Bathroom extractor on with dimmable lights?

[D00DY_T00DY]

Now recently we've been working at a job and the customer requested dimmable spots throughout the house including the bathroom with an extractor switched on with the lights. it hasnt been second fixed yet but im curious about how it will work so my best guesses are

The fan works normally with the lights

The fan works with the lights but slows down when the lights are dimmed but full speed when lights are switched off and it's on its timer

The fan doesn't turn on until a certain threshold(half way etc) then the fan works as normal.

I'm more inclined towards the third option. Thought it'd be fun for people to guess and I'll let them know once we second fix.

 

[gazdkw82]

Is there such a thing as a 2 gang switch with only 1 dimmable?

 

[D00DY_T00DY]

Is there such a thing as a 2 gang switch with only 1 dimmable?

It's wired so the switch wire from the one gang switch for the spots in the bathroom turns on the fan above with a permanent live to keep it running for 5/10/15minutes with a fan isolator switch above

 

[telectrix]

Is there such a thing as a 2 gang switch with only 1 dimmable?

easy with click mode modular switches, but you'd need to fit outside the bathroom.

 

[happysteve]

You don't want to be running the fan through the dimmer.

2G grid switch, populated with switch (1-way will do, or DP if you want to switch the neutral too) and dimmer knob. Permanent live to switch. Switched live (and permanent live) go to fan isolator, along with N. Switched live also goes to dimmer input. Dimmer output goes to lights.

Client uses switch to turn lights and fan on, and lights off (with fan running on to timer). Dimmer knob sets the brightness of the lights.

If in doubt, draw it out!

 

[D00DY_T00DY]

You don't want to be running the fan through the dimmer.

2G grid switch, populated with switch (1-way will do, or DP if you want to switch the neutral too) and dimmer knob. Permanent live to switch. Switched live (and permanent live) go to fan isolator, along with N. Switched live also goes to dimmer input. Dimmer output goes to lights.

Client uses switch to turn lights and fan on, and lights off (with fan running on to timer). Dimmer knob sets the brightness of the lights.

If in doubt, draw it out!

What would happen running a fan through a dimmer though?
And a very good solution however can't quite get my head around how to do it

So permanent live to the fan isolator then to the switch so then the switched live from the one way switch one to the isolator and the other to the dimmers common? then the switched live from the dimmer to the spots? have I got that right?

 

[happysteve]

Nearly. You run the permanent live to the common in the 1-way switch in the 2G grid. The other terminal of the 1-way switch is your switched live.

You take a feed from the permanent live (switch common) AND from the switched live up to the fan isolator. As you correctly say, you also take the switched live (from the 1-way switch) on a very short bit of cable to the dimmers common, then as you say the switched live from the dimmer to the spots.

I suppose if your permanent live is up at the isolator, then you would feed the 2G grid switch from there (but before the isolator, obviously, so turning off the isolator doesn't turn off the lights).

Sorry, probably a hundred times easier to explain by drawing it out, but I don't have the energy right now to draw it out!

I think you've basically got it

Running a fan through a dimmer can lead to unpredictable behaviour. I don't know for sure; but I know that speed control of fans requires special controls, not dimmers.

 

[davesparks]

Connecting the s/l to the fan from the output of the dimmer does work, I've seen it done in a couple of bodged installs. I wouldn't my advocate doing it, nor would I install it this way myself.

There used to be a dimmer available which had both a dimmed output and a switched output from the single knob which I have used to achieve the desired result here.

 

[D00DY_T00DY]

Nearly. You run the permanent live to the common in the 1-way switch in the 2G grid. The other terminal of the 1-way switch is your switched live.

You take a feed from the permanent live (switch common) AND from the switched live up to the fan isolator. As you correctly say, you also take the switched live (from the 1-way switch) on a very short bit of cable to the dimmers common, then as you say the switched live from the dimmer to the spots.

I suppose if your permanent live is up at the isolator, then you would feed the 2G grid switch from there (but before the isolator, obviously, so turning off the isolator doesn't turn off the lights).

Sorry, probably a hundred times easier to explain by drawing it out, but I don't have the energy right now to draw it out!

I think you've basically got it

Running a fan through a dimmer can lead to unpredictable behaviour. I don't know for sure; but I know that speed control of fans requires special controls, not dimmers.

Right think I've got it just thought it'd be interesting to find out how the fan reacted. never know until someone tries it haha probably resulting in a broken fan but fun nevertheless

 

[D00DY_T00DY]

Connecting the s/l to the fan from the output of the dimmer does work, I've seen it done in a couple of bodged installs. I wouldn't my advocate doing it, nor would I install it this way myself.

There used to be a dimmer available which had both a dimmed output and a switched output from the single knob which I have used to achieve the desired result here.

We thought nothing of it until it came around to getting temporary lights on for the joiner until we're back again so I'm putting the board on and my boss the switches so for the time being it's just a one gang white plastic switch but he brought up the question of "is that gonna work?"

 

[gazdkw82]

Connecting the s/l to the fan from the output of the dimmer does work, I've seen it done in a couple of bodged installs. I wouldn't my advocate doing it, nor would I install it this way myself.

There used to be a dimmer available which had both a dimmed output and a switched output from the single knob which I have used to achieve the desired result here.

This was what I was referring too