A/C unit and the power conductors "buzzing" in conduit on startup

[g-and-h_electric]

I think this topic has been discussed before, but I can't find it....... Anyway this is a newer install (less than 6 months old). The customer complaint is that on startup of the condensing unit the wires "buzz" in the conduit. It APPEARS that the unit is fed with #10 THHN , on a 30 Amp breaker.

I have not been to the site, as of yet, and am going by what the service tech sent me and told me.

In my opinion, the #10's are fine, the breaker needs to be the correct brand for the panel, and MY only thought would be a "SOFT START " kit for the condensing unit.

Am I correct????


Howard

 

[infinity]

There shouldn't be a problem with the conductor size or the breaker size. As stated the correct breaker for the panel should be installed. If I were on site I would check for the voltage drop at the unit on startup but given that the nameplate says that it will run on 208 with 240 volts applied VD shouldn't be an issue. Is it possible that there may be a problem with the unit?

 

[CoolWill]

It's probably not a problem, just an annoyance. If it is really bugging them, you can use #8 or #6 to damp the movement.

 

[g-and-h_electric]

The #8' s may be my solution. I was told that at one time TRANE had a service bulletin about this, and the suggested twisting the conductors.... Until I see it, or we ( as a group here) come to a consensus on that, I am not "going there"... 2#8 in 1/2 emt twisted, that could be fun!!!

I am heading to this on Monday, so I can report my actual findings then.


Howard