Best would be using
two Wall Charger to be able to
share the load,
Otherwise the NEMA could be disconnected using a
current detector when the Wall charger is used,
in a similar way as the
Dryer Buddy Auto provides this functionality.
Interesting. I have a similar situation as OP. I currently have a dedicated 14-50 and will be adding a second Tesla. I will not be running another line because the cost would be prohibative (would require a panel upgrade, and run in up two stories, across the attic, down two stories that requires zig-zagging 5 walls.).
I looked at using two wall chargers, but there is likely not enough room where the current charger is (it's only about 6.25" width). It _might_ fit, but it would be tight. Also if I had two wall changers and wanted to keep a 14-50 as a backup, the current sensor would need to be placed before both chargers in case either is used, but the 14-50 currently is on the last leg of the run which means I would have to move the 14-50 to the new charging area (i.e. mid run).
So I think the option I am left with is to leave the 14-50/mobile charger where it is now and add another 14-50 at the other wall w/ a current sensor. Then if the new 14-50 is being used it would cut power to the second 14-50.
Picture attached. The wiring currently runs along the right side of the wall (above where the chair is hanging) in the ceiling space, so I would re-open the ceiling there to run new wiring down for the second 14-50 placing in near that chair.
Is using such a device to code? (Texas?) I would likely hire an electrition as I did to install the original.
Also, would having the power shut off/on to that second 14-50/mobile charger be handled well (Model 3). I am assuming if both are plugged in, the new Tesla would charge and as soon as it was done and goes to sleep (i.e. no shore power) the second would charge. Or would having a mobile charger connected to the first while plugged in always be pulling some current that would not allow the second to charge. Wouldn't want to have to unplug every time to charge.
Open to suggestions before calling for install.