Electronic – 230V/230V AC relay circuit


I've built a nice programmable switch basing on Raspberry and a relay board. It's fine for driving common 230V appliances but the relays seem rather flimsy; I wouldn't trust them to run 10A of current through them. I'd like to connect devices that potentially take about much – heaters for my home etc. The obvious solution is next stage relay rated for currents of that order; 230V input from my switch, 230V over some thick wire from a rated socket, the load on output of the relay.


simulate this circuit – Schematic created using CircuitLab

What I'd like to ask – is that enough? I know driving the relay driven by logic pin requires quite a bit of "glue electronics", an optocoupler, a transistor to amplify signal from the optocoupler, protecting diodes, resistors regulating the levels etc. Is anything of that kind required when driving one 230V relay from another? Any extra electronics between them, or can I safely connect them directly like in the schematics above?

Best Answer

Yes. The first relay effectively isolates the Pi from any mains so no need for opto isolator. The switch rating of the first relay is sufficient to switch the current through the coil of the second so no need for amplification. The only point I would make is that the second relay should be of an AC coil type.

see http://www.ehow.co.uk/about_6498402_difference-ac-dc-relay-coil.html