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I have a 20 amp circuit in my home (the breaker is 20 amps). On that circuit there is a light switch rated for 15 amps that controls three 15 amp receptacles.

Is the 15 amp switch ok, or should it be a 20 amp light switch?

  • 1
    .. and I should clarify that my house "came this way" I just happened to notice it... :) – Greg Dietsche Dec 6 '17 at 22:42
  • I'm thinking there is (or used to be) a specific exception in the NEC allowing 15A outlets on a 20A circuit, under certain limited circumstances. (I think this might be because NEC-approved "15A" outlets are built to conduct up to 20A -- they just don't accept a 20A plug.) I don't recall if the exception would have allowed a 15A switch as well. – Hot Licks Dec 7 '17 at 4:26
  • @Hot Licks Yes, according to Article 210.21 a 15 amp receptacle can be on a 20 amp circuit. However, if you are going to switch that circuit, the switch has to be rated for the circuit (20 amps) not the receptacle (15 amps). – ArchonOSX Dec 7 '17 at 10:39
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Dean MacGregor is correct.

Here is the pertinent National Electrical Code Article.

Article 404.14(F) Cord- and Plug-Connected Loads. Where a snap switch or control device is used to control cord- and plug-connected equipment on a general-purpose branch circuit, each snap switch or control device controlling receptacle outlets or cord connectors that are supplied by permanently connected cord pendants shall be rated at not less than the rating of the maximum permitted ampere rating or setting of the overcurrent device protecting the receptacles or cord connectors, as provided in 210.21(B).

So, basically the switch needs to be a 20 amp switch for multiple receptacles on a 20 amp circuit.

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In theory it's fine as long as the combined draw of the 3 receptacles never goes above 15amps. Of course since you won't really know whether or not that is the case, what happens if you accidently do draw more than the 15 amps on those 3 outlets? Well, the breaker won't trip (unless you go over 20 as well) because it's a 20amp breaker so the switch will be overloaded and could heat up and start a fire.

TLDR: no not ok.

  • Agreed, this is just asking for some numbnutz to put a gaming PC, laser printer, air conditioner (to remove all the heat) and a piece of tape on the switch. One 15A receptacle would be a different matter. – Harper Dec 6 '17 at 20:28
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    @Harper apparently the answer is exactly one according to my reading of this diy.stackexchange.com/questions/12115/… – Dean MacGregor Dec 6 '17 at 20:39
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    @Harper: The rules about receptacles are a bit weird and are likely a result of practices that existed before they were written. In most cases, everything served by a certain capacity of breaker should be capable of withstanding that quantity of current without overheating, regardless of the expected load, but it's acceptable to have a pair of 15A receptacles guarded by a 20A breaker. I don't think such allowance would extend to using a 15A switch on a 20A-fused circuit, however, even if it was only serving a single 15A receptacle. – supercat Dec 6 '17 at 23:52
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    @supercat - You can't plug a 20A plug into a 15A receptacle. – Hot Licks Dec 7 '17 at 3:24
  • @HotLicks: If devices plugged into receptacles could be relied upon never to more current than they were supposed to, there wouldn't be a need for any circuit breaker on a receptacle fed by a home-run circuit to the panel. Especially the wide availability of unfused multi-tap adapters, the fact that a receptacle has a 15A shape should not be taken to imply that nothing will ever draw more than 15 amps through it. – supercat Dec 7 '17 at 15:25
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Short answer: No, it is not good at all. Any protection shall break first with large enough margin, no matter what and how it protects. Fuse, breaker, torque limitter,...

Fuses and breakers shall be the weakest points in the circuit, because they are designed to "fail" safely. 15A switch will burn without 20A fuse ever noticing it. They must break first to protect the rest. If they don't, they are no more a protection.

If you want to use 15A switch you have to protect it with at most 15A rated fuse/breaker. In other words, you have to create sub-circuit with lower rating and appropriate protection.

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