63
Instructional Leaflet
IB2C12063H03
Effective March 2012
Instructions for Installation, Operation and
Maintenance of Magnum SB Insulated Case
Low Voltage Power Circuit Breakers
EATON CORPORATION
www.eaton.com
The contact wear indicator is the relative position of the indi-
vidual contact fingers to a narrow, side-to-side ledge inside
the arc chamber . The ledge is actually part of the arc chamber .
When the circuit breaker is closed and the contacts are in good
condition, the narrow ledge is covered by the back end of the
contacts (
Figure 93
) . If the back end of the contacts do not
totally cover the ledge, the contacts should be replaced .
WARNING
ARC CHUTES MUST ALWAYS BE SECURED PROPERLY IN PLACE
BEFORE A CIRCUIT BREAKER IS INSTALLED IN A CIRCUIT BREAKER
COMPARTMENT. FAILURE TO DO THIS COULD RESULTS IN
EQUIPMENT DAMAGE, BODILY INJURY OR EVEN DEATH.
Once the inspection is complete, be sure the arc chutes are
properly replaced as previously described on this page .
Figure 93. Use of Contact Wear Indicator with Circuit Breaker Closed
Breaker Frame Inspection
The breaker frame and wiring should be inspected for nicked
wires, for cracks in plastic parts, and for loose screws . Screws
or bolts should be tightened to levels outlined in
Table 14
.
Loose screws inserted into plastic parts will require thread-lock-
ing compound (such as Loctite 242) . All nicked wiring should be
replaced .
