PB 1.1-2007
Page 18
CAUTION—Do not remove plating from aluminum parts in joints or terminations. Damage to plating can
result in overheating. Replace damaged aluminum parts.
10.4.3 Fuse Clip Contact Pressure and Contact Means
Examine fuse clip contact pressure and contact means. If there is any sign of overheating or looseness,
follow the manufacturer’s maintenance instructions or replace the fuse clips. Loose fuse clips can result in
overheating.
10.4.4 Plug Fuses
Re-tighten plug fuses.
10.4.5 Conditions Which Caused Overheating
Be sure that all conditions which caused the overheating have been corrected.
10.5 PROPER AMPERE, VOLTAGE, AND INTERRUPTING RATINGS
Check circuit breakers, switches, and fuses to ensure they have the proper ampere, voltage, and
interrupting ratings. Ensure that non-current-limiting devices are not used as replacements for current-
limiting devices. Never attempt to defeat rejection mechanisms which are provided to prevent the installation
of the incorrect class of fuse.
10.5.1 Mechanisms Free and in Proper Working Order
Operate each switch or circuit breaker several times to ensure that all mechanisms are free and in proper
working order. Replace as required. See NEMA AB-4 for maintenance of molded case circuit breakers.
10.6 OPERATION OF ALL MECHANICAL COMPONENTS
Check the operation of all mechanical components. Replace as required.
10.6.1 Switch Operating Mechanisms
Exercise switch operating mechanisms and external operators for circuit breakers to determine that they
operate freely to their full on and off positions.
10.6.2 Integrity of Electrical and Mechanical Interlocks
Check the integrity of all electrical and mechanical interlocks and padlocking mechanisms. For key
interlocked systems, assure that only the required number of keys are accessible to the operator.
10.6.3 Missing or Broken Parts
Whenever practical, check all devices for missing or broken parts, proper spring tension, free movement,
corrosion, dirt, and excessive wear.
10.6.4 Manufacturer’s Instructions
Adjust, clean, and lubricate or replace parts according to the manufacturer’s instructions.
10.6.4.1 Clean Nonmetallic Light Grease or Oil
Use clean nonmetallic light grease or oil as instructed.
10.6.4.2 Molded Case Circuit Breakers
Do not oil or grease parts of molded case circuit breakers.
© Copyright 2007 by the National Electrical Manufacturers Association.
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