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I'm not sure if this is a case of selective memory, or if it's real.

It seems that Americans do not use the term "mains power," which is common in British English. The closest synonym I know is "wall power," which is imprecise.

As an American electrical engineer, I don't want to flip-flop dialects, and "wall power" is both naive-sounding and awkward when referring to 120V AC inside a device (but still coming from mains) or otherwise far from a wall.

Is there a better term I should know, or should I assume that "mains" is mainstream to my fellow Americans?

Edit: According to Wikipedia:

In the US, mains electric power (as opposed to battery electricity, etc.) is referred to by several names including "household power," "household electricity," "powerline," "domestic power," "wall power," "line power," "AC power," "city power," "street power," and "grid power."

This insinuates that "mains" is not a U.S. term, and that the alternatives are all equally imprecise.

Conclusion: Americans are likely to use "grid" as a synonym for "mains", which isn't baseless. So really the British style only seemed better because I hadn't yet considered whether the word already has another meaning.

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  • My conclusion: Americans are apt to think that you meant, dropped the main breaker. Instead of, just killed that one circuit.
    – Mazura
    Apr 8, 2015 at 3:53
  • That's funny. I would have unhesitatingly said "house current." I feel sure everyone used that expression when I was growing up. But apparently I'm wrong, because I can find not a single use of that sense anywhere.
    – Chaim
    Jun 8, 2018 at 16:45

7 Answers 7

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As another American EE, I would use "mains" only in certain contexts...

After the hurricane, the hospital powered life support equipment from diesel generators for 36 hours, then switched back to the mains.

"Grid" would also be acceptable.

If you're referring to 120VAC (RMS) without caring about source, the accepted U.S. industry-wide term is 'line voltage'.

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  • 4
    Line power, line level, line voltage is all I have heard in AE. To be more precise you could say 110V
    – mgb
    Apr 12, 2011 at 4:22
  • 1
    And line-cord for "mains lead" you can spend hours trying to explain to somebody in best-buy what you want!
    – mgb
    Apr 12, 2011 at 4:25
  • @mgb: Definitely power cord or extension cord (depending on the arrangement of receptacles at the female/socket end). Line cord sounds like it belongs up on a power pole with the transformers.
    – Ben Voigt
    Apr 12, 2011 at 4:28
  • A larger facility might receive its electrical power at a higher voltage, or in three phases instead of two. Grid power and line power include these. However, if the writer is talking about the power coming from a wall socket (single phase 120VAC) then wall power, regular outlet power or household current are all common. This distinguishes the regular outlet from the dryer outlet, which is wired for a higher voltage and current. Feb 13, 2021 at 21:12
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Wikipedia says:

In the US, electric power is referred to by several names including household power, household electricity, powerline, domestic power, wall power, line power, AC power, city power, street power, and grid power.

Which is indeed how I refer to household electricity. We never call it "mains power."

If someone began talking to me about the "mains," what I would think of is the power feed that comes into the breaker panel of the house (i.e. feeding the main circuit breaker), not the actual electrical outlets in the house.

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I don't know what's more common in daily speech, but I've heard AC power a lot, and you will often find that on American websites describing computer components and in manuals. I'd not be surprised to read line power or grid power in a technical manual either, but AC power might be more frequent in a technical context. But I'm not sure. If you need to be absolutely unambiguous, you could simply call it 120-V power or something like that.

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  • AC power is very suitable, unless there is another AC power source in the device. Grid power also works, unless the device interfaces with the actual grid side. I guess I just happen to be in a confusing position… Apr 12, 2011 at 0:07
  • @Potatoswatter: If it is important that you avoid ambiguity at all cost, you could name the power source by its voltage/current. Apr 12, 2011 at 0:29
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Haven't heard the phrase "mains power" here in America, ever in any context. I think "Wall power" refers to power that comes from "the wall" and "house current" refers to 120V/60Hz which may come from a generator etc. I don't think "wall power" can come from a generator.

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    Well… if the generator powers the wall outlets… Apr 11, 2011 at 23:58
  • 1
    I meant, "wall power" seems to require a wall, though "house current" doesn't seem to require a house.
    – bmcnett
    Apr 12, 2011 at 1:02
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I'm a telecom product manager in the US. I just watched a preso where another PLM used the term 'mains power'.
I assumed it meant 120VAC, but frankly I googled it to be sure...

Point is, I think 'mains' is not yet common enough in the US for even a relatively technical American to confidently know what you mean...

I suggest sticking with "120VAC" (and perhaps add 'or mains power' so as to continue socializing the term in the US : )

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  • What do you mean by socializing the term? I don't think the UK is a socialist country. ;)
    – JJJ
    Jun 8, 2018 at 16:10
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Definitely say AC power. And specify the voltage and the hz because in the United States power comes in two forms. In residences it's 120/220 (or in some areas 110/220) and generally 60hz. But in commercial applications it's often 130 volts. So be on the safe side and say exactly what you're talking about.

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I was trying to find a name easily understood by anyone. "The mains" is not anyways near a generalized term for what it is. Different Nations handle electricity (the mains) differently. But it's the same thing, it's electricity, just managed differently. I think "electrical power system" is a good term for how different nations handle electricity. Let "electrical power system" be representative of the numerous plugs, voltages, resistances, grounding and whatever may apply, to the individual way electricity is managed. Simple. Every nation or territory has its own "electrical power system" or systems, and anyone can easily grasp what "the mains" can't. The more simple, the easier to grasp and accept. My opinion.

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  • Please take a moment to tour the site and read the FAQ for how to answer with your research, not your opinion.
    – livresque
    Feb 14, 2021 at 1:27

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