When I was reworking the boxes in this house after moving in I found quite a few splices that were just twisted and taped. It was an interesting method too. He twisted about an inch of wire, leaving about 3/4" of twist, very tight then there was a 3/4" pigtail of one conductor sticking out that he folded over the twist and crimped down with his pliers.
They were all very neat and done exactly the same way so I assume he learned that somewhere but I have never seen it anywhere else. There was no indication that these joints heated up, even the ones going to the 1440w heaters in the bathrooms. Both bathrooms were remodeled and all of that wiring was replaced. It was easy to spot. The original house wiring was silver paper NM, this was brown plastic NM with the color coded copper (neutrals were tinned). I think it is all gone now.
