Total Circuit Isolation Method; Grounding The Generator; Generator Ac Neutral Connections; Transfer Switch Start Signal Connections - Generac Power Systems Guardian 004988-1 Owner's Manual

• 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 dis-
tribution panel and the emergency distribution
panel.
2.6 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 gener-
ator 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.
2.7

GROUNDING THE GENERATOR

The National Electrical Code requires the frame and
external electrically conductive parts of this equip-
ment 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 gener-
ator mounting base. Consult a qualified electrician
for grounding requirements in the area. Grounding
procedures must meet local regulations.
Figure 2.2 – Generator Grounding Lug (typical)
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.
10 Generac ® Power Systems, Inc.
Section 2 — Installation
Guardian Liquid-cooled 27 kW and 30 kW Generators
GROUNDING
LUG
2.8 GENERATOR AC NEUTRAL
CONNECTIONS
Generac uses an UNGROUNDED AC neutral.
Grounding is recommended only at the main service
entrance. If the neutral wire is grounded and one of
the phase loads becomes grounded, the excessive
current opens the load circuit breaker or collapses
the generator field. The actual result depends on the
electrical characteristics of the particular installed
generator.
2.9 TRANSFER SWITCH SIGNAL
CONNECTIONS
2.9.1 PRE-PACKAGED ATS
If the generator is to be installed with a pre-packaged
transfer switch, it is necessary to connect the control
wires to the generator and set position two of the
four-position dip switch to OFF .
Setting switch two to OFF allows the control PCB to
perform the ATS control functions.
Control system interconnections consist of N1 and
N2, and leads 23 and 194. Control system intercon-
nection leads must be run in a conduit that is sepa-
rate from the AC power lead. Recommended wire
gauge sizes for this wiring depends on the length of
the wire, as recommended below:
MAXIMUM WIRE LENGTH
460 feet (140m)
461 to 730 feet (223m)
731 to 1,160 feet (354m)
1,161 to 1,850 feet (565m)
2.9.2 GTS-TYPE ATS
If the generator is to be installed with an automatic
transfer switch, such as an engineered Generac GTS-
type switch, it is necessary to connect the two-wire
start control system.
Connect the two-wire start signal from the automatic
transfer switch to the automatic start connection,
which is located in the middle, on the bottom, inside
the control 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. (See
Section 3.1 for further explanation.)
RECOMMENDED WIRE
SIZE
No. 18 AWG.
No. 16 AWG.
No. 14 AWG.
No. 12 AWG.