[SparkyChick]

I think the key is the fact there (unless I've misinterpreted the OP) is one fan (ducted to process the kitchen and bathroom) and it's switched instantly from both locations.

But regardless, it looks like a right bodge.

 

[Toneyz]

This is what I think (and I apologise if it is repeating what Westward and SparkyChick have posted as I think they are thinking the same)
There is a lighting circuit feeding in and out of the switch.
One of the cables is for the shaver socket
The other twin&E to the bathroom lights this switches through N pole
FAN
There is an AHU, fan unit etc as described a 3 core and earth would of been taken to the bathroom and kitchen and is being used as a linked switch in both locations
A suggestion would be a 2g grid switch with one switch for the light and an engraved fan switch.
I don't think that the neutral should be in with the lighting neutrals.
If the OP does not want a switch for the bathroom it would be a case of the bathroom switch wire being put with the lighting circuit permanent live.
This is only a guess from posts and advise an electrician be sought to test and confirm.

 

[robd]

Just needs someone decent to look at it and suss it out doesn't look that drastic

 

[stringsonfire]

Thinking about it, the ideal way to have this would be a separate bathroom fan switch that works like a local isolator (be it in a separate box or grid switch) so that:

https://i.Upload the image directly to the thread.com/rBYIbaC.png

That way, I can use the Fan switch to turn the fan on and off, keeping my Hue lights always on, and when I eventually move out, the next people can leave the fan switch always on, and just control it with the light switch like they'd expect.

So anyone here in Hertfordshire?

 

[mhar]

but when did OP mention a SFCU?

Isn't that exactly the point of the question?
The op and his electrician have not recognised the wiring method, they have looked at a double pole switch and been baffled by it. This is a method that I first came across 10 years or so ago and was equally baffled but is a method I still occasionally use (admittedly usually with a dp mk logic ceiling pull switch). If I removed a switchplate and saw the wiring as per the photo my first thoughts wouldn't be wtf but I would be thinking the installer has cleverly seperated the fusing of both the fan's line conductors from the light switch and provided isolation of all live conductors to the fan (without affecting the bathroom light) for the cost of a couple of metres of 1mm t & e and a wago plus having avoided one of those beautiful fan isolator switches

 

[mhar]

 

[mhar]

The picture in the op is exactly the same as in my diagram above, hence my reply

 

[westward10]

The picture in the op is exactly the same as in my diagram above, hence my reply

I see what you are getting at now.

 

[SparkyChick]

Except that's not how it's wired.

From the OP, there are two switches that control the fan as the fan serves both the kitchen and the bathroom. The DP switch is there to separate the bathroom light switching from the fan switching so the bathroom light doesn't come on when the fan is turned on from the kitchen.

 

[Octopus]

I think the op needs some local competent assistance ....

 

[mhar]

Except that's not how it's wired.

From the OP, there are two switches that control the fan as the fan serves both the kitchen and the bathroom. The DP switch is there to separate the bathroom light switching from the fan switching so the bathroom light doesn't come on when the fan is turned on from the kitchen.

Ok, a variation on a theme. In my drawing (dare I call it an artistic masterpiece?)the bathroom light will not be on unless it is switched by the dp switch regardless of whether a switch in the kitchen is operating the fan as well. There is no back feed from the fan because of the use of the double pole switch

 

[Marcus Vaughan]

It isn't that unconventional! It is just a method of wiring using an sfcu to give isolation to all 3 live fan conductors whilst not isolating the bathroom light (so that you can see what you are doing!). Avoids having a triple pole isolator and is a neat way od doing things

But the neutral cannot be isolated?

 

[Toneyz]

But the neutral cannot be isolated?

Isolating what the fan?

 

[Marcus Vaughan]

Isolating what the fan?

Forget that, talking cross purposes, I posted the above by looking at the photo - not the drawing.

 

[Richard Burns]

I would think that if the electrician was having problems that the cables present at the fan may be the ones initially planned and the switching was then adapted to use the previously installed cables.
It sounds like a fairly logical original plan to use a double pole switch in the bathroom and kitchen to allow the fan to be switched on in either location without also operating the light that was not local to the switch.
However the actual wiring plan would need to be assessed with testing and inspection of all switches.
I can use the photographed cables to get a timed fan to work using twin and earth and 3 core but cannot work out how to avoid the timer function. Ah yes use a double pole switch for the fan and wago the permanent line and loop switched line/line in the fan.
A possible layout? obviously subject to verification.

 

[SparkyChick]

@Richard Burns - What software do you use to produce your diagrams? You always seem to be able to knock them up in double quick time and they are usually pretty darn good.

 

[Richard Burns]

@Richard Burns - What software do you use to produce your diagrams? You always seem to be able to knock them up in double quick time and they are usually pretty darn good.

