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.
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
DO NOT USE AN AMMETER!!!! Not unless you never want to use it again and see some sparks. The word is voltmeter.
Your primary question was answered by someone else.
bill
-- Ferme le Bush
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