Publication 2100-IN012B-EN-P - April 2005
Installing Conduit and Cable 4-3
1. Use of mechanical screw type lugs is only acceptable when the incoming
lines available short circuit current is 42,000 amperes RMS symmetrical
or less.
2. Use of crimp or compression type lugs is acceptable when the incoming
lines available short circuit current does not exceed 100,000 amperes
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 publication 2100–4.2, Mains and Incoming Lines
Dimension Reference.
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 in Figure 4.1,
Figure 4.2 and Figure 4.3.
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