My question: I'm replacing a metal halide fixture with a LED fixture. The outlet is single phase 240V (split with no neutral). Is it ok to connect the LED fixture to this outlet? I'm asking because the voltage range on the fixture is 100V to 277V, but I'm not sure if the voltage has to be on a single wire with neutral or if it is ok to be split.

Thanks in advance.

  • Knowing the model of the light would be helpful. The lights that I have installed have a line and neutral , with some of these lights they can be used on 240 split phase BUT some cannot. We need to check the type and schematic or listing info to know for sure. – Ed Beal Jun 14 '19 at 16:41
  • Its a UFO high bay light. Bought on Amazon. The model is HERO Series. The diagram just shows the line and neutral wires of the fixture and the range of the voltage. It doesn't mention if it can be split voltage or not. I have a few units I have to install. I already plugged one in and it works. I just want to make it doesn't mess up the driver later on. – Paul Jun 14 '19 at 16:54
  • @Paul Amazon Marketplace trash is not UL listed, but technically luminaries are not required to be. psst... despite my railing against that junk in installed mains equipment which must be listed, I do use Cheese cheapie luminaries. – Harper - Reinstate Monica Jun 14 '19 at 17:35
  • Harper, these units are UL listed. They are inexpensive, but so far the ones I installed about 6 months ago have been working with no issue. (different location) – Paul Jun 14 '19 at 17:50
  • is there a labeled neutral terminal? – Jasen Jun 14 '19 at 21:46

Below is based on US 120V/240V system:

An ordinary device (not talking about a tester that has access to hot/neutral/ground) can't actually tell the difference between hot/hot vs. hot/neutral. There is no polarity in AC as there is in DC. From a practical standpoint, it comes down to voltage requirements:

  • 120V (nominal) = hot/neutral
  • 240V (nominal) = hot/hot

So for a device that can use the entire range 120V to 240V (e.g., 100V - 277V), either one will work just fine. The exceptions come in three flavors:

  • 120V only = Devices that don't need very much power and designed specifically for 120V and not much higher than that.
  • 240V only = Devices that need more power and designed specifically for 240V and not much lower than that. Typically these devices actually would work safely at 120V but not produce the desired output (e.g., a 240V dryer at 120V will only produce 1/4 the heat and take 4x as long to dry clothes).
  • Combination devices. Typically this includes dryers and ovens - 120V for controls and lights, 240V for heat. Depending on design, they may not work at all with only hot/neutral or work but not produce the expected amount of heat. Depending on design, they may not work at all with only hot/hot or work but with limited features.

Bottom line: If the device (light fixture but sometimes other things such as computer power supplies) only uses two wires (plus ground, of course) and has flexible voltage (from <= 120V to at >= 240V) then you can connect it to two hots instead of hot + neutral.

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    Not always true, some of the imports have the neutral attached to the case or grounded, putting a hot on the N line can be hazardous. – Ed Beal Jun 14 '19 at 17:07
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    Probably talking about something like this. How the ground and neutral interact and if they are attached to the outside case are the important considerations. Ground should be attached to the housing, and neutral should not touch ground, but that would have to be tested. – JPhi1618 Jun 14 '19 at 17:14
  • @JPhi1618 Good point about ground. If everything is designed correctly on a modern fixture (and all LED fixtures certainly), the case should only be connected to ground and not to either of the regular wires. But older fixtures often had case == neutral and in such a situation if ground & neutral were not the same then there would be a problem. Easy enough to test - make sure continuity between case & ground, no continuity between case and any other wires (or between any other wires & ground). – manassehkatz-Reinstate Monica Jun 14 '19 at 17:34
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    Yea, just find a spot on the case with no paint. Screw holes usually work good, but even then can have paint in them. – JPhi1618 Jun 14 '19 at 17:35
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    Thanks everyone for the input and help. I didn't think the neutral was attached to ground, otherwise the one I have mounted and plugged in would have tripped the breaker. I did just finished checking continuity on another one and only ground has connection to the frame. – Paul Jun 14 '19 at 17:55

Easy peasy, just hook it up to hot and hot. Doesn't matter which.

You are relying on the device having competent neutral-ground insulation, but it should, because if it did not, it would fail in any of these applications:

  • many European countries use Schuko or other reversible plugs.
  • GFCI cares about neutral-ground insulation
  • Philippine power works exactly like what you are doing

By the way if you plug it in use NEMA 6 plugs and sockets, never NEMA 5.

If one of the wires is white or light blue, that goes to a hot. Tape it with black tape to mark it as a hot in this installation, so the next maintainer is not confused.

This type of device auto-ranges between 100V and 277V using switching power supply technology, same as most cell phone chargers and laptop power supplies. 100V is Japanese appliance power. 277V is American power in large institutions; it is one leg of 480V 3-phase "wye". It will also play nice with American 120V, Brazil 127V and 220V, NYC 208V, Africa 220, EU 230, UK 240 etc.

  • Thanks Harper. My confusion was not how to wire it, my confusion was being it is a cheap chinese product I wasn't sure if the voltage range had to be supplied from one wire only with the other wire strictly neutral, or if it could both be hot. I apologize my question didn't come thru correctly. Again thanks to everyone for your help. – Paul Jun 14 '19 at 19:53
  • @Paul That is a very good question, but Philippine power works exactly like you are doing, so I would think they would caution not to sell it in Philippines if not. – Harper - Reinstate Monica Jun 14 '19 at 19:55

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