15 Amp vs. 20 Amp GFCI Outlets: What's the Difference?

Do you need a 15 amp or 20 amp GFCI outlet? The answer depends on the branch circuit, the equipment being powered, and the type of receptacle the application requires.

TL;DR: Both 15A and 20A GFCI outlets provide ground-fault protection. The main difference is their amperage rating and receptacle configuration. A standard 15A GFCI uses a NEMA 5-15R configuration, while a 20A GFCI uses a NEMA 5-20R configuration with a T-shaped slot that can accept 20-amp plugs.

Before replacing a receptacle, check the circuit and connected equipment instead of choosing a higher-amperage GFCI simply because it sounds more powerful.

According to National Electrical Code, only a 15-amp or 20-amp electrical receptacle can be installed to a 20-amp circuit. A 15-amp receptacle may also be installed on a 15-amp circuit. However, a 20-amp GFCI outlet may not be installed to a 15-amp circuit.

If you are looking to install a 15-amp outlet, make sure:

1. The electrical receptacle is UL Listed
2. The outlet features feedthrough wiring so it can be installed to a 20-amp circuit

20-amp circuits are designed for a heavier load of electrical current than 15-amp circuit breakers. For commercial and industrial power distribution, the circuit breakers will have a higher amperage.

For commercial spaces, the NEC requires that each outlet be measured at 180 volts per amp, or VA. If you want to calculate how many outlets can be installed on a 120 volt and 20-amp circuit, its simple. Lucky for you we took the math out of the equation and made this chart. You’re welcome!

The general rule of thumb is to never exceed a max load of more than 80%. Lighting, for example is normally run on a 15-amp circuit. This helps allow for growth and any changes in the load size. For this reason, lights and electrical outlets should be on separate circuits to allow maximum loading of lighting circuits, and maximum capacity for outlets.

According to the NEC, although there is no limit on the number of lighting and/or receptacle outlets on dwelling general-purpose branch circuits, it does require a minimum number of circuits to be installed for general-purpose receptacles and lighting outlets [210.11(A)]. In addition, the receptacle and lighting loads must be evenly distributed among the required circuits.