I bought a EVSE with pigtail leads because it had strong conduit around the supply cables to protect them from damage. However now I go to get ready to install the EVSE and I can't seem to find a NEMA 6-50 plug that accepts the below threaded conduit end into the plug's rear end. I understand conduit has many options to terminate it into a box, but surely there is some need to have the cable protected by conduit up to plugs, no?
Best Answer
This is possible, but only if you ditch NEMA 6-50, and you'll need a written Code variance for it due to EVSE-specific requirements
The use of a plug on the end of a flexible conduit whip is not unprecedented; some industrial and hazardous location applications require the extra protection conduit provides, or unusual conductor configurations that don't correspond to stock cordage, and thus use plugs attached to the end of flexible conduit whips or pendants instead. However, you can't do this with any old garden-variety plug; a special adapter is necessary, and that adapter won't fit on standard plugs as it replaces the plug's cord grip, which is an integral part of the housing on standard plugs.
Furthermore, while locking 50A plugs are available with adapters to convert them to conduit whip usage, NEC 625.44 prohibits the use of locking plugs for connecting EVSE to building electrical systems, presumably due to issues with forces on the EVSE during a forcible decoupling incident (IOW: someone trying to drive off with the car still plugged into the charger). This would normally force us to go with pin and sleeve type plugs and receptacles; these are standard worldwide and in US industrial work for high power applications, and have flexible conduit adapters available as a result, but are not used domestically at all in North America. However, there aren't any 50A pin-and-sleeve configurations, either; your choices are either the 30/32A configuration, or the 60/63A configuration, and the latter's no good as 625.44 also limits the plug size of a non-hard-wired stationary EVSE to 50A.
So, I'd explain your concerns to the local electrical inspector, and see if they'll grant you a variance to use either a 50A locking plug or a 60/63A pin-and-sleeve plug on your EVSE, provided you use the correct conduit adapter for the plug you are using. Note that either way, you'll be quite limited as to where you can plug this in compared to standard NEMA 6-50 or 14-50 plugs, but those, as I said earlier, won't fit on flexible conduit at all, and it's quite unwise to try, either, as the strain relief just won't work out the way you want it to.