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?
Edit: Just for completeness, 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.