I have two 60A (to my knowledge) split-phase outlets (14-50R) in a commercial building, which I'd like to break out semi-permanently to 120V outlets, ideally without having an electrician modify the building.
I took an educated chance and wired up two branches of 120v (hot-neutral + ground) from one of these receptacles to power an LED screen array. The wiring was done inside the plug, so there are two three-wire cables coming out, terminated by "Powercon" connectors (but they could just as easily be 5-15 style). Each branch has an equal number of panels, and so the branches are about as close to balanced as possible (although there is always the possibility of some panels drawing more than others).
This has been working well, but a bit of self-doubt has set in; most importantly, is this safe? Would it be smarter to build a small sub panel which is fed through the 14-50 plug? If it is acceptable, can I safely do it again with the other circuit, without the guarantee of a mostly balanced load?
Best Answer
You should make a plug-in subpanel. Remember to keep ground and neutral isolated in the subpanel.
You don't need to worry about balancing loads - if the loads are balanced, the current in the neutral is zero, otherwise it's more than zero, in any case it's fine if the circuit is properly wired. This is the way it works into your house/building and at every sub-panel feed.
You want a sub-panel so that there are more-reasonable sized (15-20 amp) breakers on your 120V circuits, rather than a 60 amp - unless your 120V circuit is a 60 amp circuit with all conductors properly sized for that load.