– five times for nuts and other screws.
Screws in engagement with a thread of insulating material are completely removed and reinserted each
time.
When testing terminal screws and nuts, a flexible conductor of the largest cross-sectional area specified
in 25.2 is placed in the terminal.
The test is made by means of a suitable test screwdriver, spanner, or key applying a torque as shown in
Table 9, the appropriate column being:
– for metal screws without heads, if the screw when tightened does not protrude from the
hole
–
I
– for other metal screws and for nuts – II
– for screws of insulating material:
• having a hexagonal head with the dimension across flats exceeding the overall thread
diameter; or
• with a cylindrical head and a socket for a key, the socket having a cross-corner
dimension exceeding the overall thread diameter; or
• with a head having a slot or cross slots, the length of which exceeds 1,5 times the
overall thread diameter – II
– for other screws of insulating material – III
Table 9 – Torque for testing screws and nuts
Nominal diameter of screw
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