The usual approach to solving unbalanced three-phase circuit problems is via the method of symmetrical components. This, ideally, requires a dedicated computer package. In the present contribution this is avoided by making use of a simple, but not well-known, electric-circuit theorem
due to Millman. Application of this theorem enables the voltage existing between the star-points of, say, a generator/load combination to be easily established. Once this voltage is known, the rest of the circuit variables can be calculated in the usual straightforward manner. Examples of
this method's use in various unbalanced (including fault) conditions are illustrated. It is hoped that this simple technique will be particularly convenient for check calculations in the field, for it requires no other aid than a hand-held calculator.