Anyone know why voltage 120/240 is referred to as 110/220

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ritelec

Senior Member
Location
Jersey
Hey all and Merry Christmas....

Why do some refer to 120/240 volt as 110/220.......??

Is there any technical reason to it??

Thank you
 

kwired

Electron manager
Location
NE Nebraska
At one time those were "nominal" voltages. Today 120 and 240 are the nominal voltages. You also find some that still use the term "440" for 480 volt systems.

I can not give you details on when and why the changes occurred.
 

junkhound

Senior Member
Location
Renton, WA
Occupation
EE, power electronics specialty
Merry CHRISTMAS

1880s Edison's dc distribution was 110Vdc, earliest ac the same voltage so lamps were compatible.

Nov 14, 2007 (yes, 2007, that 'late') was when the last 110 Vdc distribution was disconnected in New York City. NYC started converting to ac in mid 1920s.
A co-worker once mentioned that when he went to college in Boston in the early 1960's, his small radio burnt out when he tried it in his new apartment - some parts of Boston still had 110Vdc distribution then.

I have a fuse box from 1914 labeled 15A 110V used in Illinois, so at least to that time 110V was the standard, and in places, up to 2007<G>.

Have some old radios circa 1950 labeled 115Vac.

Have and old Sioux 1/2" drill circa late 1940's labeled 110V.

Mid 1960's Craftsman power tools labeled 110-120V AC-DC, so still in transition at that time.

And of course, the 'all American 5' tube radios sold into the early 1970's (ac-dc; 100 - 120V) Don't think the tube life was too great at much over 120V?

Many modern solid state 'wall warts' labeled 100-240V, but of course the power electronics are different now than the 1960s.
 

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
PE (Retired) - Power Systems

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
ANSI C84 is the industry standard that covers our nominal voltages. 120, 208, 240, 480, 600V have been the standard for more than 50 years.
Read the forward for a little history.
http://www.nema.org/Standards/ComplimentaryDocuments/Contents-and-Scope-ANSI-C84-1-2011.pdf

Terms like 110 and 115V are left over from the oldtimers that used to mentor us. We have kept the bad habits alive.

I cringe almost daily at the 110 volt terminology being used by electricians both young and old, even when the system is 208Y/120. :slaphead:
 

Besoeker

Senior Member
Location
UK
I cringe almost daily at the 110 volt terminology being used by electricians both young and old, even when the system is 208Y/120. :slaphead:
I've previously commented The complexity of the different voltages.
I can sort of understand where the 120-0-120 comes from. Ignoring the earthing, it is a three wire system. Balance the 120V loads and the current in the neutral conductor is minimised.
But if everything, lighting and domestic appliances were rated for 240V it would be a two wire system wouldn't that greatly simplify installation?
And wouldn't it remove, at a stroke, the seemingly ubiquitous problem of lost neutrals causing conflagrations and consternation?
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
We build load banks for nominal 200/115V Y systems. Of course they are 400 Hz.

I think there are some things that are not quite right but just won't go away.

OTOH, a lot of three phase motors say 460V on them.
 

iceworm

Curmudgeon still using printed IEEE Color Books
Location
North of the 65 parallel
Occupation
EE (Field - as little design as possible)
I cringe almost daily at the 110 volt terminology being used by electricians both young and old, even when the system is 208Y/120. :slaphead:
Yes. Really sounds sloppy to me. Unless it is a movie line being quoted - "220, 221, whatever it takes"

This is right up there with, " xx Amps per phase".:sick: Or adding the three phase currents together. "3C - 4/0 is good for 690A) :sick::sick:


ice
 

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
PE (Retired) - Power Systems
OTOH, a lot of three phase motors say 460V on them.

Motors and most other 'loads' are usually labeled with utilization voltage which is about 4.2% below nominal (e.g. 115, 230, 460, and 575)
Connector type equipment (e.g. plug or screw thread) are usually labeled with a maximum nominal which is about 4.2% above nominal (e.g. 125 and 250).

The NEC says we should be using nominal levels when we mention voltages. (e.g. 100 definitions, 110.4, and 220.5(A)). Therefore strictly speaking, saying 110V violates the NEC.:eek:hmy:
 

kwired

Electron manager
Location
NE Nebraska
OTOH, a lot of three phase motors say 460V on them.

Motors and most other 'loads' are usually labeled with utilization voltage which is about 4.2% below nominal (e.g. 115, 230, 460, and 575)
Connector type equipment (e.g. plug or screw thread) are usually labeled with a maximum nominal which is about 4.2% above nominal (e.g. 125 and 250).

The NEC says we should be using nominal levels when we mention voltages. (e.g. 100 definitions, 110.4, and 220.5(A)). Therefore strictly speaking, saying 110V violates the NEC.:eek:hmy:

To add to what Jim mentioned, all the other data on that nameplate should be accurate if the voltage is 460 and full load is applied. If it is marked with efficiency, power factor etc. the nameplate values will all be accurate when voltage and current match the nameplate rating.

