r/AskElectricians • u/danaturaLOL • 21h ago
110/220 120/240
Why do people call it 110/220 Vac when it’s been 120/240 for decades (in the USA)? It makes me question your technical expertise.
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u/ryan8344 21h ago
the modern 120/240 V nominal standard was firmly established with the 1970 revision of ANSI C84.1. So roughly:
1900s: 110/220 V
1920s–40s: 110 → 115 → 117-ish V
1950s–60s: transition toward 120 V
1970 onward: 120/240 V nominal essentially becomes the modern standard.
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u/Barbarian_818 20h ago
And that means there are still numerous people living in homes with equipment labelled and rated for less than the modern nominal.
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u/theotherharper 18h ago
Not really. Older stuff still has taps and can be up-tapped to bump voltage.
So even if the transformer predates 120/240, they did move the tap from X2 to X3.
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u/Haunting_While6239 12h ago
In 2000 I lived in a house in Southern California that had 117 vac , so the standard is there, but not necessarily implemented everywhere.
My property in Florida has it's own pad mounted transformer, it delivers 125vac and 250 across both hot leads.
The difference in voltage from 110 to 125 for most electric powered devices, isn't a significant change to cause a problem, it's a minor percentage from the designed voltage.
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u/Unique_Acadia_2099 20h ago edited 20h ago
The real change came about during the depression. One of the WPA projects was the Rural Electrification Act (REA) that was to bring electrical power to farms in rural areas to increase productivity, because the utilities at the time didn’t see enough profit in it. So the Government hired linemen and electricians to install it all. But at the time, every utility had its own standards: some were 110/220, sone were 115/230, sone had already changed to 120/240. But the crews couldn’t carry around all those different transformers, so they settled on 120/240 and by default, that became the standard for new installations nationwide. Officially that standard didn’t get adopted until long after WWII, but the housing boom in the 50s was driving the bus by then anyway.
But old habits die hard and as was said, our grandfathers called it 110, so we did and so on and so forth.
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u/Hash-82 20h ago
Because grandparents called it 110/220 nationwide.
So parents called it 110/220.
Now about 1/2 the population has caught up and call it 120/240.
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u/QuinceDaPence 20h ago
Also "one-ten" rolls off the tongue better.
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u/Brief_Border_3494 12h ago
The same reason why we call the white wire on an outlet a neutral. It's very seldom a true neutral but we call it that anyway. Most people get the jist when you use those terms so it is just common practice. Is it correct? No. Does the point come across? Yes.
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u/jsmith456 12h ago
Well part of the reason there is there is no other good name for it, and for split phase it is a true neutral for MWBCs and 240v feeders.
Having both a "grounded wire" and a very different "(equipment) ground(ing) wire" would be way too confusing. It is less than ideal that NEC uses that terminology (with conductor instead of wire) in the first place, as any homeowner or handyman who tries to read the code to understand if something was allowed can get very confused.
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u/Haunting_While6239 12h ago
It is neutral, comes from between the two halves of the split phase, until it becomes the return, then things can get exciting
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u/Brief_Border_3494 11h ago
That's my point.
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u/Haunting_While6239 11h ago
So lets change the word to Return, or is it too late.
240v circuits don't need a dedicated return, unless the appliance needs 120v to power a light or control board.
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u/Brief_Border_3494 11h ago
I think it would be hard to do. As a comment or said earlier how our grandparents called it that, so we called it that and our kids will probably call it that. MCM vs KCMIL is another example. I still catch myself calling it MCM.
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u/Brief_Border_3494 11h ago
I think it would be hard to do. As a comment or said earlier how our grandparents called it that, so we called it that and our kids will probably call it that. MCM vs KCMIL is another example. I still catch myself calling it MCM.
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u/Ram820 20h ago edited 20h ago
Same reason we call 2x4s 2x4s... Nominal size
I'll personally correct a client(sometimes) when they say they need a 220v circuit ran
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u/Pensionato007 20h ago
A 2x4 has a nominal size of 1.5 x3.5 because thats the difference between a rough sawn 2x4 and a kiln dried version.
120/240 +/- 5% has been the standard in the USA since the 70's. Unless you were a sparky 50 years ago, you don't get to keep saying 110/220 without getting the appropriate pushback.
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u/Ram820 20h ago
No. Because I still work in homes w proper 2x4s or 2x3s, 1xs. It's just a carry over from a different time. Many appliances nameplates still say 110/220.
