Generac 004189-1, 004188-1, 004475-1 Basic Standby Electric System, Total Circuit Isolation Method

Section 2 — Installation

Guardian Liquid-cooled 15 kW, 20 kW and 25 kW Generators

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

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)

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.

Generac® Power Systems, Inc. 9