Instructional Leaet IL019117EN Effective July 2016
Supersedes December 2015
Installation guidelines for users of MagnumDS
Low-Voltage Rear-Access Switchgear Assemblies
for seismic applications
A representative Type Magnum DS®Low-Voltage
Rear-Access Switchgear Assembly was attached
to a seismic table and shaken to simulate the
effects of an earthquake. The test exceeded the
requirements of the 2012 International Building
Code (IBC), the 2013 California Building Code (CBC),
and OSHPD Seismic Pre-certification (OSP). The
following guidelines were developed as a result of
that test program, and they apply to standard and
arc-resistant switchgear:
1. When Magnum DS Switchgear is subjected
to an earthquake, it pulls on its foundation.
The importance of an adequate foundation
cannot be over emphasized; in fact, proper
mounting is the single most important factor in
withstanding a seismic event. The foundation
must be level and continuous under the
entire switchgear assembly. The foundation
must be designed to withstand the reaction
loads imposed on it by the equipment. The
foundation must be designed to hold a quantity
of six ½-13 SAE Grade 5 bolts per section.
The anchoring system must be strong enough
to prevent “pull-out” of these bolts. The
anchoring system should be put into place
prior to switchgear installation to reduce
effort associated with anchoring. Welding
to embedded steel members is acceptable,
provided the weld strength is equivalent to
that of six SAE Grade 5 bolts specified. For
nuclear installations, weld per AWSD1.1,
alternatively, welding procedures and
personnel qualifications may be performed
IAW ASME BPVC Section IX and the
inspections be performed IAW AWS D1.1,
and/or D1.3 and/or D9.1. See foundation
drawings provided for the specific project
to identify anchoring locations.
2. When Magnum DS Switchgear is subjected to
an earthquake, it moves. The amount of motion
depends on the magnitude of the earthquake.
Eaton Pow-R-Way®and non-segregated phase
bus ducts, and their associated switchgear
flanges have been seismically qualified as
a system. If other types of top entry, i.e.,
conduits, are necessary, attachments must be
capable of accommodating a 3-inch front-to-
back and side-to-side (6 inches peak-to-peak)
cabinet motion.
3. Center of gravity
For seismic calculations, the following
dimensions should be used to locate the
approximate center of gravity for Magnum DS
switchgear. They are applicable to all types
of line-ups:
Vertical 60 inches
From left-to-right Center of line-up
From front One-half the depth
of the switchgear
Enclosure weights are found on the equipment
drawings provided for the specific project. Add
breaker weights to enclosure weight.
4. When a switchgear assembly is separated
into groups of vertical sections for shipment,
the user must be sure to install all of the inter-
unit tie bolts (see drawing 9253C18). Failure
to join the shipping groups together properly
could result in damage to the equipment
during an earthquake.
5. It is recommended that incoming power
cables be lashed together at least every
4 feet within the switchgear.
6. The drawout Magnum DS power circuit
breakers should always remain in the
connected position, or they should be
secured remote from the switchgear.
7. The user should provide storage areas to
secure mobile pieces of equipment (such as
breaker lifting trucks, spare breakers, hand
trucks, etc.) away from the switchgear so it
is not damaged by being bumped during an
earthquake. When the optional top-of-gear
traveling circuit breaker lifter is provided, it
must be secured in place with the hardware
provided when not in use. Refer to the
operating instructions provided with the
switchgear for the details of this procedure.
