Is three phase the same as 220V in home electrical systems?
Homes have single phase, both the 120V and 240V. In the case of 240V, there are two hot wires at opposite phases - 180 degrees apart - and a ground. Three phase has three hot wires each 120 degrees apart in phase and a ground. As far as I know, residences can’t get three phase. Also, I’ve never seen 240V three phase. At work, we have 480V three phase.
No, they’re not the same. If you want to use equipment that requires three-phase power, you can’t run it off of a normal residential electrical service.
I believe you can get a rotary converter to convert single phase to three phase.
No, it’s not.
There is almost no residential application that will benefit from running 3 phase power, and none of them are worth the cost of running a 3 phase line to your home. 3 phase is primarily a heavy commercial, manufacturing and industrial service.
As answered above, no, it’s not the same.
Now, what brought up the question? Idle curisity, or a desire to run a huge power tool or welder at home?
It’s often possible to change some taps on large motors and welders to be able to use the machine on either 240 or 3-phase.
Unless…you live in a part of the country, such as some areas of New York State, where instead of being fed 240 V split phase, houses are fed two phases of a 208 V three-phase distribution. The line-ground voltage of a three-phase service is the line-line voltage times the square root of three, which for 208 is–ta da–120 V.
Some larger US homes have 208/120V 3 phase 4 wire. I’ve seen it although these are very big houses.
In the US, there are two common voltage systems used in commercial, industrial and large residential. 480(phase to phase)/277V(phase to neutral) and 208(phase to phase)/120V(phase to neutral). These are 4 wire systems. 3 phase wires and a neutral.
In most US residential services, one gets 120/240 which is simply two 120V phases 180 degrees apart - 3 wire (2 hots, 1 neutral).
In the UK (not that anyone asked), house power is 240V single phase. Everything including the kettle and the electric blanket is 240V. Commercial power is 415/240 3 phase 4 wire.
Do you have a three-phase piece of equipment you need to run off of 220V? There are a few ways to do that depending on the application.
In the UK (not that anyone asked) house power was changed from 240 to 230 V to make it the same as the continent which went from 220 to 230. So now pretty much all countries that used to be 220 or 240 are now all 230 (+/- 10%).
My brother looked at getting 3 phase at his house to run some commercial wood working equipment. It would cost $120,000 to just install the service. They would have had to run cable from several blocks away.
-Otanx
I think that it also depends on your anticipated usage.
A couple of years ago, I oversaw the installation of a sewage pumping station in a residential neighborhood, which required 3-phase AC power. The nearest three-phase power stopped a few blocks away. The electric utility had to install two new poles and replace another pole to bring 3-phase power to the pumping station property line. Interestingly, the utility paid for all of this. (They also took about 9 months to get it done, but that’s a different story.) The explanation I got was that the utility would make back their investment based on the anticipated usage of the 3-phase sewage pumps which would be cycling on-and-off 24/7/365.
The municipality did have to pay for extending power (via an underground conduit) from the pole at the property line to the pumping station proper.
A rotary converter (basically a single-phase motor driving a three-phase generator) would be a whole hell of a lot cheaper. A 200-kW unit could run your whole house using a 200-amp service at capacity and still cost 1/5 as much; and just for wood-working equipment he probably wouldn’t need nearly that much.
Except that the question is “Is three phase the same as 220V in home electrical systems?” I don’t know where you get 220 V. 208 V yes but not 220.
In Europe it is also common to have 230 V supplied between neutral and one phase but each residence gets a single phase so they still do not have three phase supply which would require a major change in the meter and supply cabling. Equating any voltage with three phase supply is meaningless.
In the DC area and other parts of the USA I have seen the usual thing in residential areas is for three phase high voltage to run along the top of the posts, the low voltage distribution just below that and then phone, cable, etc. below that. So three phase power is available just in front of my house in case I need it for the powerful orgasmatron I am building.
There are two ways that power is supplied to homes in the U.S. By far, the most common is a single phase center tapped transformer, which gives you a line to neutral voltage of 120 volts and a line to line voltage of 240 volts.
Far less common, but still in use, is where your house gets fed two phases from a three phase system. This is what QED is referring to. Technically, it’s not the same as 3 phase power, but you are getting two out of 3 legs of a 3 phase system, so some people do call it a 3 phase system. In this case, the line to neutral voltage is still 120 volts, but the line to line voltage is only 208.
Having 208 instead of 240 is an issue for things like an electric oven or an electric dryer. Your oven will take longer to heat up and your dryer will take longer to dry clothes if they are given 208 instead of 240.
In some areas you’ll get all three phases available, like you described. In others, like where I live, they separate the three phases and run one phase to one neighborhood, another to the next neighborhood over, etc.
No orgasmatron for me.
It’s called additional related information. Most people seem to appreciate it since they can learn things they might not otherwise if the thread stays exactly on point. If you don’t like it, that’s too damn bad for you.
No, it is not that I don’t like anything. It is that your answer was wrong.
You were answering to this post:
And your answer was.
Which contradicts gotpasswords and which says and means and implies that if you live in some areas of the country then “three phase the same as 220V” which is clearly not true. gotpasswords was right and your contradiction to his post is wrong. There is no way around it. Maybe you meant something else but what you said is just not correct.
Whatever, dude.
Most such equipment can be adjusted internally to run from either 3 phase/208V or 1 phase/240V. Usually just a matter of moving the wire connections from one set of terminals to another under the cover of the machine.
I’ve done this on a couple of machines for my brothers’ wood shop – it’s not hard at all, if the machine allows it.
Or you could build your own.
If I really needed one I would buy it but it’s an interesting article.