Ground; Neutral; Ground-Fault Protection Field Connection And Testing; Fuse Selection - GE ABB ReliaGear SB Installation, Operation And Maintenance Manual

I N S TA L L AT I O N , O P E R AT I O N S A N D M A I N T E N A N C E M A N U A L

Ground

The ground bus is factory installed and is bolted
to the uprights of the rear frame structure either
at the top or the bottom of the enclosure. It is
arranged so that connections to the source ground
can be made in any unit. A ground lug is included
in each complete equipment for tying the
switchboard to the station ground. Ground-sense
relays are recommended for protection of the
switchboard.

Neutral

The neutral bus is factory installed and bolted to
the uprights of the frame either at the top or
bottom of the enclosure. It is arranged such that
connections to the source neutral can be made in
any unit. All neutrals, auxiliary neutrals, and
grounds will come pre-installed in all units.
Ground-fault protection field connection and
testing
When ground-fault protection is provided, all field
connections must be made correctly to insure
proper functioning of the ground-fault protection
system. Observe the following rules when
connecting and testing ground-fault protection
systems, as illustrated in Figures 44 and 45.
• In a service entrance section, bond the neutral
conductor to the switchboard ground bus with a
main bonding jumper (ground strap). Locate this
grounding point on the neutral conductor on the
supply side of any ground-fault sensors involving
the neutral conductor. Do not make grounding
connections to the neutral conductor on the load
side of the service disconnect
• On load feeders, run all phase conductors (and
neutral, if used) through the sensor window(s),
with all in the same direction with respect to
sensor polarity
• Do not run equipment ground conductors
through ground-fault sensors. Connect them
directly to the switchboard ground bus, not to
the neutral bus
• Connect the service grounding electrode (water
pipe, etc.) to the lug provided on the switchboard
ground bus for this purpose
• Whenever a service is derived from a grounded
neutral supply, the grounded neutral conductor
must be brought into the service-entrance
equipment, even if the grounded conductor is not
needed for the load supplied by the service. This
is required to provide a low- impedance ground-
fault current return path to the neutral to assure
operation of the overcurrent device, for safety to
personnel and property
• Refer to publication GEI-48907 for instructions
on conducting performance test of new
installations of ground-fault protection systems.

Fuse selection

Select the proper fuses for each circuit based on
load characteristics and available short-circuit
current at the line terminals of the switchboard.
Select a fuse for which the rating of the
combination fuse and switch equals or exceeds
the available short-circuit current. Removable
link-type fuses are not recommended.
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