Hi

I am from Australia and have a Panasonic Inverter Split System AC in my unit.

Recently I have noticed that when it is turned on, there is a buzzing coming from the circuit breaker, and the circuit breaker box becomes (worryingly for me) warm.

When the AC is turned off, it cools down and buzzing stops.

I have been having the bathroom and kitchen renovated as well, and they have been doing a lot of electrical work (adding new powerpoints, fixing a broken circuit after they drilled into the wiring, etc). But the AC has its own circuit! And I never heard this buzzing before the work started. So I pointed it out and he changed the circuit breaker while I was at work.

Anyway, that has made no difference. It is still buzzing and warm.

Is this something I should be worried about, and what can be done? This builder electrician did not seem too interested in helping!

Thanks
Matt

A breaker that starts buzzing usually indicates a failing breaker... you say a new one has been installed with same result. If you have the tools and only if you're also comfortable with testing, check the unit to verify you have the correct voltage at the split system input terminals, using an amprobe verify the current draw is very close to that given on the unit nameplate... Verify the circuit breaker is the correct size...
I would hope one of these tests could give you a clue to the problem,
Good luck, be safe