To determine how many outlets you can have on a 30-amp circuit, apply a general rule or work it out exactly according to the appliances you will use.
Each outlet normally has two receptacles on it. You can install up to 10 such outlets on the same circuit (ideally, no more than 8), but it depends on the total power you need for your appliances. It must not exceed 2,880 watts (on a 120V supply). So, irrespective of how many you install, you should not use more than this simultaneously.
General Rule
A general rule of thumb to estimate how many outlets you can have on a 30-amp circuit is giving no less than 1.8-2 amps per receptacle (or maximum 1.5 amps).
We divide the maximum current allowed (30 amps) by the current we will allow per receptacle:
Number of outlets = 30 / 1.8 = 16.67, or 30 / 2 = 15, so 15 or 16 receptacles
Absolute maximum = 30 / 1.5 = 20, so 20 receptacles
So this means between 7 and 10 outlets (maximum) if you have 2 receptacles on each outlet.
The general recommendation considers that you should use no more than the 80% current threshold, and you should not exceed the maximum.
Exact Number of Outlets
Suppose you would like to know exactly how many outlets you can install (or, rather, use concurrently) on the same 30-amp circuit. In that case, it depends on the power consumption of your appliances and how many receptacles are on each outlet.
As per the above calculation, if you choose to have, say 20 receptacles (viaten0 double-receptacle outlets), then the maximum current you will allow per receptacle is 1.5 amps, assuming it is equal across all the outlets.
However, you can have up to 30 amps in total (theoretically), irrespective of how you divide the current between the receptacles. But for regular use, you should not use more than 80% of this limit. This means the current should not persistently exceed 80% of 30 amps, which is 24 amps.
If your electricity supply is 120V, this means the maximum power you should allow is:
Given by P = IV = 24 x 120 = 2,880 watts
So if you want to use a heavy appliance that requires this much power, it should be a single, dedicated receptacle. You shouldn’t share it with any other receptacle or outlet.
You can have more outlets on the same circuit (up to 9 more double-receptacle ones), but the total concurrent power draw across all of them should not exceed this wattage. That is, they should not be operational at the same time.
Now that this point has been made clear, here are some possibilities (assuming that each outlet is used for the same power draw simultaneously):
- 1 outlet for a single heavy appliance that requires up to 2,880 watts, either with a single receptacle or an unused second one.
- 2 outlets where each is used for no more than 1,440 ( 2880 / 2) watts together.
- 3 outlets where each is used for no more than 960 ( 2880 / 3) watts together.
- 4 outlets where each is used for no more than 720 ( 2880 / 4) watts together.
- 5 outlets where each is used for no more than 576 ( 2880 / 5) watts together.
- 6 outlets where each is used for no more than 480 ( 2880 / 6) watts together.
- 7 outlets where each is used for no more than 411 ( 2880 / 7) watts together.
- 8 outlets where each is used for no more than 360 ( 2880 / 8) watts together. (Recommended maximum)
- 9 outlets where each is used for no more than 320 ( 2880 / 9) watts together.
- 10 outlets where each is used for no more than 288 ( 2880 / 10) watts together. (Absolute maximum)
FAQs
What types of appliances require a 30-amp circuit?
A 30-amp circuit is typically required for high power-demanding appliances, such as air conditioners and clothes dryers.
What wire will I need for a 30-amp circuit?
A 30-amp circuit typically requires a 10/2 wire. You cannot use thinner 12/2 or 14/2 wire on it. You can use thicker 8/2 if you want, but it is usually unnecessary and will cost more. It may only be recommended if you have a very long run or constant heavy appliance usage.