At a campground the 14-50 box is right next to the meter and the breaker switch. Proper procedure is to be sure breaker is OFF, then hook up your charge cable, then finally flip breaker to ON. You could also wear a rubber high voltage glove on the one hand. And high voltage rubber boots like Tesla techs wear while digging into your MS. Your call.
I can't remember if the breaker was part of the meter box and the 14-50 was separate, or if they were all part of the same unit. It was specially made for campgrounds, nice & compact.
My 14-50 box (made by Eaton, bought at HD - same as link below) has room for a good sized breaker or switch to be installed in the box, but there is no knock-out for such. If the distribution panel is far away from the 14-50 location then it would be convenient to mount a DPST 50 Amp switch in the box (50 Amp minimum). If it won't fit then in its own box.
From 14-50 box: "Turn disconnecting means or circuit breaker OFF before inserting or removing plug. Plug must be fully inserted or removed." So this seems to ok use of switch in series with the remote breaker. Flasher, please chime in!
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