![]() ![]() The outdoor unit should specify the MCA (Minimum Circuit Ampacity) and MOCP (Maximum Overcurrent Protection) on its plate. The minimum ampacity helps determine the minimum gauge wire you need to use.įurthermore, we have provided tonnage table charts below if you are a visual person and need a better reference. Wire gauges are measured in diameter based on the American Wire Gauge (AWG) chart. If you have your average 240 volts 2 kW air handler, you will need a 30 amp breaker and a #10 electrical wire. Let us say you have a 2-ton heat pump at home. ![]() That information also provides you with the maximum overcurrent protection or MOP rating. In return, it makes it much easier to determine what size breaker you need. If you are still unsure how to follow this guide, you can quickly look at the nameplate data on the outdoor unit. Not only that, but the amount of voltage the heat pump needs also determines the size of the breaker. What Wire Size and Breaker for Heat Pump? (Tonnage Chart)ĭepending on the size wire, you’ll need to find the breaker’s size, which gives you the specific rating. Given that information, the main power panel has two separate breakers for the air handler and the other one for the heat pump condenser. A regular heat pump requires two dedicated branch circuits: the condensing or AC unit and the air handler. It is essential to know how many breakers you will need for a split heat pump or central AC in the first place. Keep reading to find out more information and what wire and breaker sizes are needed for your central cooling system. Manufacturers list the maximum breaker size on the data plate located on the side of both units. So a final note when inspecting AC units wired with NM cable, conductors are sized to the MCA and the OCPD cannot exceed the MaxOCPD listed on the nameplate.The wire size and breaker for heat pumps and air conditioners (AC) vary based on the tonnage. However, one might wonder how many amp breakers you need for a heat pump.Ī split heat pump or air conditioner has two separate electrical circuits, one for the outdoor unit (condenser) and the indoor unit (air handler or furnace). The main electric panel contains two different amp breakers one for the indoor unit and the other for the heat pump condenser or air conditioner. MCA=25 amps, MaxOCPD= 40 amps you could have piece of conduit feeding the AC unit with #12 THHN conductors and a 40 amp OCPD protecting the curcuit. Some of this seems strange because it violates what we consider to be the normal way conductors are protected ( #14-15 amps, #12-20 amps, #10-30 amps, etc.).Īnd there are other factors that make this even more complicated, for example #12 conductors are normally limited to 20 amps but for motors and AC units their ampacity can be 25 amps according to T310.15(B)(16) when a few other variables are met. ![]() The OCPD can be any size between the MCA and the MaxOCPD. This is permitted because the conductors are protected from overload by the overload device within the compressor. The MaxOCPD can also be used to size the OCPD and is often larger than the ampacity of the conductors. The MCA is used to size the conductors and the minimum size OCPD for the branch circuit. ![]() When sizing conductors for AC units the NEC requires you to use the nameplate data (if available) to size the conductors and the OCPD. Overload protection is provided by the overload device that is integral to the compressor.Īccording to the NEC overload protection is typically set at 115% of the motor FLC, the conductors feeding at motor are sized at 125% so the overloads will protect the conductors from overcurrent. For an AC unit the OCPD provides the conductors with both ground fault and short circuit protection, it does not provide overload protection. So a 40 amp breaker better have at minimum #8.Īs others have stated this is incorrect. So who cares what it operates, that’s for the installer to decide, what we care about first is what size wire they used and does the OCPD protect that wire. Breaker does not protect equipment, OCPD fuse or breaker in a load center is protecting the wire feeding the equipment. ![]()
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