I have nice ceiling lighting in a room, in 2’ by 4’ fluorescent drop ceiling fixtures retrofitted to LEDs. But I have large low shelves over workbenches that cast a bit of shadow and want to add lighting under those, such as 2’ long LED strip units.
How can I make these come on and off when the main ceiling lights are turned on and off? I’m not sure it would be practical to add an outlet that is switched by the lighting circuit. I wish there was something like a photocell light control, but one which worked in the reverse sense relative to what people use for automatic outdoor lighting. I want the control to go on when it sees light, and off when it doesn’t. Of course I would place it somewhere the big ceiling lights illuminated brightly and the new under shelf lights hardly at all.
It depends.
If the room gets a lot of natural light, than, yes.
Even in those cases, it should be possible to put the photocell at the end of a straw, and point it at the overhead light, which should make it selective enough.
Or, if the overhead lights are LED, you could probably use their natural strobing to detect if they were on, but that makes the photocell circuit more complicated.
That’s what I’m asking for. I want a photocell-activated switch that turns ON when it DOES see light. All the ones I’ve found work in the reverse direction.
Do you know of a photocell-activated switch that turns ON with LIGHT?
That is the correct & code-compliant way to do this. (And might be simplest in the long run. Remember that the lifetime of home electrical wiring is measured in decades.)
You could connect such an outlet to either the ceiling lights, or to the wall switch for the lighting circuit. One of those should be feasible.
Another way: You could either replace the ceiling light switch with a smart switch or the ceiling lights with smart bulbs, and connect your undercabinet light strip to a smart outlet. You can program it so when one turns on both do, but you need to check to make sure that this programming will work with the hardware you chose, also the method you want to use to turn them on and off.
I’m going to second this. It exactly aligns with the functionality you want, without introducing potentially annoying quirks (i.e. they turn on if the room happened to be bright enough without the overhead). The whole “main switch triggers the overhead lights which triggers the light sensitive shelf lighting” seems a bit Rube Goldberg like.
OK, you have convinced me. I actually thought it might be against code to have a switch control both built in lighting and a receptacle. If this is correct and code compliant, it is clearly worth trying hard to do. I do like that wiring lasts decades, unlike the various home automation things I’ve tried and thrown away over the years. And I do like that this is not a quirky solution. Thank you!