NEMA Class 1 (motor control centers)

Independent units consisting of mechanical
groupings of combination motor control units,
feeder taps, and electrical devices arranged for
convenient assembly. Wiring is complete
between components within each unit.
Connections between units are not provided.
NEMA Class 2 (motor control centers)
Interconnected units consisting of mechanical
groupings of combination motor control units,
feeder taps, and electrical devices arranged for
convenient assembly. Electrical interlocking and
wiring between units is provided. These
interconnections are completed as called out by
the purchaser.