So I was working on breaking a tandem 15A single-pole breaker into two 15A single pole breakers, one being a Combination AFCI. After getting the panel open and moving one circuit to a new, 15A single pole (non-CAFCI), I discovered that my second circuit, the one I want on the CAFCI, has too short of a neutral wire to reach the CAFCI breaker's neutral screw. It looks to have been shortened to be just long enough to reach the neutral bus bar.

Is it against code to splice/pigtail a new, short piece of romex onto the existing neutral (w/ a wire cap) so I can connect it to the CAFCI's neutral screw?

This relates to this question. I was replacing the AFCI receptacle with a CAFCI breaker, on the advice of an electrician, when I encountered this short neutral wire inside the panel. The electronics and sensing apparatus inside of an actual CAFCI breaker have been around long enough that most of the kinks have been worked out. The Leviton AFCI Receptacle, OTOH, is still fairly new and might not be usable in all wiring configurations yet.

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    It's fine and common practice. Mar 9, 2014 at 11:39
  • Others have said it is fine, I will just add that just because you can, does not mean you should: try to avoid it unless it is necessary, otherwise you risk having a bunch of extra crap in the box making things more difficult to understand. For example, I had to rework some of the garage circuit, so I move those splices to a separate junction box a foot away and ran fresh Romex between the two. Throw up a sticker with the circuit number on the box and wammo, all three garage splices are in the same box, and the load center is still nice and neat and organized.
    – user4302
    Mar 11, 2014 at 3:38
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    @John: As mentioned in my question, the neutral wire coming out of the romex for the circuit in question is literally too short. There really is no other way, short of opening the wall up and replacing that romex run, to avoid this. And to add, the breaker panel is recessed on a wall in my living room, not down in a basement (because I don't have a basement). Small house :)
    – Kumba
    Mar 12, 2014 at 9:43
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    @Kumba I know, that is why I said "try to avoid it unless it is necessary" and it is necessary in this situation. Please keep in mind that people find these SE questions years later via Google looking for similar issues.
    – user4302
    Mar 12, 2014 at 16:29

2 Answers 2


National Electrical Code 2011

Chapter 3 Wiring Methods and Materials

Article 312 Cabinets, Cutout Boxes, and Meter Socket Enclosures

I. Installation

312.8 Switch and Overcurrent Device Enclosures with Splices, Taps, and Feed- Through Conductors. The wiring space of enclosures for switches or overcurrent devices shall be permitted for conductors feeding through, spliced, or tapping off to other enclosures, switches, or overcurrent devices where all of the following conditions are met:

(1) The total of all conductors installed at any cross section of the wiring space does not exceed 40 percent of the cross-sectional area of that space.

(2) The total area of all conductors, splices, and taps installed at any cross section of the wiring space does not exceed 75 percent of the cross-sectional area of that space.

(3) A warning label is applied to the enclosure that identifies the closest disconnecting means for any feed-through conductors.

This is the applicable code section. It used to say no splices were allowed unless there is enough room. This led many, many folks to simply state "NO splices allowed". They were wrong. You'd be amazed at what it would physically take to reach that 75% number of fill.

So basically yes, splices are FINE in a breaker panel.

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    And, in fact, they aren't uncommon during box replacement, when getting a clean layout may require a few splices. Mar 10, 2014 at 1:10
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    Splices in the panel are also common when installing transfer switches for generators.
    – Tester101
    Mar 10, 2014 at 10:41
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    @speedyPetey When quoting NEC (or any code) please include the code version (year), since code numbers and verbiage change from time to time.
    – Tester101
    Mar 10, 2014 at 10:47
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    There is no problem quoting sections of NEC. @SpeedyPetey I edit to include relevant section titles, to make it easier for folks to find this information in the original texts. Code sections do move around from time to time, and it makes it easier to locate the information in the future if you have a bit of extra information.
    – Tester101
    Mar 11, 2014 at 10:03
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    @Speedy Petey: Funny thing is, I actually have a copy of the 2011 NEC code book. I just wouldn't have known where, in its ~850 pages, to start looking. Likely because I don't call my panel a "cabinet" or "enclosure for overcurrent devices" or other such term, but either an "electrical panel" or "breaker box".
    – Kumba
    Mar 12, 2014 at 9:40

It's fine. Someone else may be able to provide a code reference, but in general your breaker box is a junction box, it's sealed, and splices are normal.

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    Bryce: I wish I could assign points for "assisted answer" or such, but I gave it to Speedy for citing the relevant code bits. Thanks!
    – Kumba
    Mar 9, 2014 at 21:26

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