The right breaker size for a condenser is approximately twice the RLA (Rated Load Amperage, which is the amperage it draws while running and after the start-up surge). RLA amperage varies between units, with older condensers and less efficient ones drawing more amps. So, for example, a 3-ton condenser can have an RLA that ranges from approximately 14 to 18 amps, requiring a 30, 35, or 40 amp breaker—and there is no one-size-fits-all breaker for any 3-ton condenser.

   The correct breaker size is always listed on the data plate at the side of the condenser. Some manufacturers specify both a minimum and maximum breaker size, and others just give the maximum breaker. Here’s two examples below.

    Because a new condenser installed to replace an older one will often have a lower RLA and maximum breaker rating, it may be necessary to change the breaker in the panel, based on the manufacturer’s spec.

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  To learn more about heating and air conditioning systems, see these other blog posts:

• How can I find out the SEER of my air conditioner? 

• My air conditioner won't turn on. What's wrong? 

• How can I find out the size of my air conditioner? 

• How can I tell whether the condenser (outdoor unit) is an air conditioner or heat pump? 

• Where is the air filter for my central air conditioner and furnace? I can’t find it? 

• Does an old air conditioner use more electricity as it ages? 

• How did homes stay cool in Florida before air conditioning? 

• What is wrong with an air conditioner when the air flow out of the vents is low?

• Why has the thermostat screen gone blank? 

• Why does it take so long to cool a house when an air conditioner has been off for a while? 

• Why is my air conditioner not cooling enough? 

• What are the most common problems with wall/window air conditioners?  

• Will closing doors reduce my heating and cooling costs? 

   Visit our HEATING AND AIR CONDITIONING and ELECTRIC PANELS pages for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.