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Generac
®
Power Systems, Inc. 9
GENERATOR MOUNTING AND SUPPORT
Retain the generator compartment to a concrete slab
with 1/4-inch masonry type anchor bolts. Be sure the
bolts are long enough to retain the compartment. The
slab should be at least 6 inches thick and should extend
beyond the enclosure to a distance of at least 3 inches
on all sides. See pages 54-55 for generator major
dimensions.
BASIC STANDBY ELECTRIC SYSTEM
Figure 2.1 shows a schematic diagram of a basic stand-
by electric system. Both the UTILITY power supply and
the STANDBY (generator) output are connected to an
approved transfer switch. The transfer switch is
required by electrical code and serves the following
functions:
• Permits the LOAD circuits to be connected to only one
power supply at a time.
• Prevents electrical backfeed between the generator
and the UTILITY power circuits.
Notice that both the STANDBY and the UTILITY power
supplies to the transfer switch are protected against
overload by a main line circuit breaker.
NOTE:
Generac recommends the use of a Generac power
systems “GTS” type transfer switch in conjunction
with this generator.
Figure 2.1 – Basic Standby Electric System
EMERGENCY CIRCUIT ISOLATION
METHOD
This prevents overloading the generator by keeping elec-
trical loads below the wattage/amperage capacity of the
generator. If the generator is powering only critical
loads, within the wattage/amperage capacity, during util-
ity power outages, you might consider using the emer-
gency circuit isolation method.
Critical electrical loads are grouped together and wired
into a separate “Emergency Distribution Panel.” Load
circuits powered by that panel are within the
wattage/amperage capacity of the generator set. When
this method is used, it is difficult to overload the gener-
ator. The transfer switch must meet the following
requirements:
• It must have an ampere rating equal to the total
amperage rating of the emergency distribution panel
circuit.
• Have it installed between the building’s main distri-
bution panel and the emergency distribution panel.
TOTAL CIRCUIT ISOLATION METHOD
When a generator capable of powering all electrical
loads in the circuit is to be installed, you may use the
“Total Circuit Isolation Method.” It is possible for the
generator to be overloaded when this isolation method
is employed. The following apply to the transfer switch
in this type of system.
• Ampere rating of the transfer switch must equal the
ampere rating of the normal incoming utility service.
• The transfer switch is installed between the utility
service entrance and the building distribution panel.
GROUNDING THE GENERATOR
The National Electrical Code requires the frame and
external electrically conductive parts of this equipment
to be properly connected to an approved earth ground
and/or grounding rods. For that purpose, a GROUND
LUG (Figure 2.2) is provided on the generator mounting
base. Consult a qualified electrician for grounding
requirements in your area. Grounding procedures must
meet local regulations.
Do not connect the ground wire to any pipe that
carries a flammable or explosive substance – FIRE
or an EXPLOSION may result.
Proper grounding helps protect personnel against elec-
trical shock in the event of a ground fault condition in
the generator or in connected electrical devices. In addi-
tion, grounding helps dissipate static electricity that
often builds up in ungrounded devices.
Figure 2.2 – Generator Grounding Lug (typical)
Section 2 — Installation
Guardian Liquid-cooled 15 kW, 20 kW and 25 kW Generators