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C-25
Connections
The quality of bar connections depends, among other things, on the tightening
torques used for the nuts and bolts. Over-tightening may have the same
consequences as under-tightening.
The correct tightening torques for the connection of bars to the circuit-breaker
terminals are indicated in the table below.
The values below are for copper bars (Cu ETP-NFA51-100) and steel nuts and bolts
(class 8.8).
The same values apply to AGS-T52 quality aluminium bars
(French standard NFA 02-104 and American National Standard H-35-1).
Examples of bar connections
Tightening torque for bars
Rated diameter (mm) Drilling (mm) Tightening torque (Nm) Tightening torque (Nm)
diameter
with flat or grower
with contact or split
washers
washers
10
11
37.5
50
Bar drilling
Examples
Insulation distance
Bar bending
Bars must be bent according to the table below. A tighter bend may cause cracks.
Dimensions (mm)
e
Radius r
Minimum Recommended
5
5
7.5
10
15
18 to 20
terminal screws, factory tightened to 13 Nm
1
circuit-breaker terminal
2
bars
3
bolt
4
washer
5
nut
6
Dimensions (mm)
Utilisation voltage
X minimum
Ui
y
600 V
8 mm
Ui
y
1000 V
14 mm
DB128361
4 5
3 2
6
1
DB128362
DB128363
DB128364
DB128365
DB128367
DB128366
DB128368
X
DB128369
e
r