What can I use to replace 20A DP switch outside bathroom

[robine]

Hey there,

I've got a 20A DP switch outside the bathroom that is used to switch the bathroom lights on and a fan. I think a DP is overkill and if possible, I'd like to replace this switch with a single touch switch. If a single touch switch isn't possible, perhaps a 2 gang switch like this would work:

https://www.amazon.co.uk/Wallpad-Capacitive-Sensor-1-200w-Switch/dp/B01G29S7UM

The photo of the wiring of the bathroom switch is shown here: https://i.ibb.co/6b9WgCv/20190831-151759.jpg

If touch isn't an option, could I just replace this DP with a 2 gang 2 way switch like this: https://www.screwfix.com/p/lap-2-gang-2-way-10ax-light-switch-white/45240

Many thanks in advance,

Robin

 

[Rob.]

Well looking at the existing wiring you've 2 circuits there. 

Does it switch anything else on aside from the lamps at the same time? Extractor fan, de mist on mirror etc...

 

[Evans Electric]

As Rob said ,  looking like two items being switched ....which seems slightly strange ...I assume theres a reason for the Sparky to do it that way .   

I wouldn't buy any touch switches until you know what is being switched there .       ( I wouldn't be buying any touch switches anyway but thats your choice)  

Can you disconnect  say  L1  in that switch & see what doesn't work ....then  reconnect & remove N1   , see what doesn't work . 

If you're a DIYer    make sure the circuit is DEAD  before messing . 

 

[kerching]

Unless it's a DP switch because the fan is common to two rooms and is switched by individual room lights. The DP switch would stop a back feed from the switch in room one putting on the fan and thus putting on light in room 2

fairly common around here but usually achieved with old style 15A DP pull,switches

just saying

 

[Andy™]

Unless it's a DP switch because the fan is common to two rooms and is switched by individual room lights. The DP switch would stop a back feed from the switch in room one putting on the fan and thus putting on light in room 2

fairly common around here but usually achieved with old style 15A DP pull,switches

just saying

and always fun once someone replaces the switch with a normal switch

 

[kerching]

and always fun once someone replaces the switch with a normal switch

Which I did when I was an apprentice 

did job

left

back to shop

phone call

"light is on in my other bathroom and won't go off"

whoops

 

[robine]

Well looking at the existing wiring you've 2 circuits there. 

Does it switch anything else on aside from the lamps at the same time? Extractor fan, de mist on mirror etc...

Yes, there's a fan in the bathroom as well which this switch also turns on. Thanks.

As Rob said ,  looking like two items being switched ....which seems slightly strange ...I assume theres a reason for the Sparky to do it that way .   

I wouldn't buy any touch switches until you know what is being switched there .       ( I wouldn't be buying any touch switches anyway but thats your choice)  

Can you disconnect  say  L1  in that switch & see what doesn't work ....then  reconnect & remove N1   , see what doesn't work . 

If you're a DIYer    make sure the circuit is DEAD  before messing . 

Thanks, I'll do that; disconnect L1 and see what works, then put it back and remove N1.

 

[robine]

Unless it's a DP switch because the fan is common to two rooms and is switched by individual room lights. The DP switch would stop a back feed from the switch in room one putting on the fan and thus putting on light in room 2

fairly common around here but usually achieved with old style 15A DP pull,switches

just saying

There are 2 bathrooms, each with a fan and lights, but the fans and lights are not common to either bathroom. There is a DP switch outside each bathroom and that switch only controls that bathroom's fan and lights. This is a fairly new build property, maybe 2014.....

 

[Evans Electric]

If theres not one fan which is common to both bathrooms , speaking for myself I'm not sure why  there are two DP switches  TBH .  

(  Touch switches  are solid state switching  , I don't see how they can have the 3mm  switch gap TBH .  )     

Your house doesn't have one of those "whole house "  ventilation systems then ?    Theres a separate fan in each room ? 

 

[robine]

If theres not one fan which is common to both bathrooms , speaking for myself I'm not sure why  there are two DP switches  TBH .  

(  Touch switches  are solid state switching  , I don't see how they can have the 3mm  switch gap TBH .  )     

Your house doesn't have one of those "whole house "  ventilation systems then ?    Theres a separate fan in each room ? 

