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Thread: grounded delta

  1. #1
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    grounded delta

    Recently I came across a 480V 3-wire delta service with one leg grounded. An associate at Edison told me that 480V corner ground systems are illegal but 240V ones are not. This is the first time I have seen a 480V corner ground. I could not find anything on the code for it. Article 100, definitions mentions 480V 3-wire open grounded systems. What should we do with this service? And why would a 480V corner ground be legal when a 240V is not?

  2. #2
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    Re: grounded delta

    The NEC does not generally prohibit either installation. There may be a local amendment in your area. Look at art. 250 part II for specifics.

    It should be noted that there are occupancy limits for voltages (see 210.6) that may limit the 480V as well as the 240V corner grounded systems. Both would be nearly worthless in a residence, for example.

    Enjoy your day!

  3. #3
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    Re: grounded delta

    As scott has said this is only a requirment for a dwelling. but not for industral or comercial. Look at 210.6 Branch-Circuit Voltage Limitations.
    Wayne A. From: N.W.Indiana
    Be Fair, Be Safe
    Just don't be fairly safe

  4. #4
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    Re: grounded delta

    210.6(d) would prohibit a 480 volt corner grounded delta from supplying luminaires located inside of a building.

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