Electrical
Three-Phase Power
01 — Definition
A distribution scheme with three live conductors 120° out of phase, the norm for high-power AV distribution. The line-to-line voltage is √3 (about 1.73) times the line-to-neutral voltage: 400 V between phases for 230 V line-to-neutral in Europe, 208 V for 120 V in the US. Balancing the loads across the three phases keeps you from overloading the neutral and one phase while the others sit idle.
02 — In the field
Spread your fixtures and amps evenly across L1, L2 and L3. An unbalanced three-phase feed overloads one phase and its neutral while the other two loaf: a phase that trips mid-show is almost always a balancing failure.