Help sizing furnace and heat pump circuits

[crtemp]

I have an electric furnace that draws 52 amps at 240 volts.
I also have a heat pump that says it needs a minimum 20 amp max 25 amp breaker.

Do I have to size my furnace wire any bigger than 52 amps?
Can I just pull a 12-2 to my heat pump? Not sure if I have to do 125% of the nameplate or not.

Thanks

 

[augie47]

Both should have a nameplate (Code required) giving you the MCA (minimum circuit amps) to size your conductor and the MOCP (maximum overcurrent protection) to size your overciurrent device.

 

[kwired]

I have an electric furnace that draws 52 amps at 240 volts.
I also have a heat pump that says it needs a minimum 20 amp max 25 amp breaker.

Do I have to size my furnace wire any bigger than 52 amps?
Can I just pull a 12-2 to my heat pump? Not sure if I have to do 125% of the nameplate or not.

Thanks

I agree with Gus, what does nameplate MCA say? MCA determines conductor size not the min/max overcurrent protection device marked on nameplate. That heat pump with a max breaker of 25 likely only draws somewhere between 10 and 15 amps and the MCA is likely low enough that you could even run 14 AWG conductors.

Pay close attention with the 52 amps on the furnace. If running NM cable,you must use 60 deg ampacity table. If 52 is your MCA you are still OK with 6AWG. If 52 is the actual current and MCA is higher than 55 then 6AWG is too small @ 60 deg.

 

[crtemp]

I am using type SE cable #6 copper. The wire I'm using is good up to 55 amps. I'm pretty sure that the MCA was 52 amps. Sounds like I should be good then.

Thank you for the explanation.