Rockwell Automation 2100 CENTERLINE Low Voltage Motor Control Centers - Manual (Page 43)

Rockwell Automation Publication 2100-IN012E-EN-P - February 2012 43
Installing Conduit and Cable Chapter 3
Incoming Line Compartment
Top or bottom entry to the incoming line-section bus is straight through to the
connection terminals. The vertical bus provides pads for the incoming lugs. The
lug selection should be based on the size, number, and type of conductor.
• Use of mechanical screw-type lugs is acceptable only when the incoming
lines’ available short-circuit current is 42,000 A rms symmetrical or less.
• Use of crimp or compression type lugs is acceptable when the incoming
lines’ available short-circuit current does not exceed 100,000 A rms
symmetrical.
Main Disconnect
Top entry is straight through to the line side of the main fusible disconnect or
main circuit breaker. For bottom entry, the connection scheme varies depending
on the rating of the main device. In some cases, the bottom entry connects to the
top or line side of the main fusible disconnect or main circuit breaker. In other
cases the connection is reverse-fed, the bottom entry cables connect to the
bottom of the main fusible disconnect or main circuit breaker. For further
information refer to Mains and Incoming Lines Dimension Reference,
publication
2100-TD018 .
Mechanical screw-type lugs are supplied as standard with all main fusible
disconnects or main circuit breakers. Crimp or compression lugs are optional.
Cable Bracing
The CENTERLINE MCC bus work system has been tested and is qualified to
withstand maximum short-circuit forces exceeding the short-circuit withstand
ratings for the MCC. Incoming line cables and outgoing feeder cables also need
to be supported to withstand the same short-circuit forces. Follow NEC and local
codes when bracing incoming and outgoing cables. There are many sizes and
types of cables, as well as different means by which the cables can be supported.
Acceptable methods are shown on the following pages.