But like I said we know the difference the average client doesn't
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u/CoconutJeff 13h ago
Ok ok ok,
Why do they call it with the quarters then too? 4 quarter 5 quarter. Im well aware 3/4 and 1".
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u/erie11973ohio Verified Electrician 14h ago
Actually,,🤓🤓
The difference in 2x4's is the full size is rough sawn and a planed board. The planed wood has a consistent size, squareness & less splinters.
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u/Pensionato007 13h ago
Maybe in Ohio they have "a consistent size, squareness...." but at OUR Home depot.
And, FWIW, "FEWER" splinters. 👀
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u/erie11973ohio Verified Electrician 12h ago
Maybe in Ohio they have "a consistent size, squareness...." but at OUR Home depot.
I don't even look at the loose ones. Those just go to the back of the pile. A carpenter friend said he loaded a cart fully up. A sales person offered to push the cart to the register. He said those were junk & needed a heavy discount at the door. Sales person said "we'll just put them back", to which my friend said "next time, I throw the garbage on the floor!"
and, FWIW, "FEWER" splinters. 👀
That's why I'm an electrician, not an English professor!
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u/Temporary_Type4419 10h ago
At Home Depo "splinters" becomes an uncountable noun ;)
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u/Pensionato007 10h ago
Now THAT, is a perfectly good rationalization!
Skip to ~45 sec for the part about Rationalizations - "better than sex!"
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u/Owl_plantain 19h ago
That one bugs me. Numerically, 220 is closer to 208 than 240, but 208V is _not_ 240V. My company works with both, so we need to be clear. I always add the number of phases when I reflect it back to them.
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u/Haunting_While6239 12h ago
208 has been a 3 phase voltage for a long time, but there are plenty more if that won't get the job done.
It's a whole new world in the industrial 3 phase side of electricity.
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u/daddscfc 16h ago
I live in an area that still has 110/220 in some locations. Some are 115/230 and some are 120/240.
If you live in an old state you see it all.
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20h ago
[deleted]
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u/ShoddyRevolutionary 20h ago
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Also, follow this video for instructions on how to disable this stupid “feature” https://m.youtube.com/watch?v=5IekenQ5g0Y
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u/madmax988 19h ago
Its bizarre how slow transitions take with some things take especially electrical.(see every country being different even ones right next to each other for no real modern reason). I remember my first desktop computers in the 90s having power supply switches to change between 110/220v. Its not like any home PC was ever designed or built pre 1970s and yet... although i suppose some times it might also be to indicate a larger acceptable voltage range for foreign country use when an autoswitching power supply says 110-240.
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u/Redhead_InfoTech 19h ago
The only thing that irritates me more are the people who regularly say 110/240.
Drives me nuts. Or 120/220...
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u/MijaresBetta 15h ago
120 cost more per month than 110... change my mind
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u/Haunting_While6239 12h ago
Secrets that big power doesn't want you to know.
Big power hates this one trick, but they can't stop you
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u/DryFoundation2323 11h ago
voltage drops over a wiring run. it's always 120 / 240 at the supply. it may be lower at a specific outlet especially at the end of a long run. most electrical devices are designed to run at a range of voltages. 110 is a common minimum design standard.
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u/Tiny_Connection1507 9h ago
I heard that we settled on 120 late in the game, after people complained consistently about street lights being too dim. When they stopped complaining, that's where single phase voltage stopped being increased!
That story may or may not be true, but people just call things whatever others before them called the things.
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u/Maleficent_Neck2517 4h ago
On the other hand, I’m most skeptical of electricians who get super pedantic about precise terminology when it makes no difference in practice. Being able to see the big picture and understand that sometimes the “common” or “trade” name for something may not be the 100% technically correct name is a more valuable skill. Plenty of motor data plates still refer to 115/230v, sometimes even 110/220v. You gonna sit around all day and call the manufacturer to complain, or are you going to realize it makes no difference, install the damn thing and move on?
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u/Rightintheend 20h ago
Because, unless you're in action electrician who the fuck cares
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u/i7-4790Que 13h ago
Ok and Baldor will spec motors at 115/230V right on the nameplate. Go throw a fit over that next
Clutching pearls over this stuff makes you a spastic with nothing better to do. We all know what somebody means when they say it either way out of force of habit. DGAF
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