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Every time I hear an electrician using those terms, I'm bummed out. Nobody who's spent years reading meters should say "110."
My thoughts. Old electricians and GCs seem to be the major hold outs. Should say anyone that has used a DIGITAL meter should say 120/240. Those old Simpson analogs were good, but that needle and tiny writing aren't as "Eureka" instilling as a digital meter.

What I have never understood is why it goes 110/220 ,110/208, 277/480 and 550v. That's how my grandfather has always talked about voltages; and it never made sense to me. Why wouldn't it be 110/191 and 254/ 440? For Pete's sake, be consistent!
 

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Every time I hear an electrician using those terms, I'm bummed out. Nobody who's spent years reading meters should say "110."
I have always said 120/208, I see voltages that are across the spectrum from a low of 89/154 to 130/225 but average is 115/199 to 124/214. Her we have some 265/460 the transformers come in at 120/208 and no one changes the taps until we get called in for low voltage issues these secondary's are generally 116/201

ON 3-phase Wye systems
 

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motors and controls.........
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Do you guys ever do 55v to ground 2 phase, giving 110 across phases?
I haven't seen that one yet, but I've seen plenty of potential transformer voltages of 69/120 Wye derived from high voltage (over 35KV) systems.

Also, 120 (or thereabouts) open ∆ grounded B is common for low and medium voltage potential transformers. PTs have voltage ratios, so you might get 120, 115 or some other odd voltage depending on the primary voltage.
 

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History lesson:

"110V" is a legacy resulting from systems in the earliest days of electrification using AC distribution systems developed by Tesla for Westinhghouse. They had to compete with Edison, who was promoting DC for his electric lights, and through a series of experiments, he had settled on 100VDC as a compromised between safety and lumen output. So to make people willing to use AC, Westinghouse decided on 110VAC as a standard. I've read somewhere that he may have started out with 100VAC, but changed it to 110 because it sounded "better" than 100, kind of like the volume knob that goes to 11.

In the early days, once people started jumping all over the concept of long distance distribution of AC, there were different system voltages at almost every provider, ranging everywhere from 100-135V. That presented a challenge for equipment providers, especially those using motors, because a motor designed for 100V is going to fry at 135V. So over time, equipment vendors organized to try to force standards of conformity (the beginnings of NEMA). At first they settled on 117V +-10% as a compromise because the +- range works from 100-130V. If you look on 1920s vintage motorized devices in antique stores, you will often see them listed as 117V.

In the 30s, the REA (Rural Electrification Act) was enacted with the purpose of extending electrical service to farms and small towns, partly as a way to increase productivity. Because the REA administration did not want their work crews to have to carry multiple different transformer designs around in their trucks, they forced a settlement on 120/240V as the "DISTRIBUTION" voltage, meaning what the utility delivers, with 115/230V as the "UTILIZATION" voltage, meaning what the end device is designed for, acknowledging that there will be some voltage drop by the time it gets to the device. Later, those values were adopted by ANSI as the official standards. Those are the official standards to this day.

But still, the utilities that actually GENERATED AND DISTRIBUTED the voltage were not actually forced to change existing systems, they just had to used those standards for NEW systems. So to this day there are still pockets of legacy voltage levels in different places, which adds to the confusion all around. I don't personally know of any "110/220V" systems here in California, probably because the REA got here late. But I have been told they still exist.

As to 3 phase, it is 120/208, because 208 divided by the sq. rt. of 3, which is the phase to neutral voltage of a Wye transformer, is 120. Same for 480/277. Along the same lines of the residential voltage levels, there are older legacy systems for industrial use that are 440V, 450V, 460V, 550V and 600V, but officially it is now 480V dist., 460V util.
 

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Do you guys ever do 55v to ground 2 phase, giving 110 across phases?
You must be referring to the British power tool source.
They use a 230 volt primary, isolation transformer with a 110 volt, centered taped secondary, so each leg reads 55 volts to the grounded center tap.
I've read that arrangement is only used in large industrial or construction sites.
I've also read, that the British Isles, harmonized with the rest of the European continent at 230/400 volts. :rolleyes:
 

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History lesson:

"110V" is a legacy resulting from systems in the earliest days of electrification using AC distribution systems developed by Tesla for Westinhghouse. They had to compete with Edison, who was promoting DC for his electric lights, and through a series of experiments, he had settled on 100VDC as a compromised between safety and lumen output. So to make people willing to use AC, Westinghouse decided on 110VAC as a standard. I've read somewhere that he may have started out with 100VAC, but changed it to 110 because it sounded "better" than 100, kind of like the volume knob that goes to 11.

