Electrical – Power 240 v ac light from two power sources

electrical

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?

Best Answer

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.

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