On Wednesday, 24 April 2019 10:32:29 UTC+1, tim... wrote:
My new abode is in a block of flats that has interior lighting provided by
(60) bulkhead lamps

If the bulkhead lamps have a conduit knockout available you can probably fix a surface mount detector adjacent to it eg

https://www.danlers.co.uk/pir-occupa...tch-ip66-rated

or

https://www.danlers.co.uk/microwave-...90-damw6a-ip67

They also do ones with step-down illuminance for various ballasts and dimming systems eg

https://www.danlers.co.uk/pir-occupa...wn-illuminance

and custom manufacturing, so with potentially 60 units to modify - unless they are wired in groups - it might be worth contacting them.

https://www.danlers.co.uk/oem-produc...pancy-switches

Owain