Final answer:
A service entrance with three connected conductors is a phase 3 supply.
Step-by-step explanation:
A service entrance with three connected conductors is a phase 3 supply. In electrical systems, a three-phase supply refers to a system that uses three hot wires, also known as live wires, to provide power. These hot wires are usually labeled as L1, L2, and L3 and are typically connected in a wye or delta configuration.