are amps split over two conductors?

Thread Starter


Joined Dec 1, 2011
I am trying to figure out if I need to run new wire to my new heat pump. It shows 28amps ampacity with 40 amps min and 45 amps max...

We ran 10/2 to it. the brkr makes a slight humm when it starts. no brkr pop. My question is does the amp draw split in half over the two conductors of 110v each or does it remain the same over both. IE 14 amps versus 28 amps. I know the amount of Watts is halved when you run 220 v versus 110v.

Charts show ampacity for #10 wire at 55, so I believe I am okay???



Joined Feb 19, 2009
Are both conductors carrying the live power, or is one the return?

If the wire warms up any during operation, then you need larger wire, or another one put in parallel with the one you just ran, the current will split evenly between them. Well, roughly evenly, some wires have a milliohm or two more resistance, and won't take exactly half of the current, but very close to it.

What is the distance of this cable run? The longer the run, the more critical the capacity is. 10Gauge is rated for 40 Amps, but could do 48 Amps for short periods, such as a 2 second startup, though I wouldn't recommend a continuous 40A through it.

An electrician in your area would be able to help out more since we are unable to see the exact setup and how your breaker panel is configured, I'm assuming this is a 220V run?


Joined Oct 15, 2009
Assuming identical cable length/size/resistance,etc.. the current will split 50/50 with parallel conductors. However I don't think you have parallel conductors (if you did you would have 2 runs of 10/2 not 1 run). You just have a hot and a neutral. This is called a circuit NOT a parallel conductor connection.

Not sure what "charts" you are using nor what country you are in but in the US the national electrical code book table 310.16 lists 10 AWG wire with 75 deg C connections/insulation at 35 Amps.. And you also didn't list what size breaker is feeding this heat pump.. That will dictate wire size.

You typically should follow the installation instructions for your heat pump as well as applicable electrical codes. Failure to do so can result in a fire...
Please find a qualified electrician..