Voltage Ratings: 110/115/120, 220/230/240 or 440/460/480

[jim dungar]

For Wye systems the letter Y is included in the descriptor which I believe is an IEEE standard such as 208Y/120 or 480Y/277. It's also directly from the NEC, a few examples:

Most utilities do not follow this standard nomenclature. But those of us that depend on the NEC should.

 

[JakupstateNY]

REA crews traveled through the American countryside, bringing teams of electricians along with them. The electricians added wiring to houses and barns to utilize the newly available power provided by the line crews. A standard REA installation in a house (post World War II) consisted of:

• A 60 amp, 230 volt fuse panel, with:

1. A 60 amp range circuit
2. A 20 amp kitchen circuit
3. Two or three 15 amp lighting circuits

A ceiling-mounted light fixture was installed in each room, usually controlled by a single switch mounted near a door. At most, one outlet was installed per room, since plug-connected appliances were expensive and uncommon.
Wiring was performed using type NM (nonmetallic
sheathed cable), insulated with asbestos-reinforced rubber covered with jute and tar.

History of REA

I also like to use this chart:
View attachment 2557797

Learning daily, thank you

 

[TX+ MASTER#4544]

drcampbell said....

I'm still laughing at ".....hold my beer and watch this" That was funny!
I'm sure you were referring to the three squiggly lines, coils.

Now, show me a corner grounded transformer......and the voltage at the corner.
Then have another one on me.

As a certain poster often says.....cheers.

Thanks for the humor.
Comments accepted.
TX+MASTER#4544

 

[kingpb]

But in the end, people will still call it 120/208, and 277/480. And every time the drawings saw 120/208V, I I know they mean 208Y/120V will issue a Change order.

 

[hornetd]

What an absolute bloody mess....................................

The great thing about standards is that there are so many to choose from.

Tom Horne

 

[Besoeker3]

The great thing about standards is that there are so many to choose from.

Tom Horne

Not so much in Europe. Residential is 230Vac. Industrial is 400/230V. There are specials, for example in Paper Mills, so obviously they are not standards

 

[hornetd]

I'm sure that you are aware that we were discussing the variations in North American service delivery voltages. Just because Europe got it's collective act together doesn't change the plethora of voltages used in delivering power to premises on this continent. Europe's distribution development had the advantage of the mistakes that had been made earlier in the development of the North American systems. As is often true the competitive rush to be early to market caused North American investor owned utility ventures to make mistakes that still cause problems today.

I believe that the Multi-Grounded Neutral of most North American distribution systems is a good example of one of those errors in fundamental design. The stray current problems that continue today cause illness and production losses in domesticated animal live stock. More importantly such stray neutral currents are a major contributor to fresh water paralytic drowning deaths.

For all I know Multi-Grounded Neutral systems may also be in use in Europe but the additional characteristic of the North American multi-grounded neutral system is that the neutral is common to both the Distribution and Secondary Distribution systems. By that I mean that the same neutral is connected to both windings of the Secondary Distribution transformers. That practice allows primary distribution currents to flow into the earth at any of the grounding points in the distribution system, including those located on private premises. The well documented effects of those stray currents on dairy production alone is enough to demonstrate the stray current effects of a multi-grounded AND Distribution and delivery common neutral system. I would benefit from a new thread on how neural currents of both voltage sets are handled in Europe. Perhaps others would to.

There are still a few places in North America were the delivered voltage is 100 volts DC. Admittedly those are mostly tiny island communities were the power system was originally privately owned shared generation for vacation homes of the wealthy but the fact that several such systems still exist is an example of how diverse North American service voltages are.

The principle reason that the service voltage in many places rose from 100 volts to 110 volts was that Edison's initial DC power plant ran on the standard telegraph outside line voltage of the time which was 100 volts. Designs for the Dynamos used to produce larger amounts of 100 volt DC were already in production and readily available for those DC distribution systems. Edison already had a number of patents on improvements to telegraphy technology which allowed up to 4 signals on a single telegraph wire. Since he was first out of the gate with a public electrical system he turned to what he was already familiar with from his work in telegraphy. As use increased, and electric lighting began displacing gas lights, the Manhattan electrical system began to become overloaded. To avoid the expense of constructing additional distribution wiring Edison raised the voltage in order to deliver more watts at the existing current capacity of his Manhattan outside plant distribution system. With a great many premise electrical systems then at the limit of the insulation materials used in the earlier installations further increases in voltages higher than 110 volts for DC systems were not practical. When the "current war" ended with the defeat of Edison's DC distribution by Westinghouse's, Tesla invented, AC power the installation of new DC systems came to a virtual halt with only a few existing systems remaining as built. Many of the earlier DC systems were eventually converted to AC. The increase in the service voltage to 120/240 1Ø was again the result of use increasing faster than the expansion of electrical distribution systems. With the reduction of the arcing inherent in DC switching the voltage delivered to customer premises could be raised again to its present 120/240 volts. That is all fairly well documented electrical history but it doesn't explain the wildly different distribution voltage systems.

