Many people ask for the maximum number of outlets on a breaker. The answer is more nuanced than the common "8 per 15 A circuit" rule of thumb.
What the NEC says
For dwelling units, the NEC does not limit the number of general-purpose receptacles per circuit. Instead, the load calculation in Article 220 assumes 3 VA per square foot for general lighting and receptacles, and circuits are laid out to serve it. For non-dwelling occupancies, NEC 220.14(I) counts each receptacle outlet at 180 VA.
A simple calculation
A 15 A, 120 V circuit has 1,800 VA of capacity, and a 20 A circuit has 2,400 VA. Dividing by 180 VA per outlet gives:
- 15 A circuit: 1,800 ÷ 180 = 10 outlets
- 20 A circuit: 2,400 ÷ 180 = 13 outlets
If the load will be continuous, apply 80% first: 1,440 VA ÷ 180 = 8 outlets on 15 A, and 1,920 VA ÷ 180 = 10 outlets on 20 A. That is where the common rule of thumb comes from.
Practical limits
- Plan for the real loads, not the outlet count. A single space heater can use a whole 15 A circuit.
- Keep known high-draw items (microwave, window air conditioner, vacuum) on dedicated or 20 A circuits.
- Leave margin for future use; circuits regularly operating near their rating are more likely to trip.
Dedicated circuits
Some loads require their own circuit, such as the dishwasher, microwave, garbage disposal, freezer and fixed space heaters, depending on the manufacturer's instructions and local code. Check the nameplate and installation manual.
Always confirm local amendments with your authority having jurisdiction before wiring.
Try the calculators
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