Photocell

[Carlosfandango]

This might be glaringly obvious and I'm over thinking it but here goes. On a bill of quantities I received it asks for stair lighting to be controlled by a solar timeclock and a photocell. Will the photocell be energised when the timeclock switches so the lights are only on during the 'on' periods, and only if the photocell allows?

 

[Richard Burns]

Depends on the characteristics that the customer wants, the nature of the stairwell and the ambient light in the stairwell.

Generally if there is a high level of natural light in the stairwell then the photocell would be there to prevent the lights coming on in daylight.
The time clock would then be generally unnecessary but could just hold off the lighting until the customer thinks it should be dark, however this could lead to the lights not coming on when it is say stormy dark outside and lead to danger.

I would anticipate that the intent would be for the lights to only come on if the natural light was dim and have a timer rather than a time clock so that the lights went out after a period to save energy.

 

[Darkwood]

What he said^^^^