# Why is the socket voltage in Mexico 127V?

As per the title, this is a very specific figure. Is there a reason it's 127 instead of 120V or 130V?

• Is there a reason you find the numbers 120 and 130 more natural except that they're easily expressed in "numbers of fingers I have on my hands"? This is not meant to be flippant, but if you ask "why not X", I expect a reason for expecting X. – DonFusili Sep 27 '18 at 14:23
• @DonFusili, well yes, partially. Our entire counting system is base 10 simply because we have 10 fingers. That's why we refer to numbers that are multiples of 10 as "round numbers". Not only that, but a supplied voltage is always going to be +/- 5-10V around the nominal supply so again, 127V is very specific when compared to a "round number" of 120 or 130. – Darren Sep 27 '18 at 14:29
• Don was providing a Socratic question... Anyways Saudi Arabia also has 127 volts as well. The reasons is just for convention. This question has the same answer on why we Americans have 120 volts instead of 127 volts or why the majority of Europe has 220 to 240 volts. The reason for our differences most likely has to do with the machines we make in our specific country that generate a specific voltage. – KingDuken Sep 27 '18 at 14:34
• Sure, but electricity generation is mainly based on which one of the N working ones that is stable and mature enough a country decided to copy. I'd have understood this question better if your reasoning was "I'd expect it to be the same as the US in case they need to transfer power across the border". I don't see why someone would care about having a round number just for having a round number's sake. – DonFusili Sep 27 '18 at 14:34
• Also, as an aside, I prefer that the people that have control over my electric supply don't have more problems with an interval centered on 127 than one centered on 120. – DonFusili Sep 27 '18 at 14:37