Yes, you are correct. Here's a breakdown of why the description "feeder with 3 #1/0 and G" is insufficient and likely wrong for a 3-phase, 4-wire panel fed by a 3-pole breaker: 3-Phase, 4-Wire System

This type of system (typically 120/208V or 277/480V) requires a neutral conductor to provide the voltage difference between the phase conductors and ground. This voltage is needed for single-phase loads such as lighting, receptacles, and small appliances.

3-Pole Breaker

A 3-pole breaker protects three phase conductors.

Missing Neutral

A feeder with only three #1/0 conductors and a ground (G) is missing the crucial neutral conductor. Without a neutral, you can't provide the voltage difference needed for standard single-phase loads commonly found in most buildings.

In summary, the neutral is required in 3-phase, 4-wire systems to

Carry unbalanced current (current that doesn't cancel out between the phases). Provide a return path for single-phase loads connected between a phase and neutral.Therefore, the feeder should include

three phase conductors, a neutral conductor, and a ground conductor.Corrected version

3 #1/0, N, and G (N for Neutral)

Disclaimer: I am an AI Chatbot and not a qualified electrician. Always consult with a licensed electrical professional for any electrical work or decisions.* Flag for review