Prepackaged Installation Basics; Home Standby - Guardian 4721 Repair Manual

SECTION 1.2

PREPACKAGED INSTALLATION BASICS

INTRODUCTION
Information in this section is provided so that the ser-
vice technician will have a basic knowledge of instal-
lation requirements for prepackaged home standby
systems. Problems that arise are often related to poor
or unauthorized installation practices.
A typical prepackaged home standby electric system
is shown in Figure 1, below. Installation of such a sys-
tem includes the following:
• Selecting a Location
• Mounting of the generator.
• Grounding the generator.
• Providing a fuel supply.
• Mounting the transfer switch.
• Connecting power source and load lines.
• Connecting system control wiring.
• Post installation tests and adjustments.
SELECTING A LOCATION
Install the generator set as close as possible to the
electrical load distribution panel(s) that will be powered
by the unit, ensuring that there is proper ventilation for
cooling air and exhaust gases. This will reduce wiring
and conduit lengths. Wiring and conduit not only add to
the cost of the installation, but excessively long wiring
runs can result in a voltage drop.
MOUNTING THE GENERATOR
Mount the generator set to a concrete slab. The slab
should extend past the generator and to a distance of at
least twelve (12) inches on all sides. The unit can be
retained to the concrete slab with masonry anchor bolts.
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The National Electric Code requires that the frame
and external electrically conductive parts of the gen-
erator be property connected to an approved earth
ground. Local electrical codes may also require prop-
er grounding of the unit. For that purpose, a ground-
ing lug is attached to the unit. Grounding may be
accomplished by attaching a stranded copper wire of
the proper size to the generator's grounding lug and
to an earth-driven copper or brass grounding-rod
(electrode). Consult with a local electrician for ground-
ing requirements in your area.
Units with liquid cooled engines are shipped from the
factory to run on natural gas (Figure 2). Units that will
use LP (propane) gas fuel (Figure 3) must be convert-
ed in the field per instructions located in the
Installation Manual.
LP (propane) gas is usually supplied as a liquid in
pressure tanks. Liquid cooled units require a "vapor
withdrawal" type of fuel supply system when LP
(propane) gas is used. The vapor withdrawal system
utilizes the gaseous fuel vapors that form at the top of
the supply tank.
The pressure at which LP gas is delivered to the gen-
erator's fuel solenoid valve may vary considerably,
depending on ambient temperatures. In cold weather,
supply pressures may drop to "zero". In warm weath-
er, extremely high gas pressures may be encoun-
tered. A primary/secondary supply regulator is
required to maintain correct gas supply pressure to
the generator demand regulator.
Minimum recommended gaseous fuel pressure at
the inlet side of the generator's fuel solenoid valve is
Figure 1. Typical Prepackaged Installation
PART 1
GENERAL INFORMATION
GROUNDING THE GENERATOR
THE FUEL SUPPLY