Hopefully my troubleshooting can help people having difficulty charging with standard 110V outlet.
I am waiting for my 240V NEMA, just tried charging my new Model X with 110V, but sadly the adapter and charging port both blinked with red light and the car reporting cable fault.
So I decided to troubleshoot a little bit.
The first thing I did was test which hole was neutral and which is hot, and surprisingly they are reversed! Apparently the previous home owner or electrician didn't know what they were doing.
I had to switch the wires to make them correct (the longer vertical hole should be neutral, the shorter one should be hot, and the round hole should be ground), during the project, I also noticed the outlet was not properly grounded at all.
Plugged back, still not working ... The damn red flash ...
I then measured the voltage between real ground (wet soil outside) and the shell of outlet which is connected to the ground hole, surprisingly, it read around 100V! There must be some current leaked from hot wire to the shell.
But after unplugging the adapter, the reading went to zero, so apparently it was the adapter itself trying to test if ground is connected by inducting some small current from hot wire.
Now I simply connect the shell with ground, and finally the pleasant green led is flashing. The ground is not perfect, and I think the impedance must be pretty high, but should be good enough to let the adapter pass the test.
Now it charges with 117V/12A, 1.4 kW, though slow like a turtle, it should cover my commute!
I now even think the 240V NEMA is not necessary, since I have good access to quite a few super chargers when doing long distance trips, and charging stations at work.