Originally Posted by KE2KB
That splice thing looks like it could be used for zip cord, not NM cable.
I think code still says all splices need to be inside a J-box. Even if those little splice gizmos were allowed, I wouldn't use them.
Someone who knows the code better than I do will answer this for you.
These are legal, but not very sturdy, in my opinion. I have done alot of service in mobile homes, and the main failure points I have encountered were/are these types of connectors that join the parts together, and the enclosed feed-thru switch and receptacle design.
Ideally, the OP would change the cable. Probably not likely. The best splicing solution, at least in my opinion, is two junction boxes. But in all reality, if that black wire is not nicked to the copper, and the conductors are not otherwise damaged, a couple wraps of tape would probably be best. White tap if you like. Like I just read, K.I.S.S.