What is the domestic voltage in the USA

[Marty8]

Strange question I know. I'm from England and will be coming over to the States next week. For some reason I had the idea that the US runs on 110v D.C. although I can't think of a good reason for using DC on a domestic supply. Seen a few things that suggest 110V A.C., but I was absolutely convinced that someone once told me it was DC in USA.

Can someone please clear this up for me!

Cheers and sorry about the dumb question ;-)

Marty

 

[Howard]

It's AC.

 

[Sunner]

I thought it was 115, of course this info comes from the back off PSU's

 

[jinsonxu]

I thought it was a basic concept from high school physics class that our power stations supply us with AC voltage and not DC?

 

[oldandquitemad]

in addition to our AC voltages, be aware the we use 60Hz power also.

 

[Dameon]

ACtually, originally Thomas Edison fought very hard to have the US wired with DC, and was quite angry when AC current won over DC.

Quick history tidbit.

 

[Buddha Bart]

115-120v AC at 60hz

bart

 

[Marty8]

Thanks guys.

As I said, it doesn't make any sense for it to be DC - don't know where I picked that idea up from :0

Marty

 

[radiocore]

hehe, yeah...115, I'm actually going to be in London in two weeks for the rest of the semester. Whats the voltage over there. =)

 

[Marty8]

240V AC 50Hz

Hope you have a good time in England.

Marty

 

[dkozloski]

The argument of AC vs. DC was not settled until fairly recent times and the last holdout was a small DC generation facility in the heart of New York City. Thomas Edison had his money invested in DC and was a very vain man that could not admit he was wrong. Nicolai Tesla was the advocate for AC and was clearly correct but had to fight the underhanded tactics of the "great" Edison. DC power required a generation facility every few miles because at that time huge wires were required to transmit high power by DC.
Everything has turned full circle and now the highest voltage, most efficient, long distance transmission lines are DC which was made possible with modern solid state technology.

 

[RossGr]

This is first that I have heard of DC being used for High Voltage transmission lines. When did the happen? What is your source of that info, frankly I doubt it. The power grid in the Pac Northwest still uses transformers. As long as you are using a transformer you need AC.

If 1900 is recent then the US "recently" dropped DC as a option.
Edison developed the electric chair useing Westinghouse AC generators with the sole idea of showing how "dangerous" AC is. Hoping to sway public opinion aginst it!

 

[thorin]

115-120v @ 60Hz.

Thorin

 

[dkozloski]

RossGr, The last Edison DC plant was shut down in the 1980's. It was being used for one customer in NYC. The high voltage transmission lines in Northern Europe run at 750KV plus DC. This eliminates losses due to induction into material surrounding the transmission line. i.e. running your barb wire fence under the HV line and robbing current with the resulting air core transformer.
Solid state technology is used to rectify the AC to DC after it has been bumped up in voltage by a transformer. On the other end, solid state switching produces the AC required for local distribution. I read about this in Scientific American magazine quite a while ago. The key to the whole thing was to be able to have the switching take place as the current goes through zero in the AC cycle to eliminate arcing.
The underlying infrastructure in the Northwest was established in the 1930's, long before the solid state revolution.
The Canadians know all about modern HVDC transmission lines. This is the technology that made their power grid possible.

 

[Mark R]

240V AC 50Hz

Actually, it's 230 V. It used to be 240 V +/- 8%.

However, due to integration with Europe, it was decided to change to 230 V (which the rest of Europe uses).

Of course, no one actually was going to change anything, so the voltage is now 230 V -8% +11%. This means that although the voltage is nominally different, the acceptable voltage range includes the entirety of the old range (plus more).

 

[hymy]

Actually U.S. power can be as low as 108. I don't understand it, but the power where I work comes in 108 or 216 if you double it. Its weird.

 

[Howard]

LOL

Edison, 'during his campaign' advocating DC power, went around the country shocking sheep with AC power. What an ass!

 

[radiocore]

THanks Marty, hope you have good time here too =)

I only have one question though. On my power supply, theres a switch...currently on 115, and the other option is 220. Will I be able to just flip it and plug it in in London without it frying my computer? Or would it be safer to just get a converter?

Thanks for all the great information guys, this really helps me pick up lots of tidbits.

-Radiocore->>

 

[Zorba]

When it comes into a home it is 120v AC and 240 AC. The 120v is what comes out of the wall.

 

[Marty8]

Radiocore...

I'd be amazed if your 220V AC setting didn't work over here. I'm sure that's within the normal tolerance on the domestic supply (see Mark's earlier post about 230V). I don't believe that the difference in AC frequency between USA and England is going to be a problem with your PC power supply either.

I've also just checked some of the PC's in the office here... their power supplies say Input: 220 to 240V, or there's a switch to select 110 to 120V (presumably for USA).

Marty

 

[Sunner]

Just about every PSU Ive seen in my entire life has had a switch between 115/230, and I've had first hand experience with switching between the two(In the school I went to we had both 115 and 230 plugs for educational purposes, but 230 is the standard here) with no problems.

One of the funniest thins Ive seen was when a guy in one of the computer rooms in the school I went to switched from 230 to 115 while the comp was running, damn he got scared $hitless

 

[MadRat]

Isn't a brownout not considered until we drop to 90v 60Hz in the U.S.?