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My goal is to have a house where all loads are powered by 240V, that is fully livable in all the normal ways. And this question concerns the hard, in-house, built-in wiring; we will armwave the availability of plug-in appliances.

Under NEC 2014/17, will it be possible to a) serve all built-in (ordinarily hardwired) loads with 240V supply?

I am willing to switch appliances (e.g. to all hard-wired lamps, and to all socketless, light emitting or discharge lights). There won't be a conventional forced-air furnace; it'll be mini-splits, baseboard emergency heat, and electricityless Empire heaters.

Let us presume I have either found US-legal 240V plug-in appliances, or decided to do without them.


Code calls out a number of 120V circuits and receptacles that specifically must exist: kitchen counter receps within 2' of any point on a countertop, wall outlets within 6' of any point along a wall, laundry room, bathroom, outdoor etc. I'm willing to physically install them as well and just leave them de-energized. With 240V circuits right next to them. 120/240V multi-wire branch circuits will not be used.

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  • 13
    What country are you in? To answer for my country (UK), all houses are fully 240V.(Note that official tables will state 230V, but that's because a while back we agreed to synchronise with the rest of Europe at 220V, but call it "230V plus or minus 10%". So while it's CALLED 230V, we still actually have 240V!) Aug 13 '20 at 9:33
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    @ChrisMelville Actually, Europe is also at "230 V ± 23 V". The difference between mainland Europe and the UK existed until 1987 when they started to align the network voltage. Most of Europe was on 220 ± 22 and the UK had 240 ± 24 (that's the 10% you mentioned). Since the ranges overlapped they decided to meet in the middle with little need for adaptation in most appliances.
    – YetiCGN
    Aug 13 '20 at 10:50
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    @YetiCGN - Absolutely right. That's just the flip-side of my comment. The UK still has 240V, and the Continent still has 220V. But we all just decided to call it 230V with a 10% margin of error :) Aug 13 '20 at 10:58
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    Good luck selling the place when you wish to move out...
    – MonkeyZeus
    Aug 13 '20 at 11:26
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    P.S., ...extension cords stapled to walls and baseboards, painted over, hidden under rugs, I don't know what all else; but everything I said above is something that I actually have seen at one time or another—especially in rental units in neighborhoods that are heavily infested by college undergrads. Aug 13 '20 at 19:19
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Such a fun question deserves an equally fun answer.

Sure you can! And there's a neat trick that will help with all those troublesome NEC 2014/17 rules: simply make sure to build this house in a country where the NEC does not apply!

Most of the world uses 230V as their standard supply voltage, which is pretty close, but if that's not quite enough for you, there are 19 countries that use exactly 240V by default, and would make an ideal location to build a 240V-only house.

  • Brunei
  • Cook Islands
  • Cyprus
  • Falkland Islands
  • Fiji
  • Gibraltar
  • Isle of Man
  • Kenya
  • Kiribati
  • Kuwait
  • Libya
  • Nauru
  • Oman
  • Papua New Guinea
  • Qatar
  • St Lucia
  • Seychelles
  • Tonga
  • Uganda

(source: https://en.wikipedia.org/wiki/Mains_electricity_by_country)

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Several have mentioned The required 120v circuits include 2 small appliances for kitchen counters, 1 for the laundry, 1 for the bathroom(s).

But I think the main problem you run into is 210.6.

210.6 Branch-Circuit Voltage Limitations. The nominal voltage of branch circuits shall not exceed the values permitted by 210.6(A) through (E).
(A) Occupancy Limitation. In dwelling units and guest rooms or guest suites of hotels, motels, and similar occupancies, the voltage shall not exceed 120 volts, nominal, between conductors that supply the terminals of the following: (1) Luminaires
(2) Cord-and-plug-connected loads 1440 volt-amperes, nominal, or less than 1∕4 hp

This limits the voltage to 120v nominal between conductors for luminaries and cord and plug connected loads 1440 nominal or less. This means all those 240V devices other countries use would not be code compliant in the US with regard to lighting and appliances as most are under 1500W.

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  • So if I have 240V receptacles in a garage workshop for tools, with no neutral in that box, I can't run some lighting fixtures on the same circuit? Aug 12 '20 at 19:24
  • @manassehkatz-Moving2Codidact there are provisions in 210.6(C) which allow luminaires on 277V circuits.
    – brhans
    Aug 12 '20 at 19:29
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    If I understand electricallicenserenewal.com/… correctly, it sounds like with the 2020 code, cord-and-plug-connected or permanently connected utilization equipment are permitted too. Which means that the only real limits of "120V only" (aside from required for kitchen, etc.) is the smaller sizes of Edison bulbs - which makes sense because you don't want to have a 240V light bulb socket where an unsuspecting user could screw in a standard 120V bulb. Aug 12 '20 at 19:35
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    @JACK, most of Europe uses 230V phase-to-ground and 400V phase-to-phase.
    – Nate S.
    Aug 12 '20 at 22:51
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    For what it's worth, I would parse that as "in (dwelling units) and (guest rooms or guest suites of hotels)" but I agree it's ambiguous. Could indeed be parsed as "in (dwelling units and guest rooms or guest suites) of hotels" as well, or even "in (dwelling units and guest rooms) or (guest suites of hotels)". Would've been better if they listed it differently.
    – SQB
    Aug 13 '20 at 12:19
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Pointless exercise. The "armwave" of the existence of all possible loads being available in 240V is not insignificant. Most major appliances are already 240V, so you are only referring to things like lighting, small appliances, entertainment, personal items, PCs etc. Yes, you could buy them from overseas in 230V versions, but you would then have to change the plugs to match legal 240V plugs available here or buy adapters and why on earth would you want to go through that hassle? There is NO ADVANTAGE to using 240V for small loads.

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