Dusk till Dawn photocell

[bjnorris]

Hi, I Last year. I installed a dusk till dawn switch, with a built in timer, to control all of my outside lights and pond lights. This works as it should they come on if it's still dark at 7am and they come on in the evening as soon as it's dark and go off around 11pm Great!
However there has been a few occasions (Noises outside, or if i've forgot to put the bins out in time) were I'd like to be able to activate them manually after the 11pm curfew.

Now I was thinking of just providing a link via a switch to bypass the optic sensor, but I'm not sure if doing this may damage the photocell? Would it work or be better to use a relay were the N/C contacts are wired as they should be and the N/O contacts be the new + feed via a switch that would activate the relay? Or is there a better method.
Brian

 

[oldbutnotdead]

Have you still got the instructions from your photocell? Some of them have an override mode (if you switch the supply off then on again quickly the load/whatever will come on and stay on til you cut the supply for a longer period (30 seconds or so).

Failing that, 2 way switch with load as common, perm live as L1 and switched live from photocell/timeclock as L2 will work safely under all circumstances. Make sure the permanent live is from the same circuit as the supply to the timeclock and photocell (if necessary use 4 core flex to bring the whole lot into your switch as a lump).

 

[bjnorris]

Now why did I not think of that!
Switching the supply off and on quickly is a no no. As this will re-set the timer again and it takes a few days before it works out what time it should shut off at night
(Don't ask me how it does this but it even adjusts to GMT & BST after a few days?)
However by using a two way switch as you describe, isolates the perm live from the timer when switched, and still leaves the live going into the timer to keep the clock happy.
It's so simple it's brilliant. Thank you for that.