Generac 005031-0 (25kW) owner manual Basic Standby Electric System, Total Circuit Isolation Method

Section 2 — Installation

Liquid-cooled 15, 20 and 25 kW Generators

2.4BASIC 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:

•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.

Figure 2.1 – Basic Standby Electric System

•It must have an ampere rating equal to the total amperage rating of the emergency distribution panel circuit.

•It must be installed between the building’s main distribution panel and the emergency distribution panel.

2.6TOTAL CIRCUIT ISOLATION

METHOD

When a generator capable of powering all electrical loads in the circuit is to be installed, the “Total Circuit Isolation Method” may be used. 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.

2.7GROUNDING THE GENERATOR

A GROUNDING LUG (Figure 2.2) is provided on the generator mounting base for the purpose of ground- ing the frame and the external electrically conductive parts of the equipment to an approved earth ground and/or grounding rods where required by the National Electrical Code. Consult a qualified electri- cian for grounding requirements in the area. Grounding procedures must meet local regulations.

NOTE:

The manufacturer recommends the use of a Generac Power Systems transfer switch in con- junction with this generator.

2.5EMERGENCY CIRCUIT ISOLATION

METHOD

This prevents overloading the generator by keeping electrical loads below the wattage/amperage capacity of the generator. If the generator is powering only crit- ical loads, within its wattage/amperage capacity, dur- ing utility power outages, consider using the emer- gency circuit isolation method.

Critical electrical loads are grouped together and wired into a separate “Emergency Distribution Panel.” The generator only supplies electrical circuits connected to the emergency distribution panel during utility power outages. Load circuits powered by that panel must be within the wattage/amperage capacity of the generator set. The transfer switch must meet the following requirements:

DANGER

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 electrical shock in the event of a ground fault condi- tion in the generator or in connected electrical devices. In addition, grounding helps dissipate static electricity that often builds up in ungrounded devices.

Figure 2.2 – Generator Grounding Lug (typical)

10