Rattling conductors in EMT conduit

[Structo]

How about #10 on a 30 Amp breaker?

That is what I was told to install for my heat pump.

[brentm]

If it's #10 wire on a 40 amp breaker , that is the reason why AC contractors should not be allowed to make their own runs. By NEC rules that is illegal. If it's #8 wire it's too big to go in a 1/2" conduit. Pulling it out and taping it to get it to stop rattling is a first for me in my 30 years of being an electrician. You should report the guy to your local building authority.

Thanks Passfan. I talked to our in-house electricians and they said the same thing you did, that the wire is undersized for that breaker.

Then I figured I'd ask Google... and found this link.

http://www.nachi.org/forum/f19/10-wire- ... er-c-1668/

I'm not sure now, if it's out of code or not????

[Structo]

That link won't open for me.

The name plate on the heat pump should specify the current requirements and possibly the wire gauge needed.

Most heat pumps only require about 20 amps to run.
The 30 amp rating for the breaker is for the start up current.