Correct circuit breaker for small single phase pump motors

[mygoggie]

when you spec your contactors or relays be sure to use their AC3 ratings, not the AC1 rating.

Thanks for this wise piece of knowledge!

So for a 4A (at P₁ power rating of pump) the AC3 rating will be in the order of 20A to 25A. What will the thermal protection unit as fitted to the contactor be rated at?

This will obviously then be protected by a dual pole D-curve circuit breaker at which current rating? Just for interest sake, the pump manufacturer specifies a requirement of a dual pole circuit breaker with an air gap of 3mm or more between contacts.

I am learning a lot. Interesting!