Breaker ratings aside, I would like to know how he terminated the original 50A wiring to a 15 A receptacle.... [Linked Image]

Here is another , even more worrisome attempt at a similar retrofit, from a recent Usenet post:

Quote
I have a 220 knob and tube outlet behind my range I need to convert to
110. The wires are in good condition, there are 6 individual wires on
the hot, 7 on the neutral and 6 on the ground. I spoke to a contractor
and he recommended that I just wirenut off one each of the hots and
neutrals, and connect the rest to a normal plug.

My question is, since there are 6 and 7 wires on the hot and neutral,
respectively, will it work to just wire nut and tape off 3 and 4,
respectively, or does this present problems. If the method above is
completely off-base and unsafe that information would also be helpful.