HVAC system circuit breaker.

You need 2 separate circuits, one for the air handler and one for the condenser, an air handler calling for 50 amp breaker means that they're installing an 8kw back up heater.
Service disconnects dont have to have a breaker, most often they just install a pull plug which is just an on/off switch. You have to run #8 wire to support the amperage for each unit.

My old system was like that, the new ones were different, far more efficient.

That's why I said he/we need to have details of exactly what he's installing before giving exact advice.
 
You will need 2 circuits. One for the air handler with the strip heaters, one for the condensing unit outside. You will have a disconnect outside at the condensing unit and unless the air handler is within sight of the electrical panel you should have one at the air handler as well. Service techs need a means of shutting off the power when working on the units. Not all disconnects are fused, in fact for hvac most are merely a switch of some type. Using type NM-B (Romex) cable, use #8 for the condensing unit with a 40 amp breaker and #6 with the 50 amp breaker for the air handler. They are rated for 40 and 55 amps, respectively. Usually the only time that the condenser and the strip heaters are on at the same time is at start up. This keeps it from blowing cold air while the compressor catches up.
 
You need 2 separate circuits, one for the air handler and one for the condenser, an air handler calling for 50 amp breaker means that they're installing an 8kw back up heater.
Service disconnects dont have to have a breaker, most often they just install a pull plug which is just an on/off switch. You have to run #8 wire to support the amperage for each unit.


T H I S

Yes, you need TWO circuits. The 50 amp circuit for the air handling unit will power the fan AND the ~8kW strip heat. The 40 amp breaker will power the condensing unit. Is this a mini split? Because 40 amps isn't large enough for a 5 ton condensing unit.....


You will also need to make sure you have ~100 amps of capacity outside your other loading that MOST LIKELY will be on at the same time the air handling unit fan, strip heat and condensing unit (in defrost mode) will be on.
 
Hillbilly my shop has two sub panels. One with 125 amp capacity and the other with a 60 amp capacity. I'm going to upgrade the other panel so both sub panels.have 125 amp capacity.
 
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