KS 3-2010
Page 9
Section 5
PREVENTIVE MAINTENANCE
5.1 General
Under normal conditions, properly applied switches require maintenance only for verification of
environmental conditions and that the correct enclosure type for those conditions is being used. However,
when inspections determine an abnormal condition and indicate the possibility of damage, it may be
necessary to perform certain maintenance steps. This clause is intended to assist the user in performing
these steps.
These steps cover the only maintenance that should be performed on switches unless specifically
authorized by the switch manufacturer.
5.2 Environmental Evaluation
5.2.1 Purpose
To examine the operating environment and the switch's physical condition. Preventive maintenance and
corrective actions are included as appropriate.
5.2.2 Procedure
WARNING—Follow all safety procedures described in Section 2.
The switch enclosure must be opened to perform the following steps and, in some cases, it will be
necessary to remove the switch from the enclosure.
5.2.2.1 After being properly isolated, examine the switch surfaces for dust, dirt, soot, or moisture. If
evidence of contaminates or moisture is found, or more than a thin film of dust, dirt, or soot is
seen, the switch should be cleaned as suggested below.
The insulating surfaces of the switch should be cleaned using a lint free dry cloth, brush, or vacuum cleaner.
Avoid blowing material into the switch or into surrounding equipment.
CAUTION—Commercial cleaners and lubricants may attack and damage the plastic insulating materials of
the switch. Therefore, such cleaners should not be used. Only the methods described in 5.2.2.1 should be
used. Follow manufacturer’s recommendations for the use of grease.
Steps should be taken to eliminate the source of the contamination or to provide an appropriate enclosure
that will protect against the future entry of contaminants. With respect to the prevention of moisture, the
switch should be housed in an enclosure appropriate for the environment.
5.2.2.2 Examine the switch and terminations for signs of overheating as described in 4.3.2.4. If such
evidence is found, the following maintenance steps should be performed.
5.2.2.2.1 Copper switch terminals and connecting straps (wire connectors and bus bars) can normally
be cleaned. They should be carefully disassembled, cleaned, and dressed, following the manufacturer’s
instructions. All metal and abrasive particles should be removed before reassembling. Care should be
taken to ensure that the switch terminals and connecting straps are properly torqued during re-
installation.
CAUTION—When performing this procedure, extreme care should be exercised to prevent any damage to
plated connections or mechanical disturbance to the switch and to prevent any particles from entering the
switch mechanism, contacts, or arc suppression areas.
© Copyright 2010 by the National Electrical Manufacturers Association.
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