To determine the appropriate size breaker and wire for a 15-ton AC unit, you need to consider the electrical requirements of the unit. AC units typically have specific electrical ratings that dictate the appropriate breaker size and wire gauge. Here are the general steps to find the right size:
Check the AC unit's nameplate: The AC unit's nameplate or specification label should be located on the outdoor condensing unit. Look for the electrical information, which will provide the following key values:
a. Voltage: This is the operating voltage required for the AC unit. b. Amperage: This is the rated current draw of the AC unit.
Calculate the required amperage: Since you have the tonnage of the AC unit (15 tons), you can use a rough estimate to calculate the required amperage. Typically, 1 ton of cooling capacity requires around 1.2 kW of power. So, a 15-ton AC unit would require approximately 15 x 1.2 kW = 18 kW. To find the amperage, divide the power in watts by the voltage.
Amperage = Power (Watts) / Voltage (Volts)
Choose an appropriate breaker size: The breaker size should be equal to or slightly greater than the calculated amperage. Standard breaker sizes are available in multiples of 5 or 10 amps, so choose the next higher value. For example, if the calculated amperage is 60 amps, you would typically use a 65 or 70-amp breaker.
Select the appropriate wire gauge: The wire gauge should be chosen based on the calculated amperage and the length of the wire run. You will need to consult the National Electrical Code (NEC) or a qualified electrician to determine the correct wire gauge for the specific installation. Wire gauge is critical to ensure safety and prevent voltage drops.
Please note that these are general guidelines, and it is essential to follow local electrical codes and regulations. Working with electricity can be dangerous, so it's best to consult a licensed electrician for your specific installation to ensure compliance with local codes and safety standards.