In the early days, once people started jumping all over the concept of long distance distribution of AC, there were different system voltages at almost every provider, ranging everywhere from 100-135V. That presented a challenge for equipment providers, especially those using motors, because a motor designed for 100V is going to fry at 135V. So over time, equipment vendors organized to try to force standards of conformity (the beginnings of NEMA). At first they settled on 117V +-10% as a compromise because the +- range works from 100-130V. If you look on 1920s vintage motorized devices in antique stores, you will often see them listed as 117V.

In the 30s, the REA (Rural Electrification Act) was enacted with the purpose of extending electrical service to farms and small towns, partly as a way to increase productivity. Because the REA administration did not want their work crews to have to carry multiple different transformer designs around in their trucks, they forced a settlement on 120/240V as the "DISTRIBUTION" voltage, meaning what the utility delivers, with 115/230V as the "UTILIZATION" voltage, meaning what the end device is designed for, acknowledging that there will be some voltage drop by the time it gets to the device. Later, those values were adopted by ANSI as the official standards. Those are the official standards to this day.

But still, the utilities that actually GENERATED AND DISTRIBUTED the voltage were not actually forced to change existing systems, they just had to used those standards for NEW systems. So to this day there are still pockets of legacy voltage levels in different places, which adds to the confusion all around. I don't personally know of any "110/220V" systems here in California, probably because the REA got here late. But I have been told they still exist.

As to 3 phase, it is 120/208, because 208 divided by the sq. rt. of 3, which is the phase to neutral voltage of a Wye transformer, is 120. Same for 480/277. Along the same lines of the residential voltage levels, there are older legacy systems for industrial use that are 440V, 450V, 460V, 550V and 600V, but officially it is now 480V dist., 460V util.
Holy crap. Thanks for the info!
 

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JRaef said:
History lesson: "110V" is a legacy resulting from systems in the earliest days of electrification using AC distribution systems developed by Tesla for Westinhghouse. They had to compete with Edison, who was promoting DC for his electric lights, and through a series of experiments, he had settled on 100VDC as a compromised between safety and lumen output. So to make people willing to use AC, Westinghouse decided on 110VAC as a standard. I've read somewhere that he may have started out with 100VAC, but changed it to 110 because it sounded "better" than 100, kind of like the volume knob that goes to 11. In the early days, once people started jumping all over the concept of long distance distribution of AC, there were different system voltages at almost every provider, ranging everywhere from 100-135V. That presented a challenge for equipment providers, especially those using motors, because a motor designed for 100V is going to fry at 135V. So over time, equipment vendors organized to try to force standards of conformity (the beginnings of NEMA). At first they settled on 117V +-10% as a compromise because the +- range works from 100-130V. If you look on 1920s vintage motorized devices in antique stores, you will often see them listed as 117V. In the 30s, the REA (Rural Electrification Act) was enacted with the purpose of extending electrical service to farms and small towns, partly as a way to increase productivity. Because the REA administration did not want their work crews to have to carry multiple different transformer designs around in their trucks, they forced a settlement on 120/240V as the "DISTRIBUTION" voltage, meaning what the utility delivers, with 115/230V as the "UTILIZATION" voltage, meaning what the end device is designed for, acknowledging that there will be some voltage drop by the time it gets to the device. Later, those values were adopted by ANSI as the official standards. Those are the official standards to this day. But still, the utilities that actually GENERATED AND DISTRIBUTED the voltage were not actually forced to change existing systems, they just had to used those standards for NEW systems. So to this day there are still pockets of legacy voltage levels in different places, which adds to the confusion all around. I don't personally know of any "110/220V" systems here in California, probably because the REA got here late. But I have been told they still exist. As to 3 phase, it is 120/208, because 208 divided by the sq. rt. of 3, which is the phase to neutral voltage of a Wye transformer, is 120. Same for 480/277. Along the same lines of the residential voltage levels, there are older legacy systems for industrial use that are 440V, 450V, 460V, 550V and 600V, but officially it is now 480V dist., 460V util.
Great info! I've often wondered the same thing.
The more you know....
Thanks
 

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Do you guys ever do 55v to ground 2 phase, giving 110 across phases?
Yup, in special applications like balanced audio power. However outside of audio installations its exceptionally rare. Our NEC requires one leg of 120 volts be grounded.

Do you guys ever use 115 to ground on both legs to give 230 volts or 133 volts 3 phase to give 230 volts between phases?
 
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