Yes there are codes in Mexico, only when you build and have permits are you going to adhere to codes, after you pass the initial inspection you can do what you want with the electrical wiring even for businesses, after that a 500.oo pesos "mordida" (bribe) to the inspector should he return, you're good to go you pass inspection.
In Mexico if you have electricity, what else do you want?
I have been at some so called RV parks that are nothing more than an empty lot with an enclosed toilet in one corner, a water spigot and a metal conduit with household boxes spaced about 8 feet with regular 2 prong outlets running along the back wall, do you think that they followed the color and wire gage code, NO they did it as cheap as possible, chances are that if you show the guy that did the installation the first schematic on this blog he will not know what it is or understand it.
When travelling to Mexico make sure that you have a good line conditioner for voltage spikes and that your electronics are protected, next time you are here count how many RV parks actually have pedestals as in the states with a meter, on off switches and brakers, all of those fancy schematics and color code wires are useless in Mexico you need to accept the fact that as long as you have current for the light bulb and the TV you are good, chill out and have a cerveza, they are not going to change.
You have to live "la vida loca"
navegator