High amperage relay to control hot water heater, baseboard heat and misc other stuff

I am trying to fnd a 240v relay that can handle 20 to 40 amps. Would like a latching relay or even better, one with local control so that if the automation system dies, the loads can still be controlled. Anyone have suggestions on a product. I searched but am not sure what to buy …

With loads like that you’re best rolling your own.

Disclaimer:with loads like that you’ll likely cause a fire if done wrong.

I would use a sonoff to drive a contactor which is designed for the load. You then have the option to include a switch in parallel with the sonoff to manually turn the contactor on.

If you need a diagram I can a bit later.

Something like this is good https://www.screwfix.com/p/british-general-40a-dp-contactor/1836p

This should work for you:


That’s a nice option Chris. I did not realise there are higher power ones.

I wonder if one can flash it with custom firmware.

Found another option on AliExpress

Easy to control with an ESP8266.

However, I would really like to find a latching relay.

Have you considered Thristor load switching rather than relays?