Powering a 240v fridge with a 2 channel relay

Thanks for that.

To clarify, by 'isolated from mains' you mean a power source that is not coming from the home AC? If I was using an AC to DC adapter to power the Arduino that would be undesirable? If I was using a phone USB AC adapter and powering it from the USB that would also be a problem?

I was considering powering it via a 9v battery so I could do that if a safer option.

I forgot to mention that Earth really means exactly that. Here in the US, the ground connection for the mains entering a home is connected to an eight foot long copper plated steel rod driven into the earth. All grounds are connected to that rod.

Isolated means a typical power supply which contains either a 50/60hz step down transformer or a switch mode power supply where the transformer runs at perhaps one hundred kilohertz. Both types of power supply provide infinite resistance measured between the input to output sides.

Both types of supplies you mention are fine, you do not have to resort to batteries to power an Arduino unless it is portable.

I hope the original participants are still monitoring this topic. I found out that each fridge compressor is actually labelled as to how much its inductive load is. In my case my fridge draw ±1Amp normally but it's rated to draw 6Amp during startup. Wouldn't a 10Amp rated relay then be good enough to use? Will it still wear out too quickly? If so, what about using 2 in parallel just to be safe?

Paulnaude01: I hope the original participants are still monitoring this topic. I found out that each fridge compressor is actually labelled as to how much its inductive load is. In my case my fridge draw ±1Amp normally but it's rated to draw 6Amp during startup. Wouldn't a 10Amp rated relay then be good enough to use? Will it still wear out too quickly? If so, what about using 2 in parallel just to be safe?

I happened to see this and as one of the originals, wonder why you resurrected it?

NO two or more electrical-mechanical devices will operate at the same time. Even DPDT relays. So each contact must be capable of carrying the full load. A SSR would be the only reasonable answer.

Paul

Paulnaude01: normally but it's rated to draw 6Amp during startup. Wouldn't a 10Amp rated relay then be good enough to use?

A 20 amp relay won't be very much dearer. And IIRC there are relay specially suited to inductive loads for domestic appliances. Check what is available from one of the bigger component suppliers (not in China or Ebay :) )

...R