Replace normal switch with pir switch

[SUNRAY]

Sounds like I'd have to get someone in to do that. I'm thinking I'll try the switch you've suggested first.

You are unlikely to find all the wiring you require at the light but it is all at the fan isolator switch (or at the fan if there is no isolator switch).

 

[pcaouolte]

the problem I'm trying to solve is that the light is constantly left on. Any other suggestions?

Stick an LED lamp in the light. A PIR switch will use power 24 hours a day for the sensor circuit. You might as well use that power for the LED lamp and hope that sometimes people will switch it off.

 

[Taylortwocities]

Stick an LED lamp in the light. A PIR switch will use power 24 hours a day for the sensor circuit. You might as well use that power for the LED lamp and hope that sometimes people will switch it off.

You crazy person. I did a bit of research. Data shows that

PIR motion sensor, power consumption is approx 40µA​

That’s tiny compared to an LED.

 

[SUNRAY]

You crazy person. I did a bit of research. Data shows that

PIR motion sensor, power consumption is approx 40µA​

That’s tiny compared to an LED.

That's changed a lot in the last dozen or so years, one office block I worked in had ladies and gents toilets on 5 floors with 4 or 5 CFL's in each. As a cost saving exercise they fitted 3 or 4 PIR's in each (due to layout) to prevent the lights being on for about 12 hours a day 5 days a week. IIRC in those days PIR's were about 2W so about a constant 90W 24/7 added. Sadly the lights were on for a substantial period every day due to the regular users and the energy consumption rose considerably.

 

[pcaouolte]

You crazy person. I did a bit of research. Data shows that

PIR motion sensor, power consumption is approx 40µA​

That’s tiny compared to an LED.

But the LED can be switched off most of the time and will then consume nothing. The OP really only seems to be trying to prevent the light being left on accidentally.