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Electrical Connections
A
3.1
A - Tin Plated Aluminum to Tin Plated Aluminum
Bus Bars or
B - Tin Plated Aluminum to Silver Plated Copper
Bus Bars
1. Cap Screw
2. Flat Washer
3. "Belleville" Washer 3.1 Before Torquing
3.2 After Torquing
4. Nut
Figure 19. Bus Bar Joint Assembly
Bus Insulation
Bus and connections are insulated in metal-clad switchgear as
part of a coordinated insulation system. Air or creep distance plus
bus insulation combines to provide the needed insulation level.
BUS INSULATION IS NOT DESIGNED TO PREVENT SHOCK.
Hazardous voltages.
Will cause death, severe personal injury, and
property damage.
Do not contact energized conductors.
De-energize and properly ground high voltage con-
ductors before working on or near them.
26
Courtesy of NationalSwitchgear.com
0.0
0.1
0.12
0.18
0.5
4.628
5.579
2.586
6.211
3.093
0.05
0.13
0.0
0.1
CENTER
Legend
DANGER
0.12
0.1
0.18
0.5
0.05
0.1
0.13
0.0
0.0
14.74
19.30
DIM_DIM
CENTER
B
3.2
0.1
0.18
0.5
0.0
0.12
0.0
0.13
0.1
0.05
35.096
CENTER
10.531
3.276
24.076
5.028
21.857
C - Silver Plated Copper to Silver Plated Copper
Bus Bars
1. Cap Screw
2. Flat Washer
4. Nut
5. Flat Washer
6. Lock Washer
Epoxy insulation applied in a fluidized bed process is normally
furnished on the bus bars. Bus joints are normally insulated
with boots. Taping is also used for bus joint insulation.
The ANSI requirements for bus insulation in metal-clad
switchgear are contained in ANSI C37.20.2 clause 6.2.3, which
reads as follows:
This insulating covering is a requirement of metal-clad
switchgear and is provided to minimize the possibility of
communicating faults and to prevent development of
bus faults that would result if foreign objects momen-
tarily contacted bare bus. This insulating covering is
usually only a part of the primary insulation system
and in such cases the outer surface of this insulating
covering will not be at ground potential. It should not
be assumed, therefore, that personnel can contact
this insulating covering with complete safety.
C
6
4
5
2
2
1
1
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