Q. What are the requirements when installing 15A, 125V duplex receptacles on a 20A, 120V circuit?

A. There are many rules found in 210.21(B), which covers receptacle ratings and loading. A single receptacle on an individual branch circuit must have an ampacity not less than the rating of the overcurrent device. FPN: A single receptacle has only one contact device on its yoke [Art. 100]. This means a duplex receptacle is considered two receptacles.

Where connected to a branch circuit that supplies two or more receptacles, the total cord- and plug-connected load must not exceed 80% of the receptacle rating. A duplex receptacle has two contact devices on the same yoke [Art. 100]. This means even one duplex receptacle on a circuit makes that circuit a multi-outlet branch circuit.

Where connected to a branch circuit that supplies two or more receptacles, receptacles must have an ampere rating in accordance with the values listed in Table 210.21(B)(3).