I'm not actually sure what type of ventilation system the flat has..... each bathroom has a fan/extractor and lights, and outside each bathroom is a single DP switch.

 

[Evans Electric]

Is it an actual fan  or  just a grill on a common system  I wonder ?      Theres usually a vent unit mounted in the loft with a load of ducting  spidering off   & it does the heat recovery thing  at the same time . 

Someone will know why theres two DP switches,  give it time . 

 

[Andy™]

maybe there is a fused spur that does just the fan, since some manufacturers state there must be a 3a fuse

 

[Rob.]

(  Touch switches  are solid state switching  , I don't see how they can have the 3mm  switch gap TBH .  )     

You only need the 3mm gap for isolation, not for functional switching. 

 

[robine]

Is it an actual fan  or  just a grill on a common system  I wonder ?      Theres usually a vent unit mounted in the loft with a load of ducting  spidering off   & it does the heat recovery thing  at the same time . 

Someone will know why theres two DP switches,  give it time . 

Yesterday evening, in both bathrooms with the light switch to each bathroom turned off, I realised that the bathroom fans are actually extractors and work without the light switch being turned on. Just using a piece of toilet paper, the extractors in each bathroom are able to "suck" the toilet paper up and it sticks to the fan. This is with the switch off. I'm wondering now if the lights in each bathroom are on 2 separate circuits. One circuit is for the normal non-IP44/IP56 lights and one separate circuit for a IP44/56 light that is above the shower cubicle.... is that likely? Thanks.

 

[Evans Electric]

You only need the 3mm gap for isolation, not for functional switching. 

Ah   OK  thanks , I'd not thought of that .  

 

[Evans Electric]

esterday evening, in both bathrooms with the light switch to each bathroom turned off, I realised that the bathroom fans are actually extractors and work without the light switch being turned on. Just using a piece of toilet paper, the extractors in each bathroom are able to "suck" the toilet paper up and it sticks to the fan. This is with the switch off. I'm wondering now if the lights in each bathroom are on 2 separate circuits. One circuit is for the normal non-IP44/IP56 lights and one separate circuit for a IP44/56 light that is above the shower cubicle.... is that likely? Thanks.

No it doesn't make sense  to be honest ,  I could imagine the shower light on it's own switch possibly . 

But now you've looked at the "extractors" it sounds more like you have an all house vent / heat recovery  system   , noting you said house built in 2014  ,  all the energy saving stuff had kicked in by then . 

I'm taking a guess now ....the vents are on trickle extract  but switching the light on may start a boost .   You could try that by standing on a chair , on one leg , with your ear to the vent ,  switch light on with other foot and listen for a boost in airflow . 

I'm definitely thinking forget the touch switch at this point . 

 

[ProDave]

My guess is you have a multi (two) speed extractor fan, and the speed selection is not a simple switching on or off of a 240V supply, but rather is closing and opening a pair of "control" contacts from the fan, which may or may not be 240V.  So not much you can do to alter the arrangement you have.

If it was a full mvhr system you would have an air duct on every ceiling in every room, some supplying fresh air in and others extracting stale air.

 

[Andy™]

i think you need to get someone in to have a look... too much guessing going on to get a proper answer

 

[robine]

No it doesn't make sense  to be honest ,  I could imagine the shower light on it's own switch possibly . 

But now you've looked at the "extractors" it sounds more like you have an all house vent / heat recovery  system   , noting you said house built in 2014  ,  all the energy saving stuff had kicked in by then . 

I'm taking a guess now ....the vents are on trickle extract  but switching the light on may start a boost .   You could try that by standing on a chair , on one leg , with your ear to the vent ,  switch light on with other foot and listen for a boost in airflow . 

I'm definitely thinking forget the touch switch at this point . 

I did the sound test you suggested, listening to the sound of the extractor fan with the switch on and off and there was no difference at all.

I'll be disconnecting L1 and seeing what works and then reconnect that and then disconnect N1 and see what works with that.

Thanks all for the advice and help here  

 

[Doc Hudson]

In all of this assuming and guess work has anyone actually tested the wires to verify if they are supplied off the same circuit?

Doc H.