SECTION 26 2417
DISCONNECT SWITCHES
PART 1
GENERAL
1.1
SECTION INCLUDES
A.
1.2
Safety disconnect switches.
REFERENCES
A.
National Electrical Manufacturers Association (NEMA).
B.
Underwriters' Laboratories, Inc. (UL).
1.3
SYSTEM DESCRIPTION
A.
1.4
Disconnect switches provide safe disconnecting of electrical power to equipment.
SUBMITTALS
A.
Submit the following information in accordance with Division 01:
1. Outline drawing with dimensions.
2. Equipment Ratings.
a. Voltage.
b. Capacity.
c. Horsepower.
d. Short circuit withstand rating.
1.5
QUALIFICATIONS
A.
Safety switches shall be NEMA heavy-duty type and shall carry the UL label. Fusible
switches shall incorporate Class "R" fuse rejection feature and shall be braced to withstand
50,000 ampere RMS symmetrical fault current.
B.
Switches shall be of the same manufacturer as the panelboards.
C.
Safety switches used for service entrance equipment shall be UL listed as suitable for service
entrance.
IDPS Fleet and Supply Building
414222-0
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SECTION 26 2417
DISCONNECT SWITCHES
PART 2
PRODUCTS
2.1
REQUIREMENTS
A.
Provide heavy-duty type, sheet steel enclosed, safety switches. Type, size, and rating shall be
as shown on the drawings or as required by the motor or equipment served.
B.
Switches shall incorporate quick-make, quick-break operating handles. Mechanism shall be an
integral part of the box, not the cover, and switches shall have a cover interlock to prevent
unauthorized opening of the switch door in the on position or closing of the switch mechanism
with the door open. Current carrying parts shall be constructed of high-conductivity copper
with silver-tungsten type switch contact.
C.
Fuse clips shall be positive pressure type reinforced rejection type fuse clips.
D.
Indoor enclosures shall be NEMA 1. Enclosures for wet locations and for outdoor use shall be
NEMA 3R.
E.
Terminals of the proper size for wire as shown on the drawings for line, load and ground shall
be supplied by the disconnect switch manufacturer.
PART 3
EXECUTION
3.1
INSTALLATION
A.
Furnish and install safety disconnect switches (fused and non-fused) shown on the drawings.
In addition, furnish a safety disconnect switch for motors and equipment which do not have
combination starters or integral disconnecting means.
B.
For mechanical equipment rated for use only with fuses (such as condensing units,
compressors, chillers), provide fusible disconnect switches. Such switches shall be one, two
or three pole type, with solid neutral for 4- wire service, and shall have the proper current and
voltage rating as required.
C.
Each motor shall be individually protected. Furnish a safety disconnect for each motor as
required by the NEC.
D.
Disconnect switches shall not be directly mounted to equipment which is mounted on
vibration isolation pads or springs, unless a piece of flexible conduit is used between the
disconnect switch and the fixed conduit.
E.
Safety switches shall be mounted securely to walls, columns or machine frames, and provided
with brackets, mounting devices, structural pieces and expansion type anchor inserts necessary
for this purpose. Switches shall not be mounted directly to metal surfaces or to concrete or
masonry walls. Structural channels such as Kindorf or 3/4" plywood shall be used to mount
switches at least 3/4 inch away from the mounting surface.
F.
Switches shall be mounted at a height of 60 inches above the finished floor to the top of the
back box.
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SECTION 26 2417
DISCONNECT SWITCHES
G.
Coordinate fusible switches and fuse sizes, with mechanical trades, where required by UL
listing for mechanical equipment installation.
H.
Motors larger than 1/8 horsepower and controllers shall have a disconnecting means within
sight and within 50'.
1. Combination motor starters, circuit breakers in panelboards, manual motor starters,
integral disconnecting means on equipment, and cord/plug connections may be used as
disconnecting means where they are within sight and 50' of the equipment.
2. Switches, combination starters, and circuit breakers which are pad-lockable in the "OFF"
position may be used as disconnecting means when not in sight or within 50' unless
prohibited by local code.
3. Provide a disconnect switch for motors, motor-driven appliances, and controllers not
covered by paragraphs 1 or 2 above.
I.
Transformers shall have a disconnecting means (primary and secondary) within sight and
within 50'.
1. Provide primary non-fused disconnect switches where the primary over-current device is
more than 50' or not in sight of the transformer.
2. Provide secondary fused disconnect switches or separately enclosed circuit breakers
where the secondary over-current device is required to meet the 10 foot or 25 foot tap
rule of the currently enforced edition of the national electrical code.
END OF SECTION 26 2417
IDPS Fleet and Supply Building
414222-0
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