Wire Size For A 60 Amp Breaker ,.According To The NEC ??

[Grumpycat]

#2 Aluminum fits in my 50A breaker. I use it to charge my Tesla.

 

[3Ts]

The purpose of a breaker is to protect the wire, not what is connected to the wire. The name plate ratings that list the amps are so the installer will know what size wire to use based on the distance.

So, if you have a 60 amp breaker, the wire had better be able to handle 60 amps. I made my builder open up a wall because he tried to tell me that 40 amps on a #12 wire was ok. (#12 wire = 20 amps, but long distance will reduce this)

 

[Mat4644]

The manual will state the incoming requirements of the unit. Most likely if 10 is used as a transition no high amp requirement. If you want to be code compliant rip out the old wire and breakers and install per new requirements. Common to have high and low amp separate feeds.

Correct way to use old wire is to go to a small sub panel with breakers at the furnace instead of a disconnect. From the sub panel install the correct breaker and #10 wire to furnace. This way correct protection is provided for wire sizes. Small sub panels are low cost.

 

[CADplans]

Are you sure that the AC unit has breakers in it,
many of the newer disconects look like breakers but are not.
QO2TR - Square D QO2TR - 6A Non-Fused A/C Disconnect w/ Top Open (24V)
I could see your concern about a future electrician not checking the complete circuit out before replacing a breaker,
how is the old cable terminated in the original breaker panel to what size breaker.
Most of the time a 30 amp breaker does not have a lug capable of accepting #2 wire wire,
many will take a #8 as a maximum, unless it is given a haircut which is not a recommended procedure.

I first looked at the air handling unit, and the breakers are labeled "60 AMP" right next to the trip handle. , so yes, I am sure they are breakers.
I would have assumed, if Trane wanted the devices as convenience disconnects, they would have installed NON-FUSED ones.
Surely, the NON-FUSED device would be cheaper,,

Then , another service concern possibility ,,
My air handler goes bad in 3 years, post lottery winnings,,

The new guy goes to connect the replacement air handler,,
There are two 220 volt incoming wires, unlabeled, as to purpose,, and two identical 60 amp breakers.
The installer swaps them, connecting the #10 to the emergency backup,, and the larger wire to the identical 60 amp breaker that only powers the fan,,

Two months later, on a EXTREMELY cold night, the emergency heater comes on,, the #10 wire heats up and looks like the inside of a toaster,,,

 

[kcflhrc]

Not only NO but **** NO. You have to size the wire to the breaker. Why you ask? Because the 10 gauge wire will melt before the 60 amp breaker trips.

You can however go the other direction where you use a #6 wire on say a 20 amp breaker, but once again, do it right.

 

[Budweiser John]

Install sounds like a hack job to me.
Was a permit pulled and the final install inspected?
I would think your local electrical inspector should have a look.
One thing for sure, a 10 Gauge wire has no business being down stream of a 60 amp breaker.

B. John

 

[LouNY]

No weres in this thread is the ampacity of the circuit breaker in the main panel feeding this setup mentioned!!!!!!

 

[CADplans]

No weres in this thread is the ampacity of the circuit breaker in the main panel feeding this setup mentioned!!!!!!

You are correct,, that panel is un-labeled, so, I will not know what the breaker is until I remove the cover, and trace the wires.

 

[Mat4644]

When all else fails read the manual.

Not being sarcastic. What are the requirements of the unit and then look at the situation.

 

[CADplans]

When all else fails read the manual.

Not being sarcastic. What are the requirements of the unit and then look at the situation.

I have just been doing that,,
the installation manual says,, see the info on the unit,,
the installer did not apply the heater info on the unit,,