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How many outlets can be on a 20 amp circuit in a garage?

How many receptacles can you put on a 20 amp circuit? Theoretically, there is no upper limit on how many outlets you can put on a 20-amp circuit. For example, you can put on 1 space heater, 2 fans, 3 lights, and so on.

learnmetrics.com - How Many Outlets On A 20-Amp Circuit? (+ How Many Watts)

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The 20-amp circuit is the most common circuit in the US. Since a lot of our visitors have asked ‘how many outlets can you put on a 20-amp circuit’, we decided to give you some insight on this topic. We will not only look at the number of plugs on a 20-amp breaker but, more importantly, the total net amperage and wattage you can put on a 20-amp circuit as well.

How many receptacles can you put on a 20 amp circuit?

Theoretically, there is no upper limit on how many outlets you can put on a 20-amp circuit. For example, you can put on 1 space heater, 2 fans, 3 lights, and so on. Practically, however, the number of outlets you can run on a 20-amp circuit is limited by only one thing:

Amp draw.

A common misconception is that you can connect up to 20-amps worth of electrical appliances on a 20-amp circuit. This sounds pretty self-evident but, practically, if you put a 20-amp current on such a circuit, you will very likely fry the 20-amp circuit.

How many outlets on a 20 amp circuit by NEC code?

Realistically, regardless of the number of outlets, you’re recommended to not put more than 16-amps worth of electrical appliances on a 20-amp circuit. This is the maximum load specific by NEC Article 210.21 (B) which states that you can put a maximum load of 16 amperes on a 20-ampere circuit. Let’s look where the ’16 amps’ comes from. We’ll also look into how many watts can a 20-amp breaker handle safely:

Number Receptacles On A 20-Amp Circuit Shouldn’t Surpass 16-Amps

National Electric Code (NEC) doesn’t have a directive for the maximum number of outlets you can put on a 20-amp circuit. You can put on any number – from 1 to infinity – as long as you keep the total amp draw below 16 amps.

Why 16 amps exactly?

The NEC directive on the question of ‘how many outlets on a 20-amp circuit’ states that you shouldn’t put on receptacles with a net amp draw that surpasses 80% of the circuit breaker limit. In the case of a 20-amp breaker that’s 16-amps. Here’s how you can easily calculate that. 80% of a 20-amp breaker is:

20 Amps * 0.8 = 16 Amps

Example: How many watts on a 20 amp 240V circuit? In theory, a 20 amp 240V circuit can produce 4,800 watts. In practice, you have to account for the 80% NEC rule; a 20 amp 240V circuit can produce 3,840 watts (because you can allow for 16 amp current only). Now, we can see how many outlets can fit on a 20-amp circuit, if we know their current draw (amp draw).

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Note: We usually know the wattage of the outlets. Example: 1,500 W space heater or a 100 W light bulb. We’ll look at how we can use the voltage our circuit is on (120-volt or 220-volt) to calculate amps from watts; ie. 100 W light bulb on the 120-volt circuit has 0.83A amp draw. Before we answer how many watts can a 20-amp breaker handle, let’s see a theoretical table of how many outlets on a 20-amp circuit won’t trip the 20-amp breaker: Outlet Amp Draw: Max. Number Of Outlets (On 20-Amp Circuit): 1 amp 16 outlets 2 amps 8 outlets 3 amps 5 outlets 4 amps 4 outlets 5 amps 3 outlets 6 amps 2 outlets 7 amps 2 outlets 8 amps 2 outlets 9 amps 1 outlet 10 amps 1 outlet 11 amps 1 outlet 12 amps 1 outlet 13 amps 1 outlet 14 amps 1 outlet 15 amps 1 outlet 16 amps 1 outlet 17 amps 0 outlets 18 amps 0 outlets 19 amps 0 outlets 20 amps 0 outlets From the table above we see that the net product of a number of outlets and amp draw of individual outlets must not be more than 16 amps. Now, practically, it’s much more useful to know how many watts can you put on a 20-amp breaker. Let’s look into that as well:

How Many Watts Can A 20-Amp Breaker Handle?

Amp draw is determined by two factors that are known to us:

Wattage. Example: 100 W light bulb. Voltage. We usually deal with 120-volt and 220-volt circuits. Batteries operate on 12-volt or 24-volt circuits. Here’s how we can calculate the amp draw of an individual receptacle from known wattage and voltage:

Amp Draw (Amps) = Wattage (Watts) / Voltage (Volts)

Let’s solve one example to illustrate how you can use this formula to figure out the amp draw of your outlets. You can also use our watts to amps calculator here for this purpose.

Example: We have a 1,500 W space heater running on a 120-volt circuit. How many amps does it draw?

Amp Draw (120-V circuit) = 1,500W / 120V = 12.5A

Such a space heater draws 12.5 amps. That means that we can put 1 such space heater on a 20-amp circuit. If we would put 2 such heaters on a 20-amp circuit, the total amp draw would be 25 amps; that’s more than the recommended 16 max. amp draw of a 20-amp circuit. Alternatively, if we have a 220-volt circuit, the amp draw will be reduced:

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Amp Draw (220-V circuit) = 1,500W / 220V = 6.82A

That means we can put 2 such space heaters on a 220-V circuit without frying a 20-amp breaker. That’s because 2 heaters would have a net amp draw of 2 x 6.82A = 13.64A. That’s less than 16 amps. What’s more, we cannot put 3 such heaters on a 20-amp circuit because the net amp draw would be 3 x 6.82A = 20.46A; that would be more than allowed 16 amps.

What Is The Maximum Watts You Can Put On A 20-Amp Breaker?

To simplify, we can calculate how many watts can a 20-amp breaker handle, given a 120-volt or a 220-volt circuit. For both voltages, we know that the maximum amp draw is 16 amps. We use the same equation as before:

Amp Draw (Amps) = Wattage (Watts) / Voltage (Volts)

Case of a 120-volt circuit:

Wattage (120-volt circuit) = 16A * 120V = 1,920W

We see that we can put up to 1,920W on a 120-volt 20-amp circuit.

Case of a 220-volt circuit:

Wattage (220-volt circuit) = 16A * 220V = 3,520W

We see that we can put up to 3,520W on a 220-volt 20-amp circuit.

Let’s look at two realistic examples:

#1 Example: How Many Outlets On A 20-Amp Circuit In A Kitchen?

In the kitchen, we usually have a 120-volt circuit.

As we can see above, we can any number of outlets on a 20-amp circuit in a kitchen that have:

Net amp draw equal to or less than 16 amps.

Net wattage equal to or less than 1,920W.

#2 Example: How Many Outlets On A 20-Amp Circuit In A Garage?

In the garage, we usually have a 220-volt circuit.

As we can see above, we can any number of outlets on a 20-amp circuit in a garage that have:

Net amp draw equal to or less than 16 amps.

Net wattage equal to or less than 3,520W.

Hopefully, this answers the questions about the number of outlets you can realistically put on a 20-amp breaker. If you have any questions regarding this, you can pose them in the comments and we’ll try to help you out.

learnmetrics.com - How Many Outlets On A 20-Amp Circuit? (+ How Many Watts)