Very kind of you, thank you. I do not usually do diagrams for work (because I am lazy) so I just use powerpoint for the forum diagrams.
I already have various accessories drawn out from previous diagrams and use connectors for the cables. Probably slower than a dedicated program but just one with which I am familiar .

 

[SparkyChick]

Very kind of you, thank you. I do not usually do diagrams for work (because I am lazy) so I just use powerpoint for the forum diagrams.
I already have various accessories drawn out from previous diagrams and use connectors for the cables. Probably slower than a dedicated program but just one with which I am familiar .

Sometimes the dedicated stuff does things that just get in the way and actually make it harder to draw a nice diagram. I used to use SmartDraw alot, then they added all sorts of features that 'made it easier'... yeah right... easier if you want a diagram laid out on this perfect grid.. anything else became a night mare.

I'm going to be cheeky and ask... any thoughts on possibly sharing say a PowerPoint with the common symbols in?

 

[Toneyz]

Richard has interpreted exactly on what I was saying in my post as said without on-site verification cannot be 100%.

 

[Toneyz]

As long as all are on the same circuit and you haven't got the neutrals interconnected between two lighting circuits.

 

[shaun1]

If you get somebody to just swap that double pole switch for a 2 gang switch, putting one pole on each switch, you should end up with a switch for the lights (which can be left on) and a switch for the fan. (This is assuming 1 pole is the lights and the other is the fan, but would be a good place to start)

 

[stringsonfire]

Some more information here.

• This wiring is original. The flat was built by Taylor Wimpy in 2013.
• The fan appears to be a CMEV.4E. Apparently, it's three speed, house-wide extractor designed to be always on, on a near silent low setting, with the medium and high speeds designed to be manually switched. Product information, including wiring diagrams, are here.
• I can't confirm if it is always on - either it's too quiet for me to tell, or it's not. As it only extracts from the bathroom and kitchen, I'm not sure it needs to be.

Kitchen Switch (there's a grey wire not connected to anything tucked in the box:
https://i.Upload the image directly to the thread.com/ay0nUhI.jpg

https://i.Upload the image directly to the thread.com/jw9EG0e.jpg

Isolator:

https://i.Upload the image directly to the thread.com/6W2HTOz.jpg

https://i.Upload the image directly to the thread.com/aiiG61C.jpg

https://i.Upload the image directly to the thread.com/2M1sM83.jpg


Wanted to add this to the first post to keep all the info in one place, but seems I can't edit the post, so sorry it's a bit everywhere now.

So this seems even more complicated than I thought. Am I not better off just removing live cables from the Bathroom Switch until the lights won't turn on, then putting them in a separate switch, and leaving the fan wiring as is?

 

[SparkyChick]

To answer your last question... no. Random removal of conductors is never a good plan.

Can you not isolate it fully, and work out the wiring by appropriate dead testing? Draw a diagram and then work out what needs to change at the bathroom end to achieve the desired result.

 

[Toneyz]

Nice hole at the back of the fast fix box.

 

[Toneyz]

The gray needs to be made safe at both ends as not needed.
Fan isolator needs to be changed to a switched fused spur fused to 3A.
Is the bathroom and kitchen lights on the same circuit as the fan?

 

[Pete999]

Nice hole at the back of the fast fix box.

Needs to be that big to get all the wires in

 

[Toneyz]

The gray needs to be made safe at both ends as not needed.
Fan isolator needs to be changed to a switched fused spur fused to 3A.
Is the bathroom and kitchen lights on the same circuit as the fan?

Needs to be that big to get all the wires in

The knock out at the top of Appleby fast fix boxes is big enough to get more cables than is there.

 

[Richard Burns]

So the supply is looped at the fan isolator and the bathroom switch, perhaps. Each switch that operates the fan is paralleled with three core cable (but the grey is used for neutral at the bathroom switch but only seems to go (possibly) to a connector block at the isolator).
I think the three core must have been the original plan but things changed (not for the better). I hope there is not a brown wire in the middle top terminal of the fan isolator. The fan isolator does not isolate the switched line but does isolate the permanent line and neutral, probably.
The fan is only switched from trickle to max boost.
9dB would be very hard to hear on trickle.
The fan switch could be separated out assuming my guesses are correct.
A somewhat confusing arrangement of wiring for a simple system, but perhaps logical when you are on site. Certainly not ideal; no need for a 3A fuse if fed from 6A lighting.
Bit of a guess at the wiring even though I cannot see all the connections in the TP isolator.

 

[stringsonfire]

I did this to the bathroom light switch:

https://i.Upload the image directly to the thread.com/raVHZik.jpg

This stopped the fan boost turning on with the bathroom light.

Is there any reason why I shouldn't simply separate the poles with a 2-gang light switch like this?