I have an EV charger that uses a NEMA 14-50 outlet with 6 AWG back to a 50 amp breaker. The outlet is in a location where there are no nearby 120 V outlets and it would be convenient to occasionally to have 120 V there instead.
Functionally it is possible with just a dryer plug, a 20 amp duplex outlet, and a box to create an adapter to convert (in the functional sense, not physics) the 240 V outlet into 120 V.
Edit for clarification: I'm not talking about making a permanent hard wired change to my home's wiring. I'm talking about a stand alone adapter that I can unplug the EVSE and then plug in this adapter on an as needed basis and then switch it back. In this way it's impossible for both to be used simultaneously.
One safety failure of the adapter is if a device pulls more current than its own cord (or internals) can handle but less than 50 amps because it wouldn't trip the breaker and potentially cause a fire. Is there anything else I'm missing? I saw some inline circuit breakers on Amazon for up to 250 VAC 20 amp. Would that be a way to fix the safety issue or am I thinking about it too simplistically? What is wrong with adding these sort of circuit breakers to the outlet?
Another clarification: I'm not interested in adding a subpanel for a few reasons.
- It requires a permit
- It is more expensive even setting aside the permitting cost
- It's cumbersome on the wall
- It would then allow the car to charge while also using the 120 V at the same time. In doing so, it may trip the 50A breaker since the car pulls quite a bit of current unless. I recognize that I could reduce the charging rate but I don't want to.