Publication 2100-IN012C-EN-P - April 2009 43
Installing Conduit and Cable Chapter 3
3. Use the MCC electrical schematics to verify field wiring
connection points.
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.
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