A 4 and 5-ton air-conditioner will likely need a circuit breaker rated 45-50 A connected with 8-10 AWG wire when supplied with 197-253 volts.
The breaker and wire size will largely depend on the power consumption (W) of the air-conditioner.
Older or less efficient units will likely draw more power and hence need larger breaker ratings compared to newer and more efficient air conditioners with the same cooling capacity (ton or BTU).
These ac units will likely be connected to their own dedicated circuit because of the large current draw (50-60 Amps).
Keep in mind though that these breaker and wire sizes are a guide.
You still need to check the manufacturer’s website or technical specifications manual to get the recommend breaker and wire size.
Central, window or portable air-conditioner wire and circuit breaker sizing
Unlike the smaller portable units, the central air conditioner and window units will likely have dedicated branch circuits with a breaker and wire gauge sized accordingly to both protect and prevent damage to the wire.
The guide applies to the larger residential central and window air conditioners with dedicated circuits.
Smaller portable air-conditioner units may likely use existing receptacles provided the wire and breaker are sized appropriately.
Using minimum circuit ampacity and maximum overcurrent protection to size circuit breaker
The minimum circuit ampacity and maximum overcurrent protection values help size the wire and breaker appropriately.
An excerpt of the electrical data for the Goodman GSXC16 air-conditioner is shown below.
To find the air-conditioner breaker rating: Use a breaker sized to the maximum overcurrent protection value, in this case, 20A. Use the specified minimum circuit ampacity value, in this case, 13.6 A to find the wire gauge.
Breaker rating vs minimum ampere rating
The air-conditioner breaker rating may be nearly double the manufacturer’s specified minimum amp rating. This can be quite confusing.
This is necessary because, at start-up, the air conditioner motors momentarily draw a large surge current which eventually normalizes to a lower value.
The higher breaker rating ensures that the air conditioner does not trip the breaker at startup.
Guide to sizing circuit breaker and wire gauges for air conditioners (with example)
To size, the wire and circuit breakers refer to the minimum amperage rating and minimum ampacity values in the electrical data section of your air conditioner.
- The breaker rating size should be set to maximum overcurrent protection value.
- To find the wire gauge, select a wire gauge that can safely carry the minimum ampacity values.
For example, using the Goodman GSXC16 air-conditioner’s electrical data above and following the guidelines 1 and 2 above, the breaker size should be 20A and the wire gauge 14 AWG.
Indicative wire and breaker sizes for 1.5, 2, 3, 4 and 5 Ton air-conditioners
Below are indicative breaker and wire gauge size for 1.5, 2, 3, 4, and 5 ton (18,000, 24,000, 36,000, 48,000, 60,000) BTU air conditioners respectively based on the Goodman series. Always check the electrical data for your specific air conditioner model.
|No||Capacity (ton)||Capacity (BTU)||Manufacturer minimum amp rating (A)||Breaker rating (A)||Minimum wire size (AWG)|