Guardian 4389 Repair Manual page 11

GENERAL INFORMATION
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 (next page). Installation of such a
system includes the following:
• Selecting a Location
• Grounding the generator.
• Providing a fuel supply.
• Mounting the load center.
• 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 pow-
ered by the unit, ensuring that there is proper ventila-
tion 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 exces-
sively long wiring runs can result in a voltage drop.
GROUNDING THE GENERATOR
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 grounding lug and to
an earth-driven copper or brass grounding-rod (elec-
trode). Consult with a local electrician for grounding
requirements in your area.
THE FUEL SUPPLY
Prepackaged units with air-cooled engines were oper-
ated, tested and adjusted at the factory using natural
gas as a fuel. These air-cooled engine units can be
converted to use LP (propane) gas by making a few
adjustments for best operation and power.
LP (propane) gas is usually supplied as a liquid in
pressure tanks. Both the air-cooled and the 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.
PART 1
PREPACKAGED INSTALLATION BASICS
The pressure at which LP gas is delivered to the gen-
erator 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 regulator is required to maintain cor-
rect gas supply pressures.
Current recommended gaseous fuel pressure at the inlet
side of the generator fuel solenoid valve is as follows:
Minimum water column
Maximum water column
Note: Some older NG product was rated at 11-14
inches water column.
A primary regulator is required to ensure that proper
fuel supply pressures are maintained.
DANGER: LP AND NATURAL GAS ARE BOTH
!
HIGHLY EXPLOSIVE. GASEOUS FUEL LINES
MUST BE PROPERLY PURGED AND TESTED
FOR LEAKS BEFORE THIS EQUIPMENT IS
PLACED INTO SERVICE AND PERIODICALLY
THEREAFTER. PROCEDURES USED IN
GASEOUS FUEL LEAKAGE TESTS MUST
COMPLY STRICTLY WITH APPLICABLE FUEL
GAS CODES. DO NOT USE FLAME OR ANY
SOURCE OF HEAT TO TEST FOR GAS
LEAKS. NO GAS LEAKAGE IS PERMITTED.
LP GAS IS HEAVIER THAN AIR AND TENDS
TO SETTLE IN LOW AREAS. NATURAL GAS
IS LIGHTER THAN AIR AND TENDS TO SET-
TLE IN HIGH PLACES. EVEN THE SLIGHTEST
SPARK CAN IGNITE THESE FUELS AND
CAUSE AN EXPLOSION.
Use of a flexible length of hose between the genera-
tor fuel line connection and rigid fuel lines is required.
This will help prevent line breakage that might be
caused by vibration or if the generator shifts or set-
tles. The flexible fuel line must be approved for use
with gaseous fuels.
Flexible fuel line should be kept as straight as possi-
ble between connections. The bend radius for flexible
fuel line is nine (9) inches. Exceeding the bend radius
can cause the fittings to crack.
THE TRANSFER SWITCH / LOAD CENTER
A transfer switch is required by electrical code, to pre-
vent electrical feedback between the utility and stand-
by power sources, and to transfer electrical loads
from one power supply to another safely.
PREPACKAGED TRANSFER SWITCHES:
Instructions and information on prepackaged transfer
switches may be found in Part 3 of this manual.
SECTION 1.2
LP NG
11 inches 5 inches
14 inches 7 inches
Page 9