Does 220V actually exist?

The phrase "two-twenty" is essentially a leftover from the earliest days of electricity in the US when power was delivered at 110V, doubled when measuring between both hots of the Edison system to 220V. Over the years the voltage has been increased somewhat to nominal 115V, to 117V, to 120V, with the voltage between the two hots double this, of course. The electricians just never adopted the voltage of the decade lingo, or maybe "two-twenty" sounds cooler than "two-thirty-four" or "two-forty".

Somewhat related: I noticed the warning on the third rail of the NYC area commuter railroads reads "Danger 700 Volts". I always thought it was 600 volts. Going from 600 to 700 volts is a larger percentage change than from 110-120V, so was this an actual upgrade of the system to increase the voltage by 17%?

(I also noticed the warning signs on the catenary railroad reads 12,000 volts for newer equipment and 11,000 volts for the older stuff, much of which looks really old. This would make sense as part of the overall voltage increase, being 100 times the nominal wall outlet voltage)

Too many folks were ignoring the 600 volt sign, so they upped it to 700 volts. Kind of like the homeland security color schemes.

I thought it came from the fifty year old man who divorced his wife and took up with two twenty year old girl friends. He soon found that he wasn't wired for 220.

But it's interesting that there are some significant changes if the 'nominal voltage' is above or below 600V. At least in OSHA safety requirements...

So does working on the 'new' equipment require the safety requirements for "nominal voltage above 600V"??

daestrom

Since 600V is the line between low voltage and medium voltage, then if it is actually 700V I would think it does. Even if it is really 600V, how does a worker know that, if the sign says 700? I think OSHA would say that you must consider it as 700V. Just my opinion.

Ben Miller

FWIW, the wiki page

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