Motion sensor in bathroom

[CharlesBR]

Not sure how easy or difficult this would be but in order to get around the issue of the bathroom light not being switched off (using a pull cord) when someone finishes using the bathroom I am exploring the idea of fitting a motion sensor in place of the pull cord.
The bathroom has 3 LED downlights and an extractor fan (25w) fitted which goes off after 15 mins and is connected via an isolation switch.
Instead of the pull cord I want to fit a motion sensor so that if no movement detected after a few mins then circuit is switched off.
I have looked up in the loft and from a circular junction box goes a single two core plus earth 1.5mm2.
If possible what do I need to do?

 

[sparkwright]

You need to check if the new sensor requires a neutral or not.

The pull switch will have a permanent live, a switch live and hopefully an earth - but unlikely to have a neutral.

Personally I would find a motion sensor annoying - and a good old fashioned bolllocking on a semi-regular basis should put paid to any thoughts of anyone leaving the light on if done well.

 

[oldbutnotdead]

As above- get the lazy sods trained. One big problem with a motion sensor is when you slink into the loo at 3am after a night on the lash- you're blinded by the light and alert the household to your arrival. From a financial point of view payback will be a long way away with 15w of light in there.
The ideal fix (in a toilet only, not a bathroom) would be a motion detector set up as a 2 way switch with the pull switch as the other switch. Scenario- light switched on, motion detector waits until 3 minutes of non activity is detected and then switches (thus killing the light and its own supply). Motion detector does nowt til the light is switched on again cos it isn't powered. Must look at that more carefully...

 

[Taylortwocities]

a motion detector set up as a 2 way switch

Would require a changeover contact. That is something that a PIR doesn't provide. So you would need a relay with a C/O contact. Then its getting stupidly complicated...

 

[flameport]

3 LED downlights and an extractor fan (25w)

~40W total.
If those were left on for an additional 3 hours every single day, and the PIR saved all of that (it won't), it would cost you about £5 per year in additional electricity.
It will be years before you have even saved the cost of the PIR sensor.

The sensor will save a lot less, because it will have to be set to a moderately long time to avoid it switching off too soon, several minutes at least.
That means it will switch on for many minutes even if someone goes into the room for a few seconds.
It will also switch on in the daytime, wasting even more.

 

[Tigercubrider]

When I worked in a newly built building, the gents' loo had a sensor that operated as you walked into the room. Two urinals, hand drier and two basins. Further back, a single cubicle.
Every time you went for a crap, you went out of sight of the sensor.
Three mins after getting yourself seated, the room plunged into darkness
It took months to have it changed.

As said, led lights are so efficient that it's not worth it.
Only other alternative might be something like a hallway switch that pops off after 20 mins? Not sure if there is a cord operated version

 

[Tigercubrider]

http://mselectronics.co.uk/our-products/pctds2-pull-cord-time-delay-switch/

 

[Jackrae]

I thought you meant something fitted inside the WC pan to detect when a "Motion" had been performed

Apart from that, if someone is sitting there clocking like a hen, ie motionless, they may end up being plunged into darkness at a critical moment.

 

[EFLImpudence]

I thought you meant something fitted inside the WC pan to detect when a "Motion" had been performed

A dump switch.

 

[chivers67]

If there's a shower cubicle inside your bathroom the lights could go out if someone is in the shower too long

 

[Door7000]

To get around the night time tinkle issue I stuck these in all the bathrooms. It means anyone can go to the toilet at night without the need to turn on the lights and have the fan whirring up.

Sylvania Battery Operated Gizmo Wall Square Sense

It costs £5 including the batteries. They lasted about 3 months and then I replaced them with cheap alkalines.

They look great and you can position them where you want (double sided pads). If you have a big bathroom then put two in there.

 

[Door7000]

BTW, I also wondered if there was some kind of humidty sensor that could be use to turn the fan on when the shower is in use.

It seems stupid to have the fan on if someone is using the bathroom for non showering / hot bath duties so why can't the fan just turn on when it detects humidity?

For those who say it should also be on for toilet use courtesy then what about a methane sensor too?

 

[EFLImpudence]

There are all sorts of things you could do for whatever you want.

You could have a separate timer to disconnect the fan at night - and/or the light during the day if you have a window.

However separate ordinary light and fan switches allow you you to have the light and/or fan on whenever you want and turn either or both off whenever you want.