53
UL508
Table 54.1 , Tightening torque for screws
Test wire size installed
in connector (AWG)
Tightening torque (lb in.)
Slotted head no 10 and large
Hexagonal head - external drive socket
wrench
Slot width - 0.047 inch
or less and slot length
1/4 inch or less
Slot width - 0.047
inch or slot length -
over 1/4 inch
Split bolt connectors
other connectors
18-10
20
35
80
75
8
25
40
80
75
6-4
35
45
165
110
3
35
50
275
150
2
40
50
275
150
1
-
50
275
150
1/0 - 2/0
-
50
385
180
3/0-4/0
-
50
500
250
250-350
-
50
650
325
400
-
50
825
375
500
-
50
825
375
600-750
-
50
1000
375
800-1000
-
50
1100
500
1250-2000
-
-
1100
600
Note : For values of slot width or length not corresponding to those specified, the largest torque value associated
with the conductor size shall be marked. Slot width is the normal design value. Slot length shall be measured at
the bottom of the slot
Table 54.2 , Tightening torque for slotted head screws smaller than No. 10 intended for use with 8
AWG or smaller conductors
Slot length of screw
a
Tightening torque, lb.in
Slot width of screw
b
smaller
than 0.047 in
Slot width of screw
b
0.047 in
and larger
<5/32
7
9
5/32
7
12
3/16
7
12
7/32
7
12
1/4
9
12
9/32
-
15
Above 9/32
-
20
a
For slot length of intermediate values, torques pertaining to next shorter length shall be utilized. For
screws with mulitple tightening means, the largest torques value associated with the conductor size
shall be marked. Slot length shall be measured at the bottom of the slot
b
Slot width is the nominal design value
DEH40603
– Page 7
AN 12-1007 Rev 05, 04/04/2012
