When counting receptacles or outlets for a branch circuit (where the limit is typically 10 or 12 outlets), does a typical duplex receptacle count as one or two? It seems that they each count as two, but I'm having trouble finding something that clarifies that (one post I saw said two on the same yoke count as one).

I'm wiring up an electronics lab space and I need lots of outlets. This is usually solved with long power strips containing 10 or more outlets. I wanted to put in three 2-gang boxes with duplex receptacles in each spot. That's 12 or 24 outlets, depending on the interpretation.

So, is this one or two receptacles/outlets?

enter image description here


  • There is no NEC limit on number of receptacles - some LAHJ may have such cockamaimie rules. Calculated load on the circuit rules - in a typical "electronics lab" you'd be hard pressed to overload a 20A circuit with 20 outlets on it, unless you really love vacuum tube equipment. OTOH, why not toss a couple of circuits at it and put white outlets on one and brown or black on the other so you can manually load-spread?
    – Ecnerwal
    Feb 13, 2018 at 2:28
  • See: diy.stackexchange.com/a/63330/18078
    – Ecnerwal
    Feb 13, 2018 at 3:11
  • I get that there's no NEC limit, but there is the industrial/commercial limit, and I actually lied; this is in a commercial setting (I was using that guideline anyway). But that answer doesn't answer my question. My question is, is a duplex receptacle one or two outlets? See the image I added to the question. Thanks!
    – Rick
    Feb 13, 2018 at 8:30
  • Oh, and the reason I can't add another circuit is because I've hit the limit for box fill through the conduit path that feeds this office.
    – Rick
    Feb 13, 2018 at 8:33

3 Answers 3


First of all let me point out that there is an NEC limit to the amount of receptacles you can put on a circuit (see Exhibit 220.4). Second I have attached the page in 220.14 in the NEC hand book that answers your question on how your receptacles are counted on a circuit(Exhibit 220.3). Feel free to read the entire page. enter image description here

I would suggest that since you are indicating you are installing quad's for a tech bench you actually use the calculation for "Fixed Mutlioutlet Assembly" NEC article 220.14 (H). I have attached that page also (see Exhibit 220.2). enter image description here

Keep in mind that the NEC is a minimum requirement and should be considered as such.

Good Luck

  • I think your post beat mine by 45 seconds.
    – Swanson
    Feb 13, 2018 at 13:36
  • But this one fails to note that the limit in question only applies to commercial, not residential.
    – Ecnerwal
    Feb 13, 2018 at 20:30
  • Thank you for this very thorough answer. I just bought the NEC Handbook ($191!) because of it. Thanks!
    – Rick
    Feb 14, 2018 at 2:59
  • One point of clarification: I only have duplex receptacles available to me, and it's simplest to wire them in 2-, 3- or 4-gang boxes. (H) shows long strips with wide spacing between outlets. How do duplex receptacles figure into H? Is a "fixed multioutlet assembly" a product I need to buy specifically?
    – Rick
    Feb 14, 2018 at 4:12
  • @Rick - Let's start with your question. First you are saying your are wiring up an electronics lab. That's telling me this is a commercial application. Even if this is in a residence a commercial application applies. Also you are saying you are doing this "instead" of using a power strip, so you are actually using the quad's you are installing in lue of a power srtip. So any good designer would use the 180VA per foot calculation to make sure you have adequate power for your work area. Hope this helps. Feb 14, 2018 at 13:38

There is a limit on the number of plugs for non-residential projects.
enter image description here NEC 220.14(I) Each yoke is counted at 180 VA. If there is one outlet, two outlets (most common) or 3 outlets it is still counted as 180 VA. If there are (4) or more outlets then it is counted as 90 VA per outlet.

What you are describing, a double gang box, with (2) duplex outlets will equal 360 VA. Having a total of (3) pairs of duplex outlets will be 360 * 3 = 1080 VA. Since each duplex is 180 VA it can also be counted as 180 * 6 = 1080 VA.

The long power strips that you are used to with 10 or 12 outlets is commonly called plugmold. In the NEC it is referred to as a fixed multioutlet assembly. Per NEC 220.14(H) the load depends on if the plugs get used simultaneously or not. Simultaneous use equals 180 VA per foot of length. Non-simultaneous use equals 180 VA per 5 foot length.


Its two receptacles

A duplex receptacle is two receptacles, sharing the same device yoke -- you can also get a single receptacle on a yoke, which looks like this (product in image for illustration purposes only):

single NEMA 5-15 receptacle

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