4-11
GROUNDING
Typical requirements for bonding and grounding are
given in the National Electrical Code, 1990, Article 250.
Periodic inspection is recommended, especially after
service work has been performed on equipment any-
where in the electrical system.
Generator Set Bonding and Equipment
Grounding
Bonding is defined in the National Electrical Code, 1990,
Article 100, as: The permanent joining of metallic parts to
form an electrically conductive path which will assure
electrical continuity to conduct safely any current likely to
be imposed.
Bonding and equipment grounding
must be done correctly for proper system operation
and operator safety. Abnormal system conditions
may allow ungrounded metallic parts to be ener-
gized, which could result in severe personal injury or
death.
Circuit and System Grounding
The design and installation of grounding systems in-
volves many factors, including multiple transformers,
standby generators, ground fault protection, physical lo-
cations of equipment, and conductor type and size. Al-
though the consulting engineer and installer are respon-
sible for the design and wiring of each particular ground-
ing application, system grounding must conform to na-
tional and local codes.
Output Lead Markings
Leads on revolving field generators are marked T1, T2,
etc. These identifying marks also appear on the wiring
diagram.
SWITCHBOARD
Electrical shock can cause severe per-
sonal injury or death. Use extreme caution when
working on electrical circuitry. Attach and remove
switchboard leads only when generator set is not op-
erating. Make certain that the generator set is inop-
erative by disconnecting the negative (-) battery ca-
ble. Do not touch leads during operation of genera-
tor set.
A optional wall-mounted switchboard contains amme-
ters, a voltmeter, and circuit breakers. If it is used, the fol-
lowing connections apply:
1. Connect one ungrounded (hot) generator lead to
the unused terminal on each ammeter.
2. Connect the generator lead and load wires to be
grounded to the ground stud on the switchboard.
3. Connect one ungrounded (hot) load wire to the un-
used terminal on each circuit breaker.
4. On sets that generate more than one voltage (ex-
ample: 120/240), wire the voltmeter to indicate the
higher voltage.
RECONNECTIBLE GENERATORS
The factory ships special-order sets with control panels
especially wired for the voltage specified by the cus-
tomer. Standard sets without instruments are shipped
with the T1-T4 or T1-T12 output leads separated in the
output box. These single-phase and broad-range gen-
erators may be connected to provide any of the output
voltages shown in Figure 4-12. Grounding or earthing
procedures should comply with local electrical codes.
Electrical shock can cause severe per-
sonal injury or death. Never remove the grounding
pin from electrical equipment. Incorrect ground or
no ground can cause the installation to become elec-
trically “hot”. Equip the installation with adequate
Ground-Fault Circuit Protection devices to meet the
National Electrical Code (NFPA 70, 551- 7[C]) and to
provide personal safety.
Code 3C or 53C Reconnectible Generators:
The sin-
gle-phase, 60- and 50-hertz generators have output
leads T1, T2, T3 and T4 available to make the single
phase voltage and load connections shown in Figure
4-12 at the installation site.
Code 18 or 518 Reconnectible Generators:
The
three-phase, broad-range, 60 and 50 hertz 12-lead gen-
erators have output leads T1 through T12 available to
make the single and three phase voltage load connec-
tions shown in Figure 4-12.
When connecting the output leads, be sure to connect
jumper W10 on the voltage regulator printed circuit board
between terminal V4 (common) and V1, V2, or V3 as
listed on the reconnection diagram.
Code 9x Generators:
These special-order three-
phase, 60 hz, 4-wire generators are rewired at the factory
to provide 347/600 VAC. Output leads T1, T2, T3 and T0
are available for connection to the load wires. See con-
nection diagram, Figure 4-12.
BATTERY CONNECTIONS
The battery is connected for negative (-) ground, Figure
4-13. Be sure all battery connections are tight.
Battery polarity must agree with the rectifier in the control
box. If battery polarity must be changed, reverse the rec-
tifier connection in the control box.
