How Many Outlets On A 15 Amp, 20 Amp, 30 Amp Circuit? (NEC 210.21)

Let’s say you have a 15 amp, 20 amp, or a 30 amp circuit. How many outlets can you put on these circuits? Usually, when we encounter these questions, we consult a relevant NEC article.

The closest guideline to how many outlets can you put on 15A, 20A, or 30A circuits is found in the NEC 210.21 Chapter titled ‘Outlet devices’. This NEC chapter includes a table that specifies circuit ratings, acceptable ratings, and maximum load such a circuit can handle.

This is the ‘210.21(B)(2) Maximum Cord-and-Plug-Connected Load to Receptacle’ NEC table:

You may be wondering: “Well, where does it list the number of outlets I should put on the 15 amp, 20 amp, or 30 amp circuit?”

As you can see, the NEC guidelines do not specify the number of outlets you can put on an outlet directly. This is done indirectly by specifying the maximum load you can put on a 15A, 20A, or 30A circuit.

So, in order to figure out how many outlets can be put on a circuit, we have to:

• Stop thinking about the number of outlets or receptacles.
• Start thinking about how many amps do these outlets or receptacles draw.

Example: A 20 amp circuit has a specified maximum load of 16 amps. That means that you can put on outlets that will power devices with no more than 16 amps; we are talking about a combined amp draw of 16A (for a total wattage of 1,920W for 120-volt outlets). If a receptacle has a 16 amp draw, you can put on 1 receptacle. If it has 18 amps, you can’t put it on; 0 receptacles. If it has a 1 amp draw, you can put on 16 of them.

This is how you can use the instructions listed in the NEC 210.21 table to figure out how many outlets you can put on a circuit. In practice, this ‘you can only put 16 amps on 20 amp circuit’ is known as NEC 80% rule. Namely, this is a security measure; if you would put a 20 amp receptacle on a 20 amp circuit, you would risk the circuit catching on fire.

Understanding this NEC 80% rule, we can quite precisely tell how many outlets to put on 15 amp, 20 amp, and 30 amp circuits if we know the amp draw of the receptacles. Further on, you will find 3 outlet number tables detailing the following:

• How many lights and outlets on a 15 amp circuit? A good rule of thumb is to put a maximum of 8 outlets on a 15 amp circuit. The 15 amp outlet chart below tells you when you should put 1, 2, 4, 6, 8, or 12 outlets on a 15A circuit.
• How many outlets can you put on a 20 amp circuit? A good rule of thumb is to put a maximum of 10 outlets on a 20 amp circuit. The 20 amp outlet chart below tells you when you should put 1, 2, 4, 8, 11, 12, and 16 outlets on a 20A circuit.
• How many outlets can you put on a 30 amp circuit? A good rule of thumb is to put a maximum of 16 outlets on a 30 amp circuit. The 30 amp outlet chart below tells you when you should put 1, 2, 3, 4, 6, 8, 12, 16, and 24 outlets on a 30A circuit.

First, however, let’s look at how to think about connecting this amp draw with the number of outlets:

How Many Amps Per Outlet? This Determines The Number Of Outlets Per Circuit

To answer how many outlets per circuit, we first need to answer how many amps per outlet. We will also explain how many watts per outlet we can get or should aim for.

From the NEC 210.12(B)(2) table we can clearly see that the 15A breaker can handle 12 amps, the 20A breaker can handle 16 amps, and the 30A breaker can handle 24 amps. At 120 volt, this will produce the maximum wattage of 1,440W, 1,920W, and 2,880W, respectively.

Now, the real question is how many amps do different electric devices we will connect to the outlets draw.

Examples for 120V electric circuits:

• A 40W LED light will draw 0.33 amps.
• A big 120W house fan will draw 1 amp.
• A 240W 42-inch plasma TV will draw 2 amps.
• A 360W laptop with extra desktop will draw 3 amps.
• A 1,000W waffle iron will draw 8.33 amps.
• A 1,500W electric space heater will draw 12.5 amps.

This is all good and right, but when we are installing our circuits and outlets, we don’t exactly know what electric devices we will run through our outlets.

With the average amp draw from each outlet unknown, we help ourselves by using this simple rule of thumb:

1.5 amps per outlet.

In short, we presume every outlet will draw about 1.5 amps (that’s 180 watts at 120V). With that in mind, we can easily calculate how many amps we should put on any circuit.

Example: How many amps should you put on a 15 amp circuit?

Here we use two directions, namely:

• NEC table that tells us that we can put at most 12 amps on a 15A circuit.
• Outlet amps rule of thumb that tells us we should calculate 1.5A per outlet.

The calculation of the number of amps on this 15A circuit looks like this:

Number Of Outlets (15A) = Maximum Allowable Amp Draw / 1.5A Per Outlet = 12A / 1.5A Per Outlet = 8 Outlets

We can see that it is recommended to put about 8 outlets on a 15A circuit. That, of course, doesn’t mean we can’t put 1, 2, 4, or even 12 outlets on a 15A circuit. The same is true for 20 amp and 30 amp circuits.

To help you out, you can use these outlet number tables for 15A, 20A, and 30A circuits that will tell you how many outlets you can put on a circuit, given different average electric device amp draws:

How Many Outlets On A 15 Amp Circuit:

A 15 amp circuit has the maximum amp draw of 12A, for a total wattage of 1,440W at 120V. Here is how many outlets you can put on a 15A breaker, given the average amps draw. We have also calculated how many watts can an individual outlet handle if all of them are powering electric devices at the same time:

Practically, we apply the 1.5 amps per outlet rule of thumb. This means that we standardly put 8 receptacles on a 15 amp circuit.

How Many Outlets On A 20 Amp Circuit:

A 20 amp circuit has the maximum amp draw of 16A, for a total wattage of 1,920W at 120V. Here is how many outlets you can put on a 20A breaker, given the average amps draw. We have also calculated how many watts can an individual outlet handle if all of them are powering electric devices at the same time:

Practically, we apply the 1.5 amps per outlet rule of thumb. This means that we standardly put 11 receptacles on a 20 amp circuit.

How Many Outlets On A 30 Amp Circuit:

A 30 amp circuit has the maximum amp draw of 24A, for a total wattage of 2,880W at 120V. Here is how many outlets you can put on a 30A breaker, given the average amps draw. We have also calculated how many watts can an individual outlet handle if all of them are powering electric devices at the same time:

Practically, we apply the 1.5 amps per outlet rule of thumb. This means that we standardly put 16 receptacles on a 30 amp circuit.

With these tables, you can pretty accurately check how many outlets you can put on different home circuits. If you have any questions about this, use the comments below and we’ll try to help you out.