Tom Horne

 

[Besoeker3]

I'm sure that you are aware that we were discussing the variations in North American service delivery voltages. Just because Europe got it's collective act together doesn't change the plethora of voltages used in delivering power to premises on this continent. Europe's distribution development had the advantage of the mistakes that had been made earlier in the development of the North American systems. As is often true the competitive rush to be early to market caused North American investor owned utility ventures to make mistakes that still cause problems today.

Tom Horne

European systems have developed over many years and now, in a few decades, it has been rationalised and simpler. Can you same for USA?

 

[hornetd]

European systems have developed over many years and now, in a few decades, it has been rationalized and simpler. Can you same for USA?

No! I thought it was clear that I was saying the exact opposite. I've not studied European electrical distribution practices in any depth but at first blush the European system appears to be harmonized to a great degree. The North American system appears to me to be in a great deal of disarray. I sincerely did not mean any disrespect to you or the European system. I was, however inadequately, trying to express my admiration of the degree of standardization Europe seems to have developed in many areas of technology, not to mention commerce, currency...

Tom Horne

 

[infinity]

No! I thought it was clear that I was saying the exact opposite

I took it as you meant the opposite as well. I don't find the US standards to be completely lacking. We do have several standard nominal voltage systems. I find the use of the 230 volt motor voltage to be confusing. It is okay for 208, what about 240? We don't use 230 volt systems so is it neither or both ?

 

[Besoeker3]

No! I thought it was clear that I was saying the exact opposite. I've not studied European electrical distribution practices in any depth but at first blush the European system appears to be harmonized to a great degree. The North American system appears to me to be in a great deal of disarray. I sincerely did not mean any disrespect to you or the European system. I was, however inadequately, trying to express my admiration of the degree of standardization Europe seems to have developed in many areas of technology, not to mention commerce, currency...

Tom Horne

I'm have a few changes in my life here in UK - I'm 77 years old. We used to have currency in pounds in shillings and pence. We fixed that with decimal currency, much simpler. Then we got metric units (more accurately System International). Now we have kilos rather than pounds and ounces. Again, it is simpler. But there are still people who want old units - go to a pub and get a pint of beer but have a wine and get 250 ml

Enough...........

 

[roger]

No! I thought it was clear that I was saying the exact opposite.

Tom Horne

Hope you don't take this wrong but it might be time to consider being concise and to the point instead of typing a short story that's hard to read and follow.

 

[hornetd]

I took it as you meant the opposite as well. I don't find the US standards to be completely lacking. We do have several standard nominal voltage systems. I find the use of the 230 volt motor voltage to be confusing. It is okay for 208, what about 240? We don't use 230 volt systems so is it neither or both ?

The voltage on the name plate of any NEMA rated load is +- 10% so at 230 volts you can go up to 253 volts and down to 207 volts. That means that the allowable range of voltages is 207 to 253. So it does indeed cover all of the commonly delivered service voltages to residences. Thus the answer is BOTH.

Tom Horne

 

[markwilkie]

This subject comes up a LOT in this and other forums, so I thought it would be a good idea to make it a "Sticky" that can be found and referred to easily when it comes up.

There are two "standards" for voltage in North America depending on which END of the wire you are looking at; "Distribution Voltage" (also called "Service Voltage") and "Utilization Voltage", both set forth in ANSI (American National Standards Institute) Standard number C84.1, backed up by IEEE (Institute of Electrical and Electronics Engineers).

The official Distribution Voltage standard for single phase is 120 and 240V, for 3 phase it is 208, 240, 480 and 600. It has been this way since the 1930s after the REA (Rural Electrification Act) during the Great Depression went to bring electricity to farms and rural areas, because the Utilities all did what they wanted to and they didn't see enough profit in it. But because each utility was different at the time, (i.e. 110, 115, 117, 120, 125, etc. etc.), and the REA didn't want to have their service trucks carry around multiple voltage ratings, they picked a "middle ground" of 120/240V and called that the standard. It has been that way since. Later on, standards for the Utility industry came along and added that no matter what they give you, it has to be within +-5%. So for a 120V system, that is between 114V and 126V; for 240V it is 228 to 252V, etc. etc. However many of the older systems still deliver what they used to deliver, regardless of what it is officially called, so yes, there are still pockets of 110V, 220V and 440V out there.

