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Generac
®
Power Systems, Inc. 9
Figure 2.1 – Basic Standby Electric System
2.2 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 its wattage/amperage capacity,
during 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.” 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 or greater
than the total amperage rating of the emergency dis-
tribution panel circuit.
• It must be installed between the building’s main distri-
bution panel and the emergency distribution panel.
2.3 TOTAL CIRCUIT ISOLATION METHOD
When a generator capable of powering all electrical
loads in the circuit is to be installed, use the “Total
Circuit Isolation Method.” It is possible for the genera-
tor 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 be equal to
or greater than the ampere rating of the normal
incoming utility service.
• The transfer switch must be installed between the
utility service disconnect circuit breaker and the
building distribution panel.
2.4 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 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.
Proper grounding helps protect personnel against electri-
cal shock in the event of a ground fault condition 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)
2.5 GENERATOR AC NEUTRAL
CONNECTIONS
Generac uses an UNGROUNDED AC neutral. Grounding
is recommended only at the main service entrance.
2.6 TRANSFER SWITCH START SIGNAL
CONNECTIONS
2.6.1 PRE-PACKAGED TYPE SWITCH
Connect the six signal wires from the automatic trans-
fer switch to the engine generator control, which is
located on the upper right side and inside the lower
control panel. Match wires 23, 194, N1, N2, T1 and T2
in the transfer switch to the corresponding wires on the
terminal strip in the lower panel. The conductors for
these wires should be in a separate conduit from the
main AC output wires.
2.6.2 “GTS” Type Engineered Switch
Connect the two-wire start signal from the automatic
transfer switch to the automatic start connection, which is
located in the right hand corner inside the lower panel.
Match wires 178 and 183 in the transfer switch to 178
and 183 on the terminal strip in the control panel. The
conductors for the two-wire start circuit must be in their
own conduit.
NOTE:
When using a GTS switch, it is necessary to connect
a 240V AC supply to N1 and N2 terminals
of the generator to provide for battery charging.
Wires T1, T2, 23 and 194 should not be
connected.
DANGER
Section 2 — Installation
Guardian Liquid-cooled 40 kW Generator