Why not? Some homeowners still think that you can put a 20 amp outlet on a 20 amp circuit. It seems quite reasonable, right? A 20 amp circuit is designed to handle 20 amps, that’s true. But no electrician will put a 20 amp receptacle on a 20 amp circuit.
This brings us to two questions, namely:
- Why can’t you put a 20 amp outlet on a 20 amp circuit?
- Can you put a 15 amp outlet on a 20 amp circuit? That is without running the risk of the circuit catching on fire.
In short: Because of the NEC 80% rule and, yes, you can put a 15 amp outlet on a 20 amp circuit. Let’s explain why this is possible:
A 20 amp circuit is designed to handle 20 amps. But, for safety reasons, NEC (National Electrical Code) states that you can never load the circuit more than 80% of its total ampacity.
Note: This is true for continuous loads; when installing breakers, we usually presume we have continuous loads. For non-continuous loads (less than 3 hours of continuous use) like power tools, you can put 20 amps on a 20 amp circuit.
Here is how we calculate how many amps we can actually put on a 20 amp circuit, accounting for NEC 80% rule:
Allowable Amps On 20 Amp Circuit = 20 Amps × 0.8 = 16 Amps
As you can see, we can put at most 16 amps on a 20 amp circuit. This answers the second question:
Can You Put A 15 Amp Outlet On A 20 Amp Circuit?
Yes. You can very well put a 15 amp receptible on a 20 amp circuit. In fact, with the highest allowable amps on a 20 amp circuit in mind, you can put a 16 amp outlet on a 20 amp circuit.
Obviously, you cannot put a 17 amp, 18 amp, 19 amp, or 20 amp output on such a circuit.
This NEC 80% rule is there for safety. It prevents you from overloading a 20 amp circuit. In theory, you could put an 18 amp outlet on a 20 amp circuit but you will increase the chances of a 20 amp circuit going up in flames; that’s why you don’t do it despite a 20 amp circuit being capable of handling that amount of electrical current.
Being aware of this NEC 80% rule, you can now calculate how many amps can you put on any circuit. If you need some help figuring out what amps are you allowed to put on what circuit, you can use the comments below and we’ll help you out.