Question about wiring for 240V well pump
My 1HP 240V deep well pump runs on a 12-2 w/gd NM cable which goes from the box in the basement out through a hole in the concrete wall and then underground to the well house. There is a joist-mounted junction box on that cable in the basement which I opened earlier today to see what it was there for. Apparently it was put in just to splice two pieces of cable together because there is white cable going in from the breaker box and yellow cable going on out to the pump. What I don't understand is that the black and white insulated wires in the cable are connected with wire nuts as they should be, but both ends of the bare ground wire are also connected together with wire nuts and wrapped with black tape from the cable sheathing to and over the wire nut so that no part of it is exposed. And of course the bare wire isn't screwed to the metal box like I would expect it to be if it was serving as a ground wire. All that leads me to think it must be carrying current or acting as a common on that 240V circuit because if it was serving as a normal ground wire it wouldn't need to be insulated and wire nutted together. It must work OK since the pump works fine, and I assume that it was wired by a licensed electrician when the house was built 10 years ago. But I would still like to know just how that hook-up works and if it's legal. I always thought that 240V cables used 2 hot wires with one common wire and a ground wire, but this hook-up doesn't seem to use the bare wire for a grounding wire. I have learned quite a bit by reading this forum, but as you can see there's a lot about the wiring for 240V appliances that I still don't understand.