Re: Not mains but wiring just the same
Do an image search for "IBM Token Ring Hermaphroditic connector". That's the Type 1 Token Ring connector. It's hermaphroditic in that unlike most other connectors there's no male and female version. It's just the same connector. It's a clever idea but the execution left a lot to be desired. The connectors were huge (you could only fit 10 across a standard 19" rack), had an annoying tendency to fall apart and also used ridiculously thick cables.
As the Type 1 connectors were far too big to fit on a PC expansion card there was a 9-pin D-type connector at that end that also happened to be identical to the 9-pin D-type connectors used for MDA/CGA/EGA video connections. Cue lots of users plugging their network cable into their video card and vice-versa.
Type 3 connectors were standard RJ45 on Cat3 cabling and so were much easier to live with.