What are the 3 phase voltages in the USA ? 3

[MarkusPort]

We have to install UV dryers in the U.S.A.

In Europe, 3 phase + ground (Y) is common in industrial sites. Phase to phase around 400 VAC, ground to phase 230 VAC.

What is common in the U.S.A. One hears, 480 VAC delta, no ground.

Is there a standard ?

 

[rbulsara]

For systems 600V and less:

Most common in the USA is 480Y/277 , 3phase, 4 wire grounded system for equipment in commercial and industrial sytems. Commercial lighting normally is 277V.

Convenience outlets, whether residential, commercial or industrial are always 120V, a part of 208Y/120V, Y system. Therefore, a system of step-down transformers , 480V delta to 208Y/120V is always present in commercial and industrial systems.

As with any other place, exceptions are always present which include ungroundned or groudned delta systems. Always check with your clients.

And for your further informatin:

Resiential systems are normally fed by 2 phases and a neutral (single phase, 3 wire) which in fact is part of a 208Y/120V , Y grounded system. 480/277 is never used in the residential systems.

Many older residential systems would have 240/120V, single phase 3 wire systems.

Hope this helps you cause.

 

[alehman]

In my part of the U.S. (midwest), residential service is nearly always 240/120, single phase, 3 wire. 208Y/120 is uncommon. A few of the largest residences do have 480Y/277 for large air conditioning systems.

Grounded 480Y/277 is standard for larger commercial and industrial applications, however many small commercial services (esp. retail) are 240/120 single phase 3 wire or 208Y/120 3 phase, 4 wire.

Some industrial installations use 480Y, with high-resistance grounding. Ungrounded 480 is very rare except in a few old industrial applications. Many old industrial systems are 240V 3-phase delta, either ungrounded or with B phase grounded.

 

[busbar]

If you need something “chiseled in stone” about US voltages, search for ARI Standard 110-2002. Last time I checked, it was free, whereas the official document is ANSI Standard C84.1-1995 that costs $30. For low voltage, they seem identical with one exception. For specific regions, electric utilities generally publish availability in their online “service conditions.” {There are no small number of electric utilities on the North American continent.} For typical industrial-machinery branch and feeder circuits, don’t count on a neutral conductor routinely carried with phase conductors.

120V control power is usually derived from a machine-tool control power transformer served from fused [208-600V] line conductors served to equipment. Where 230V control may be tapped from a 400Y 4-wire circuit, a similar 277V prectice is rare.

 

[Modula2]

MarkusPort, 3 phase + ground (Y) is the most common in industrial sites. Delta is rare but may exist in much older installations.

Most common is Phase to phase nominal of 480 VAC, ground to phase 277 VAC.

For smaller systems, Phase to phase 208 VAC, ground to phase 120 VAC.

For larger systems, Phase to phase 4160 VAC, ground to phase 2400 VAC. (probably resistance grounded neutral at this level).

(For larger systems, Phase to phase 13800 VAC, and so on).

 

[Kiribanda]

Hi MarkusPort,

The best method is to refer the correct standard to get full information. ANSI C84.1-1995 indicates full details of voltage systems for 60 Hz (US & Canada) and also describes useful definitions for LV systems.

Regards!

Kiribanda

 

[cuky2000]

If equipment is rated for different voltage and frequency different than 60 Hz, verify if any derating is require.

For specific application and available site voltage consult with the local utility company regarding interconnection for the intended motor load. Typical requirement are described in the enclose site.

http://www.duquesnelight.com/connections/esir16.htm

http://www.duquesnelight.com/connections/esir15.htm

http://www.duquesnelight.com/connections/esir36.htm

 

[jbartos]

Suggestion: I see that you are using the neutral as a ground conductor. This appears to be typical in Europe. The neutral is not used for grounding in USA since the code (NFPA 70 National Electrical Code) allows to ground neutral at one location only, i.e. at the service entrance. Often, a separate ground conductor is installed for the equipment grounding to have the ground return path properly conductive.

 

[lyledunn]

This sort of begs the question about international standardization. Are we progressing at all? I know that in Europe, CENELEC are making some headway in levelling the playing field, although often with mech reluctance from national interests, (the British socket outlet being a prime example). Much of their deliberations are based on IEC material but it would seem that the good old usofa is as remote from european standards as ever!

