30amp?

[nbhi]

At todays inspection the heat pump/AC unit stated max amp of 20.
When we inspected the panel, there is a 30amp breaker with 10awg.
supplying the AC. Is this installed incorrectly or is it just over kill for protection?

[nbhi]

Forget I asked fellas. I found a thread that Mr. Pope responded to.
There is a OCPD at the disconnect.

[Robert Meier]

Since your disconnect had the proper size OCPD you're good.

In general HVAC units should have a minimum (MCA) and a maximum (MOCPD) written on their nameplate. The conductors can be sized to the MCA, the overcurrent protection device can be sized anywhere between the MCA and the maximum listed on the nameplate. The conductor size does not have to correspond to the size of the OCPD since it only provides short circuit and ground fault protection.

For example, a unit with a 19 amp MCA and a 30 amp MOCPD can use #14 conductors on a 30 amp breaker and be code compliant.

[Frank L. Bartlo]

Couldn't the current fry the motor of the AC unit, or somehow otherwise overload it, if a 20A max is stated for the unit itself?

Seems to me 10 gauge wiring with a 20A circuit breaker would be "overkill for protection," and perfectly fine.

[Mathew Hawley]

This is how I word oversized breakers on AC units.

The AC condensing unit's data plate calls for a maximum fuse size of 20-amps and the unit is currently fused on an 30-amp breaker. This condition can void the manufacturer’s and may not provide the proper over-current protection for the unit.

[Robert Meier]

Originally Posted by mhawley

This is how I word oversized breakers on AC units.

The AC condensing unit's data plate calls for a maximum fuse size of 20-amps and the unit is currently fused on an 30-amp breaker. This condition can void the manufacturer’s and may not provide the proper over-current protection for the unit.

I like Mathew's idea. For accuracy I would just change a few words. Since this unit is protected by a circuit breaker I would change the word fuse to circuit breaker or Over-Current Protection Device. In the second sentence change over-current protection to ground fault and short circuit protection. In this case the circuit breaker does not provide over-current protection, that is provided by the overloads integral to the unit.