Lighting circuit controlled by a time clock and photo cell through a contactor

[marconi]

May I prompt further discussion? What should one have asked before taking on this job? Specific questions please on the required control not generalities. A brains-trust to arrive at a good practical, cost-effective solution.

Brains trust see: The Brains Trust - Wikipedia - https://en.wikipedia.org/wiki/The_Brains_Trust

 

[Richard Burns]

As said there is too little control information available to make a reasoned response.
This is one possible method of achieving a control method, but this may not be the control required or compliant with standards.

 

[marconi]

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.