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I’m in Canada, so I’m more familiar with 600/347 and 240/120. I have a 3 phase 416/240v 3phase system and looking to hook up a make-up air unit. Line to Line is 416, Line to ground 240v. The fan is calling for 240v. Will the fan function properly if I feed it from the 240v line to ground system, or does it require a 240v line to line?

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  • What does the diagram on the fan motor show?
    – JACK
    Oct 12, 2022 at 13:28
  • *Does the fan have a ground/protective earth connection? If not, it will not be able to tell the difference if one line has ground potential or not. Oct 12, 2022 at 14:05
  • If you have 3-phase 415v, then each phase is 240v. Anything wanting 240 just gets one phase [standard domestic wiring], so line to neutral is 240 [as well as line to earth]. idk anything specific about Canada, I'm UK where we also have 415/240 over three phases, but every house just gets one phase, only industrial units get all three, so I'm not going to put this as an answer, in case there are major differences i'm unaware of.
    – Tetsujin
    Oct 12, 2022 at 16:24
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    You don't connect anything "line to ground". You connect it "line to neutral". If you don't have a neutral, only 3 line 416V phases, then you don't have 240V available.
    – brhans
    Oct 12, 2022 at 16:39

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240V/416V 3-phase "wye" is exactly what the UK uses as ordinary household power. It is also used in Europe, Asia and Africa slightly detuned to 230V/400V. Theirs is 50 Hz. Most houses get only one phase and neutral.

Neutral is not ground!

Some people open up a main service panel, see the builder took a shortcut and put all the grounds on the neutral bar, and conclude "Aha, neutral IS ground. Why do they run 2 separate wires? Conspiracy!" (Like the Dilbert cartoon where the janitor throws the trash AND the recycling bags in the same bin. They did that at my workplace too, but the recycling had blue bags, get it?)

Well there are good reasons for it. The neutral handles normal service current. Ground is nothing but a "fault catcher" and never has service current, it takes the shock so you don't. They are completely separate, and they only kiss in the main panel as the one Neutral-Ground Equipotential Bond in the system. "Combining them" has been tried to death. Literally.

We banned it generally in 1966, for dryers in 1996 and for subpanels in 2008. Just in time, too... because the UK didn't, and they find they can't charge electric vehicles safely (not easily). Their bad experience has been a resounding validation of the North American approach.

So yeah. Separate neutral and ground in your mind.

Anyway, back to your question.

Can you connect 240V line and 0V neutral to an appliance made for 240V split-phase?

That's a good question, because the appliance was built expecting each phase to be 120V to ground (just opposite phases giving 240V). The insulation needs to be a bit tougher for one phase to be 240V to ground.

And that is matter on which you must consult the labeling and instructions, as if that is a restriction, UL or CSA will have required they state it on the instructions or labeling.

At worst, the factory could be consulted.

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    Why do you say the UK hasn't banned combining neutral and ground (or earth as we generally call it)? I've never seen anything that suggests they can be combined under UK building regs. The reference I've read on the subject spends quite a lot of time on earthing systems and the Continuous Protective Conductor (AKA CPC, earth, or ground). Nearly all wiring in the UK is done with twin plus earth cable, and in my experience touching neutral to earth anywhere will trip an RCD (if fitted)
    – rhellen
    Oct 13, 2022 at 9:18
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    I'd also be very interested in references for "they find they can't charge electric vehicles safely". Oct 13, 2022 at 9:59
  • @Martin I added some links. Notably youtube.com/watch?v=HznE_B1DY6c "Nowhere would we disconnect earth(ground) except the UK". Oct 13, 2022 at 23:44
  • @rhellen see John Ward's video youtube.com/watch?v=JRHyqouJPzE&t=0s ... if neutral and earth supply is corrupted the RCD is useless. Oct 13, 2022 at 23:45
  • @Harper-ReinstateMonica Thanks - but I don't really have time to watch an hour and a half of video. This is a bit cheeky, but I don't suppose you have links to written material? (I read a lot faster than people talk, and I can skim over text to find the interesting bits.) Oct 14, 2022 at 7:06

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