Regards,

Lyledunn

 

[cuky2000]

There had been small progress in standardization but in my opinion insignificant. Standardization is a good idea but very difficult to achieve because changes could be associated with significant cost.

For instance, I do not know how will be possible to change from 60 Hz to 50 Hz in the US. Other example is to change in the US typical residential voltage from 110 V to 220V as many other countries in Europe.

There are issues such as NEC compliances, construction regulation and building codes requirement, insurance polices, testing, UL certification, engineering standards, safaty practice, etc. that also require to be changed.

 

[twosockets]

To all,

There is a tremendous variety of electrical services in the U.S. Here is a short list of some of the more unusual electrical services <1000 volts that I have personally encountered in the last few years:

240-volt 2-wire with end ground
277-volt 2-wire with end ground
480-volt 2-wire with end ground
240/120-volt 3-wire 1 phase with end ground
480/240-volt 3-wire 1 phase with end ground
416/240-volt 4-wire wye with grounded neutral
416/240-volt 4-wire wye with ungrounded neutral
416/240-volt 4-wire wye with grounded phase
480/277-volt 4-wire wye with grounded phase
480/240-volt 6-wire delta with one center tap grounded
480/240-volt 5-wire delta with one center tap grounded
480/240-volt 6-wire delta with one corner grounded
830/480-volt 4-wire wye with grounded neutral
120-volt 3-wire grounded delta
120-volt 3-wire ungrounded delta

 

[davidbeach]

One thing to remember when comparing the disparate American &quot;standards&quot; with the much more uniform European approach is that much of the European infrastructure had to be extensively rebuilt in the mid 1940's while we have not had to do anything similar. Changing system configurations just for the sake increasing standardization is extremely expensive. It is common though for utilities to support existing installations that they would not allow as new, things move slowly towards some degree of standardization.

 

[alehman]

In the U.S. electrical codes are typically adopted and enforced by the local city or county (termed authority having jurisdiction). The NEC is generally the model, but many AHJs have their own ammendments. Also, different editions of the NEC are in force by different AHJ's. You have to find out what edition and ammendments apply to any given area. A few major cities maintain their own electrical codes which are usually some variation of an old version of the NEC. Yes, it is confusing.

 

[jbartos]

Suggestion to the original posting marked ///\\We have to install UV dryers in the U.S.A.

In Europe, 3 phase + ground (Y) is common in industrial sites. Phase to phase around 400 VAC, ground to phase 230 VAC.
///Europe has somewhat stricter the power distribution system voltages with fewer deviations than USA.\\What is common in the U.S.A. One hears, 480 VAC delta, no ground.
///This is very old system, nowadays replaced by 480/277VAC grounded wye in most cases. The ungrounded 480V or similar system voltages are used for dedicated loads, only. The ungrounded system voltages experience detrimental transient overvoltages due to arcing.\\\

 

[advidana]

What about changing everything to USA 60 hz voltage standards and using the USA NEC. I think that is the best bet.

My point is it would cost way to much money for everybody to convert to usa standards and vise vera. I like the idea of standardization if it doesn't cost me any money, let the other guy pay for it, but that will not happen.

 

[ScottyUK]

advidana,

Europe is faced with a similar problem now that the nominal voltage is 230V. The tolerances on this nominal voltage have been widened, at least for the medium-term future, so that the UK with 240V and the rest of Europe with 220V don't have to replace much of their distribution infrastructure to comply. The cost of such wholesale replacement of equipment would, as you say, cost way too much.

 

[lengould]

We have similar issues in Canada to what you're having, e.g. every industrial plant service here is 600V nominal (usually 575-585 delta ungrounded at least up to 15 yrs ago) and every time production gets excited and installs a new US machine we either replace all motors or put a dedicated stepdown transformer at the machine. The transformer may be the way to go for you with electronics, gives you a level of isolation, you can choose your grounding strategy. You may need a special inspection if you do anything very unusual with grounding, check with the provider/ authority.

Standardization? Ask every industry / commercial building / residence to rewire to a new voltage? Not on, I'd guess, except maybe a 50 yr+ dual standard strategy. I must say, though, those British 240V &quot;ring mains&quot; sure have a lot of advantages for install cost.