I have existing led lighting in my garage 240 v ac which operates from a pull switch. My garage door opener provides a facility to power a light with 240 v ac as well. What if any additional circuitry, if any, would I need to add if I connect the garage door opener to the same light to cover the situation where both supplied power at the same time?
If I've understood correctly, you want the existing lighting to turn either when the pull switch is activated or when the door opener is activated.
To accomplish this use a relay. The relay's coil would be powered by the door opener and the relay's switch terminals would connect to the terminals of the existing switch. In this way the light will be powered from its existing source whenever the pull switch or the relay (or both) are activated. The relay protects against a variety of bad results that could occur if the door opener output had been connected directly to the pull switch or lighting.
You'll have to choose a relay with appropriate voltage and current specs, and consider local requirements and customs to choose a junction box to contain the relay and wiring. I'd suggest that the relay should be located as near to the pull switch as possible.
Greg has the crux. I'm only going to talk about packaging.
I gather the pull switches are inside the LED lights. I would modify each LED light as follows:
I would affix two-terminal low-voltage screw terminal blocks to the outside of each LED light, and put a label that says "Apply 5 VDC to bypass pull switch and turn on light".
I would get a 5V relay with contacts rated for tungsten load at least as large as your LED light (1 amp should suffice).
The coil of the relay is wired with #18 wire to that external terminal block.
The "NO" contacts of the relay are wired to both sides of the pull switch, so it is in parallel with the pull switch.
- Now if you apply 5 volts to the external terminals, the light comes on.
At the garage door opener, I would unscrew the light. Then I would install a common "Edison E26/27 to NEMA 1-15R" screw-in adapter that turns a light bulb socket into an appliance socket. Then I would install any common cheapie USB cell phone charger block that works on 100-240V and yet has a NEMA 1-15P plug into that adapter.
I know I'm sending you on a snipe hunt to find NEMA 1-15 gear, but NEMA 1 is the only mains socket that will fit inside an Edison E26/27 socket.
As of now, when the garage door turns on the light, you can charge your phone LOL.
Then I would get any competent USB cable and cut it midway. Find the wires which connect to the outer two USB terminals. Splice those to #18 thermostat wires, and distribute that to each of the LED lights.