I think part of the reason they rate them at the voltages Jim mentioned is that it allows for some voltage drop from nominal and this will still get the actual values near the nameplate values.
 

iceworm

Curmudgeon still using printed IEEE Color Books
Location
North of the 65 parallel
Occupation
EE (Field - as little design as possible)
... I think part of the reason they rate them at the voltages Jim mentioned is that it allows for some voltage drop from nominal and this will still get the actual values near the nameplate values.
That's the only reason. 460V gives a Vd from the nominal system 480V - Which is normal at the end of the feeder.

In the 1960s the motor nameplates were 440V. System voltage was 440V. Motors probably got about 422V - about 4%low. Motors had to run in the SF to get rated power.

I recall a lot of people lamenting the bygone days of U-frame motors and speak unkindly of the cheap T-frame. Yes, the U-frames had a lot more steel and copper than the newer T-frames. But the T-frame has a lot better steel, better insulation, better winding techniques, wound closer to the expected voltage, better efficiency, lower power factor. Makes one wonder what exactly was better.

(Normal Answer) Well they weigh more, they have to be better.

Spoken like a true aficionado of "110, 220, 440", but not "220, 221, what ever it takes":roll:

JAO

ice
 

kwired

Electron manager
Location
NE Nebraska
That's the only reason. 460V gives a Vd from the nominal system 480V - Which is normal at the end of the feeder.
Could be, but most places around here with 480 volt nominal service generally run around 495-500 volts at the supply end, and unless you have a pretty significant voltage drop are still above 480 at the motor. And 240 volt services generally run 246-250, 208 volt services typically about 215 - 218 volts.
 

mbrooke

Batteries Included
Location
United States
Occupation
Technician
I've previously commented The complexity of the different voltages.
I can sort of understand where the 120-0-120 comes from. Ignoring the earthing, it is a three wire system. Balance the 120V loads and the current in the neutral conductor is minimised.
But if everything, lighting and domestic appliances were rated for 240V it would be a two wire system wouldn't that greatly simplify installation?
And wouldn't it remove, at a stroke, the seemingly ubiquitous problem of lost neutrals causing conflagrations and consternation?

Ever since I started I have always wondered why everything wasn't straight 240 volts. It never made any sense considering most other parts of the world have low cost 240 volt appliances. Still blows me away, especially considering how much people screw up the neutral here or just don't get it. 240 could also give rise to 240/415Y in commercial. In my opinion north America has one of the worst systems from an efficiency stand point because buildings often have 2 voltages. 277/480 or in Canada 347/600. The higher voltages feed 480 volt motors and 277 volt lighting. Its step down in buildings to 120/208 for everything else that needs it. Hence buildings need double the breaker panels, way more wire/materials and space is taken up. Add to the fact most of the transformers run 24/7 places like office buildings have them humming away giving off several hundred watts of heat even though nothing is drawing power.

Habits and rituals don't change I guess.
 

ritelec

Senior Member
Location
Jersey
Ever since I started I have always wondered why everything wasn't straight 240 volts. It never made any sense considering most other parts of the world have low cost 240 volt appliances. Still blows me away, especially considering how much people screw up the neutral here or just don't get it.

???

Do I hear 480 !!!

Shoot..............lets go for 2000v "nominal"................
 
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chris kennedy

Senior Member
Location
Miami Fla.
Occupation
60 yr old tool twisting electrician
I've previously commented The complexity of the different voltages.

I got CO yesterday on a 27,000ft? facility that makes boxes. I have AC supply voltages to equipment consisting of;

120
208
229
236
380
400
470
480

Thought about adding a 277V luminaire next to my gear just so I could say I have 277 also.;)
 

junkhound

Senior Member
Location
Renton, WA
Occupation
EE, power electronics specialty
Habits and rituals don't change I guess.

For one, own preference to maintain 120 is that it is 'comfortable' to test for a live circuits at 120 V with dry fingers, while testing 240V with my fingers is a little uncomfortable, and 277 downright painful. Plus, when you change out an outlet live and the screwdriver slips, there is less of a gouge cut into your screwdriver at 110 or 120.

OSHA be damned, full speed ahead, too far to the truck to get the meter and too far to go to flip the breaker <G>
 

PetrosA

Senior Member
I could see the sense in moving to a 240V system in homes, but it would be even harder to change to than converting the country to metric (which would actually be pretty easy). It would make trillions of dollars worth of equipment obsolete overnight. It would certainly make 200A services in residential seem very strange. Based on wire gauge, our 15A circuits would become 16A, 3kW circuits (based on international standards) and 20A circuits would become 25A 6kW circuits - as much as many apartments have around Europe...

On the plus side, it would certainly act as a deterrent to working live. ;)
 
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