Unusual use of M8/M9 to control a compressor

[ngwagwa]

Couple of caveats -

You don't 'need' to isolate the switch circuit. But doing so does no harm.

You'll be back - I reckon within a couple of weeks - to complain that, whilst under UCCNC control someone switched the compressor on accidentally, and after UCCNC has quit that the compressor has been left operating. That's a more complicated problem!

Doddy - is my circuit in post #5 feasible? If so UCCNC has control so the manual switches have no effect.

Regarding the compressor being left on I already have a signal lamp which comes on when the compressor is powered - this was put in before the 2 way switches as the compressor was often left running! The lamp is visible from our in workshop CCTV camera and we have a networked smart switch so the compressor can be turned off remotely

[Doddy]

Perfectly viable.

Although anything that bypasses the switches (e.g. my first post) takes the manual switches out of the equation. I'd look at the installation effort.

[ngwagwa]

Perfectly viable.

Although anything that bypasses the switches (e.g. my first post) takes the manual switches out of the equation. I'd look at the installation effort.

Thanks. As one of the 2 way switches is next to the compressor and power supply the installation effort is easy regarding mounting the relay, the wiring may take longer due to my electrical dyslaxia!