# 3 Phase Vs. Split Phase Test ??

Can anyone advise a method of determining whether the two phases in an electrical box is a split phase (180 deg. offset) or is it 2 phases of
a 3 phase transformer (120 deg. offset) I was told this can be done with an ammeter.
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If all you have is two wires, its single phase. It may have come from split, or a 3-phase setup, but all you can get with two wires is single phase period.
Now, if you have *three* wires, measure the voltage between each combination. If one combination is exactly double the others, then you have a 'split' or 'Edison' connection (like a typical US residential service). (for example 120-120-240)
If the voltage of one combination is 1.73 times the others, you have the neutral and two legs of a three-phase wye. (for example, 120-120-208).
If the voltage is exactly the same each way, you have three-phase with no neutral. Could come from a wye, or delta feed.
daestrom
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On 7/2/06 12:44 AM, in article snipped-for-privacy@v61g2000cwv.googlegroups.com, " snipped-for-privacy@optonline.net"

DO NOT USE AN AMMETER!!!! Not unless you never want to use it again and see some sparks. The word is voltmeter.