Richard Burns possible method provides the control:
If[K or P or T] then L is on.
Or in prose:
If it is dark or if it is the right time the lighting will turn on; and their is the option also to use the keyswitch to manually turn the (non-emergency) lighting on .
The light fittings each have their own keyswitch to test each fittings integral emergency lighting.
'Or' requires switches in parallel and 'and' requires switches in series. Using 'brackets eg [ ...]' one can state clearly the
hard-wired combinational logic required from the switches (as was done in #6 using () and [].
So how would one write down as if/then and then implement:
The non-emergency lighting is to turn on:
1. if it is dark and it is the right time,
or
2. a manually timed override (eg using a time-lag push switch - see
Vacuum Time Lag Light Switch - https://www.tlc-direct.co.uk/Products/EK400A.html)?
or
2. Manually using a keyswitch.
![[ElectriciansForums.net] Lighting circuit controlled by a time clock and photo cell through a contactor](https://electricians.s3.eu-west-1.amazonaws.com/data/attachments/29/29814-89b2424f33818fbfce6fb6d785517822.jpg "[ElectriciansForums.net] Lighting circuit controlled by a time clock and photo cell through a contactor")
