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I am adding some additional outlets and outside lights to my garage. The existing outlets are on 12 gauge wiring, so presumably a 20 amp circuit (I did not check this - did not have my reading glasses with me when I was at the breaker box 8-). The lighting fixtures are LED type, so very low power needs compared to incandescent lighting. I was considering running 12 gauge to the new outlets, and 14 gauge from the new outlets to the outside lights (the lights are the terminal equipment in all cases), but I believe I would need 15 amp protection for that portion of the circuit. After a large number of not-very-useful searches, I finally came across this stackexchange question, which nixed my idea of using a 15 amp GFCI. I could not find so straightforward an answer for AFCI outlets, but I assume the same is true.

So, my question is, is there an outlet-mounted device (preferably with actual outlets) that can provide 15 amp overcurrent protection to the next device in the branch?

As an aside, is there, by any chance, a provision in the U.S NEC for connecting a low demand device at the end of a circuit this way without addition overcurrent protection? (I expect not...)

* Edit *

Some additional searching has lead me to panel mount thermal circuit breakers, such as these devices:

Carling Switch Circuit Breakers

Schurter TS-709-15 Circuit Breaker

leading me to wonder if I could put one of these in an electrical box where the 12 gauge and 14 gauge meet, and be to code.

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  • My understanding is a breaker that includes GFCI and/or AFCI, by definition includes overcurrent protection (because that is what a breaker does), a GFCI or AFCI device (e.g., with outlets) downstream from the panel does NOT provide overcurrent protection. And, except for a wire-change situation as you described, most people would never need such a thing. That being said, I have (came with the house, at least 40 years old) a basement workshop set of breakers designed as "ordinary looking" switches in a regular 1-gang box. No idea if such things are made any more. Sep 4, 2018 at 16:59
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    The Carling and Schurter items you linked appear to be designed to be built as part of equipment, not to be inserted as a part of the normal building electrical system. While they would technically work to get the job done, I have a feeling they won't pass inspection. Plus the work involved would be significant - they don't have normal screw terminals like a regular switch. A quick look at homedepot.com ~ $25 extra for 250' 12/2 vs. 14/2 - 10 cents a foot! Unless you are dealing with really long distances, just get the 12/2 and be done with it. Sep 5, 2018 at 0:40

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Your assumption is correct. The over current device is there to protect the entire wiring system from a fault and this does not change even if you install a low voltage device at the end of the circuit.

You can only install an overcurrent device in an approved designed enclosure and this is regulated by NEMA in order to meet NEC requirements.

There are methods of installing overcurrent protection so you can reduce the size of the wiring to a device, but I don't want to release that information to any DIY since there is a better than average chance it would be installed incorrectly or abused. I believe something like that needs to be done by a licensed professional with the correct parts that can not be purchased from a standard big box or local hardware store.

So weighing price between installing a #12 or an overcurrent protection, I would think the #12 would win out.

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I know this question is almost 4 years old at the time of me writing this reply, but I'm sure other people have run into this issue. While my situation is a little different, as I'm trying to add overload protection to a cart which uses a power inlet box that you would normally use to hook up a portable generator to a generator transfer switch, it comes down to the same problem of adding an inline breaker.

As pointed out by Retired Master Electrician, over current protection devices can only be installed in an approved enclosure so even though my application isn't likely to be inspected, I can't buy a gang-box mounted breaker because no one seems to make one. While I could buy a panel mount thermal over current breaker an mount it to a blank decora insert, it wouldn't be high current enough for my application.

The correct solution

This is why these load centers with only two breakers exist:
https://www.lowes.com/pd/Square-D-30-Amp-2-Spaces-2-Circuit-Main-Lug-Load-Center/3457972
Small load center with two breaker knockouts

One of these can be installed inline between your outlets and the main breaker. The outlets can be moved to a new breaker in this tiny load center, and the new lighting circuit can be added to a second breaker, converting the original circuit into a sub panel circuit.

According to Can a circuit connecting to an outlet be branched as a subpanel? you cannot have any outlets upstream of the new sub panel, as a circuit must either be a feeder or a branch circuit, not both, so you must make sure there is nothing else on the circuit upstream of where you are branching off your new lighting circuit.

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  • Welcome to the site - that's a well formed answer, keep up the good work !
    – Criggie
    Feb 3 at 0:32

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