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3 Phase Power Question

I was wondering if someone could explain this to me. I'm not an electrician, but am curious as to how this would work. I have 3 phase power coming into a disconnect box. Basically 5 wires (Ground, Neutral, L1, L2 and L3). I am going to have a battery backup system connected to this box. The backup system has a 3 wire input labeled Ground, L1, and the third connector is labeled either L2 or Neutral. The input is rated at 208v to 240v. If I connect a Ground, L1 and Neutral to the system, will that not be a 110v connection? Again, not an electrician, just trying to satisfy my curiosity.

Reply to
rclark
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Depends what type of 3 pahse system you have. Is it delta or wye? Is it 240/208 or is it 480? If you have a good VOM, check the AC volts from L1 or L2 or L3 to the neutral. This should answer your question. Sounds like you have 240/208 wye system, since it has a neutral. Two of the "hot legs" should give you 120 VAC to the neutral. One of the legs may be a lot higher. You really need to check the voltages with a good meter rated for at least

600 Volts.
Reply to
Skenny

So you are saying that I could possibly read 208/240 from one of the 3 legs to Neutral?

Thanks,

Skenny wrote:

Reply to
rclark

Check out this site, maybe it will help you to see a picture of the transformer wiring:

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like I said, I would use a volt meter first. If the device you are connecting is 208/240, you can probably connect it between two of the hots. (L1-L2 or L1-L3 or L2-L3). But there may be a jumper or switch on the device that you have to set for either 208 or 240. Again, a meter on the lines will tell you which to use. Hope this helps.

Reply to
Skenny

Reply to
rclark

Don't do it. At least not without the assistance of a good electrician or decent engineer.

Just matching up the nomenclature on the wires is no guarantee that you are going to be feeding your loads without risking damage to them, the backup system, or both.

Reply to
Paul Hovnanian P.E.

Reply to
Skenny

Reply to
rclark

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