Keep in mind that this may not be about what voltage is coming from the power company but what voltage is available in the RV park due to various factors I tried to explain in previous posts in this thread.
Also, today's electronics require correct polarity and could get fried if polarity is not correct - pounding a ground rod into the ground is a great idea and certainly worth doing - it could save a life - but it will not provide correct polarity to sensitive devices.
We also once experienced a regular 15amp 120vac outlet that was wired so 240vac was seen by our meter.
There is no one solution to being aware of and testing for electricity no matter where we travel. Again - this is not just about Mexico.
