A/C breaker size

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prayerpartner212

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Owensboro, KY USA
I have an A/C that says on the name plate 20 Amp Max, and I installed a 30 Amp breaker on #10 wire. The inspector said I can only use a 20 Amp breaker????
I understand that the breaker size is designed to protect the wire not the equiptment correct????
 
protects both. The equipment was likely listed to be protected by a 20m am p breaker and you can not exceed that rating 440.22(C)
 
prayerpartner212 said:
I have an A/C that says on the name plate 20 Amp Max, and I installed a 30 Amp breaker on #10 wire. The inspector said I can only use a 20 Amp breaker????
I understand that the breaker size is designed to protect the wire not the equiptment correct????
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The A/C unit should have the following on the nameplate:

MCA- minimum circuit ampacity. This is the minimum conductor size.
MOCP- maximum overcurrent protection. This is the maximum breaker size.

If the A/C says MOCP is 20 amps, that is the largest breaker that can be used.
 
The breaker is protecting the equipment, it is also the conductors from ground fault or short circuits conditions, not overload. The inspector was correct, the fact that you used larger conductors than required does not matter when sizing the OCPD according to the nameplate.
 
prayerpartner212 said:
I have an A/C that says on the name plate 20 Amp Max, and I installed a 30 Amp breaker on #10 wire. The inspector said I can only use a 20 Amp breaker????
I understand that the breaker size is designed to protect the wire not the equiptment correct????
Click to expand...

The MOCP for HVAC is already oversized from the factory to take into consideration compressor inrush and start-up current. The MCA (minimum circuit ampacity) for that unit is probably somewhere between 12 and 18 amps. As stated by others, MOCP, or maximum overcurrent protection, is just that... Maximum size breaker or fuses you can use on the unit.

At least changing the 30 amp 2 pole breaker for a 20 amp 2 pole breaker is a pretty quick and cheap fix. You also have to pay attention to whether or not the manufacturer requires breakers, fuses, or both... Some of them must have fuses...
 
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