For that reason, industry organizations for manufacturers, such as NEMA (National Electrical Manufacturers Assoc.) developed their OWN standards for the devices that use electricity, and their standard was +-10%, but based on a LOWER voltage, because there is an expected voltage drop from the Service Entrance to where the device connects. So for 120V Distribution, the Utilization voltage is 115V; for 240V it is 230V, for 208V it is 200V, for 480V it is 460V and for 600V it is 575V.

So how that works out is that a MOTOR for example will be built for 230V, +-10%, so it can accept anything from 207 to 253, and because the Distribution Voltage is 228 to 252V, it fits right in. But also if the Utility was still putting out 220V instead of 240V, the LOW end of their range would be 220-5%, so 209V, still within the acceptable range of the Utilization standard.

People however are not swift on the change though, so LOTS of people still refer to residential as being 110/220, or 115/230 or 120/240 (inset joke from the movie "The Money Pit" where Michel Keaton says "220/221.whatever it takes..."). But OFFICIALLY, it is supposed to be 120/240V.

While we are on the subject of "officialdom"; When describing distribution systems that have more than one voltage available, there is a "convention" in the description that should be used to help avoid confusion.

• If the subject is SINGLE PHASE, the LOWER voltage is listed first, followed by the higher . So a residential single phase system is described as "120/240V".
• If the subject is THREE PHASE, the HIGHER voltage is listed first, followed by the lower. So 480/277V would be correct, 277/480V would not. This is especially important because we have 240/120V 3 phase 4 wire systems available. So by calling it 240/120V you are differentiating it as three phase, compared to 120/240V being single phase.

I agree that this is great info. I knew the 10% but didnt know the history. Also i didnt know about the 120/240,1ph.vs.240/120,3ph. Thanks!

 

[kingpb]

Very well written and described.
I will add one additional tidbit regarding 208V

You can have a 120/208V system that is derived from a 208Y/120V system. It is simply when you utilize a 2-pole circuit (2 phases) for your service from a a three phase circuit.

 

[LarryFine]

You can have a 120/208V system that is derived from a 208Y/120V system. It is simply when you utilize a 2-pole circuit (2 phases) for your service from a a three phase circuit.

Yep, like is often done in apartment buildings. I refer to it as 120/208v 1ph.

 

[garbo]

Learning daily, thank you

Learning daily, thank you

Read the history of the REA. Can remember purchasing the old cloth covered NM cable around 1966-67 then they offered the plastic jacket for think it was 50¢ or a $1 more for a 250' roll of 14/2.First time that I ever heard that it contained hazardous asbestos. Back then we often worked in old unoccupied houses with no running water so just wiped your dirty hands on your pants before eating a packed lunch.

 

[hornetd]

Back then we often worked in old unoccupied houses with no running water so just wiped your dirty hands on your pants before eating a packed lunch.

And all that time the other guys thought that the reason I carried 4 sets of nitrile gloves was in case I had a really busy day involving legally required assistance to people who got hurt of sick. Yes I was keeping my hands clean but it wasn't only for the patients benefit.

Funny note: The first line of every single state approved emergency treatment protocol was "Calm and reassure the patient." That included the one for performing Cardio Pulmonary Resuscitation (CPR). The second line of which is "Check for consciousness."

I hauled a nurses aid off a patient that she was doing compressions on because the patient kept saying "stop that it hurts." As I moved this person away from the patient I said "For future reference we do not perform CPR on patients who object my dear."

Tom Horne

 

[don_resqcapt19]

I took it as you meant the opposite as well. I don't find the US standards to be completely lacking. We do have several standard nominal voltage systems. I find the use of the 230 volt motor voltage to be confusing. It is okay for 208, what about 240? We don't use 230 volt systems so is it neither or both ?

A motor with a nameplate voltage of 230 is intended to be used on a nominal 240 volt system. It is not intended to be used on a nominal 208 volt system unless so marked on the nameplate. The nameplate voltage for a motor intended to be used on a 208 volt system is 200 volts.
This is the difference between the utilization equipment nameplate voltages and the nominal system voltages.

 

[tortuga]

The nameplate voltage for a motor intended to be used on a 208 volt system is 200 volts.

For 208Y three phase motors under ~10HP what I typically see is manufacturers cheating and sell you a 220/440V motor.
They call it a "tri-voltage", and stamp the nameplate 208-230V / 460V and thats when I use the 208V table in 430.
When I see a a tri-voltage nameplate like that I just think of it as a 220/440V rated motor.
To me a "tri-voltage" motor is not truly rated for '200V' and your voltage drop calcs need to account for that, as they probably wont really run well with voltage sags allowed in the ANSI C84 spec for 208Y/120 nominal system.
A true '200V' motor designed for a 208Y/120 nominal system would have a 200V nameplate indicating it does comply with ANSI C84 voltage range B minimum of 180Y/104V and then I use the 200V table.