What is voltage supply in USA ,,,,, 110 or 120v? I've seen both .. Wiich one is correct?
Thanks
See Section 220-2 in the National Electrical Code, we have others voltages that we use in the US.
I've seen a lot of material which quotes 117V, saying that it's the average nominal voltage across the U.S. That's mostly older books though. ??
Mike,
Some others may say 115 and some devices and appliances say they're rated @ 125v. They are all really talking about the same thing. Actual voltage at different locations I've seen vary from 110 to 125 so Paul's 117 average makes sense.
Happy New Year!
Bill
As far as I'm concerned we have:
120
208
240
277
480
However, I was once told that supply voltages has slowly been boosted over the years. I don't know if it's true, but it could explain some old motors with 440 volt ratings. Also, some older equipment seems to have 110 or 220 on the nameplates.
And let's not forget that pesky 460 rating. Where in the world did that come from?
How about it old timers? (older-than-me timers)
BTW,
Anyone here use 575?
My vote goes to Elzappr, Joe, and Redsy. Article 220-2 for calcutations. Notice "Voltage (of a circuit)", and "Voltage, Nominal" in article 100, and I would also have a look at Article 110-4. Nominal voltages are just as Redsy says.
Another example can be found in Article 430, Table 430.150
The voltages listed are rated motor voltages. The currents listed shall be permitted for system voltage ranges of 110 to 120, 220 to 240, 440 to 480, and 550 to 600 volts.
In Canada we use 575v motors with a nominal supply of 600. The way i understand single phase residential voltage is as follows.we have 240v coming from the pole with a maximum allowable 5 volt drop for the entire service.110,115,220,230 etc is the equipment name plate voltage rating.when installing equipment the supply must be within 10% of this name plate rating.
We have 122 to 123 volts TRMS per leg on average here... I've seen as high as 127, and never lower than 118, unless major voltage drop due to distance/current/wire size is occurring, which I try to avoid.
120V light bulbs are short lived here.
Since 1949 (see ANSI C84.1-1989), the nominal system voltages in the US are: 120V, 208V, 240V, 480V, and 600V. There are +/- tolerances for these voltages, but they are on a utility by utility basis.
The NEC says "... The actual voltage at which a system operates can vary from the nominal within a range that permits satisfactory operation of the equipment."
Motor manufacturers have decided to rate their devices at utilization voltages of 110V, 200V, 230V, 460V, 575V. Some end use appliance manufacturers rate their equipment at maximum voltages such as 125V.
[This message has been edited by JBD (edited 01-02-2002).]