Some history:
1. Cam-Lok E1016 connectors were first used in an entertainment application on Colortran 6 x 6kW portable dimmer packs, circa 1977. In order to attempt UL Listing, they needed non-intermateablility of hot, neutral and ground. This was at least 7 years prior to NEC recognition of single conductor feeders and single-pole separable connectors, with their associated connection-order rules. Without these NEC rules, UL made up some of their own: no intermateability of hot, neutral, ground. (Note that even today, the NEC makes no statement about non-intermateability of these specialized connectors).
2. Colortran used Empire Products E1016 males on the hots, an E1016 female on the neutral, and a female Palmgren Screw-Lok on the ground. The Palmgren Screw-Lok was a hideously expensive, long lead-time connector that used the same female neoprene housing as an E1016, but was not mateable with E1016. Another great feature: its cable boots only came in a vulcanized version, not the "Lektra-Link" style that is now standard on E1016. That meant:
--A vulcanizing press
--Vulcanizing tape
--Gooey vulcanizing lube
--At least 10 minutes curing time per connector
--No field installation or removal, unless you had a vulcanizing press in your workbox
Palmgren Screw-Lok connnectors
www.integro-usa.com
3. Production Arts owned a bunch of those Colortran packs, and after extreme frustration with the Palmgren Screw-Lok's, we changed them out for female E1016's. Our logic: better to guarantee no intermate of hots with neutral and ground. That arrangement became our standard on touring gear, and I guess our logic caught on with some other rental companies-- but there were notable holdouts such as Vanco.
ST