Single-phase pole or overhead-type transformers can be used to obtain three-phase secondary service.

• A. Yes
• B. No
• C. Only with transformer banks
• D. Only at certain configurations

Answer: (A)

Three-phase secondary service can be created by combining multiple single-phase transformers into a 3-phase bank. By wiring three single-phase overhead transformers in a proper three-phase configuration (delta or wye) you obtain the three distinct phase voltages needed for a three-phase service. There are also arrangements using two transformers in open-delta to supply a 3-phase load, though that setup doesn’t carry full capacity like a full three-transformer bank. So, it is indeed possible to derive three-phase service from single-phase overhead transformers, which is why the correct conclusion is Yes.