Generator Mounting And Support; Basic Standby Electric System; Emergency Circuit Isolation Method; Total Circuit Isolation Method - Generac Power Systems 004920-0 Owner's Manual

2.3 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 six inches thick and should
extend beyond the enclosure to a distance of at least
three inches on all sides.
2.4 BASIC STANDBY ELECTRIC
SYSTEM
Figure 2.1 shows a schematic diagram of a basic
standby electric system. Both the UTILITY power
supply and the STANDBY (GENERATOR) output are
connected to an approved transfer switch. The trans-
fer switch is required by electrical code and serves
the following functions:
• Allows 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.
Both the STANDBY and the UTILITY power supplies
to the transfer switch are protected against overload
by a main line circuit breaker.
Generac recommends the use of a Generac Power
Systems "pre-pack" type transfer switch in con-
junction with this generator.
Figure 2.1 – Basic Standby Electric System
NOTE:
Section 2 — Installation
Generac Liquid-cooled 20 kW Generator
2.5 EMERGENCY CIRCUIT ISOLATION
METHOD
This method prevents overloading the generator by
keeping electrical loads below the wattage/amperage
capacity of the generator. If the generator is powering
only critical loads, within the wattage/amperage
capacity, during utility power outages, consider using
the emergency circuit isolation method.
Critical electrical loads are grouped together and
wired into a separate "Emergency Distribution
Panel." Load circuits powered by that panel are with-
in the wattage/amperage capacity of the generator set.
When this method is used, it is difficult to overload
the generator. The transfer switch must meet the fol-
lowing 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 dis-
tribution panel and the emergency distribution
panel.
2.6 TOTAL CIRCUIT ISOLATION
METHOD
When a generator capable of powering all electrical
loads in the circuit is to be installed, the "Total
Circuit Isolation Method" can be used. 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.
2.7

GROUNDING THE GENERATOR

The National Electrical Code requires the frame and
external electrically conductive parts of this equip-
ment to be properly connected to an approved earth
ground and/or grounding rods. For that purpose, a
GROUND LUG (Figure 2.2 on page 12) is provided on
the generator mounting base. Consult a qualified
electrician for grounding requirements in the 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.
Generac
DANGER
® Power Systems, Inc. 11