Taking Socapex for a Spin
Long ago, someone had the brilliant idea to use a 19-pin round connector with 19-conductor cable for distributing power on truss, and the Socapex cable was born. Actually, Socapex is the brand of connector but everyone in the live event production industry calls it Socapex cable, just like all tissues are called Kleenex and all copy machines are called Xerox copiers. (I've heard that it was Eric Pearce, the owner of SGPS/Showrig, who brought the connectors into the live event production industry from the aviation industry in the late 1960s or early '70s, but I've never been able to confirm that.)
Anyway, there is a standard way of connecting the six circuits, as shown in the illustration. That insures that multi-core cables from different production companies will be compatible.
I recently encountered a situation where the circuit numbers were all mixed up. We had just finished labeling all the connectors and we ran the Soco, connected the breakouts and the power cables to the fixtures. But when we turned on the circuits, the wrong lights came on. After some investigation, we figured out that the Socapex connector was spun inside of its outer shell, making the connections with the mating connector different than they should have been. Let's go to the video...