PERMISSIBLE LOADS ON BRANCH CIRCUITS BASED ON NEC BASICS AND TUTORIALS

The NEC is very specific about the loads permitted on branch circuits. Here is a recap of these requirements.

• The load shall not exceed the branch-circuit rating.

• The branch circuit must be rated 15, 20, 30, 40, or 50 amperes when serving two or more outlets, NEC 210.3.

• An individual branch circuit may supply any size load.

• 15- and 20-ampere branch circuits

a. may supply lighting, other equipment, or both types of loads.
b. for cord-and-plug-connected equipment, shall not exceed 80% of the branch-circuit rating.
c. for equipment fastened in place, shall not exceed 50% of the branch-circuit rating if the branch circuit also supplies lighting, other cord-and-plug-connected equipment, or both types of loads.

• The 20-ampere small-appliance circuits in homes shall not supply other loads, NEC 210.11(C)(1).

• 30-ampere branch circuits may supply equipment such as dryers, cooktops, water heaters, and so forth. Cord-and-plug-connected equipment shall not exceed 80% of the branch-circuit rating.

• 40- and 50-ampere branch circuits may supply cooking equipment that is fastened in place, such as an electric range, as well as HVAC equipment.

• Over 50-ampere-rated branch circuits are for electric furnaces, large heat pumps, air-conditioning equipment, large double ovens, and similar large loads.