NEMA - ANSI/NEMA KS 3
GUIDELINES FOR INSPECTION AND PREVENTIVE MAINTENANCE OF SWITCHES USED IN COMMERCIAL AND INDUSTRIAL APPLICATIONS
|Publication Date:||1 January 2010|
NEMA Standards Publication KS 3 sets forth, for use by qualified
personnel1, a number of basic procedures that may be
used for the inspection and preventive maintenance of switches used
in industrial and commercial applications rated up to and
600 V 50/60 Hz ac or ac/dc.
NOTE-Consult the manufacturer for other
The National Electrical Code® defines several switch
types: General Use Switch, Isolating Switch, Motor-Circuit Switch,
and Double-Throw Switch. In most cases, a switch is capable of
Isolating Switch does not have an interrupting rating and is actuated after the circuit has been opened by some other means. A Motor-Circuit Switch is rated in horsepower and is capable of interrupting the maximum overload current of a motor with the
same horsepower rating.
The methods outlined may be used to verify specific
characteristics of a switch that was originally built and tested in
compliance with the requirements of NEMA Standards Publication KS
1. These methods are intended for field application and are,
therefore, non-destructive in nature. Accordingly, these methods cannot be used to verify all performance capabilities of a switch since verification of some capabilities requires tests of a destructive nature.
Many tests, including those of a destructive nature, as defined in KS 1, are performed on representative samples of switches by the manufacturer, as part of a routine program of factory inspection.
The KS 3 Standards Publication is not intended, nor is it
adequate, to verify proper electrical performance of a switch that
has been disassembled, modified, rebuilt, refurbished, or handled
in any manner not intended or authorized by the original
manufacturer. Such switches should be removed from service.
1 For purposes of these guidelines, a qualified
person is one who has skills and knowledge related to the
construction and operation of the electrical equipment and
installation and has received training to recognize and avoid the
hazards involved. In
addition, the person is trained:
-and authorized to test, energize, clear, ground, tag, and
lockout circuits and equipment in accordance with established
-in the proper care and use of protective equipment such as rubber gloves, hard hat, safety glasses or face shields, and flash resistant clothing, in accordance with established safety practices.
-in first aid.