On terminals all bolts/nuts are subject to 50 Hz or 60 Hz vibration of the electric power in cables and terminal lugs loosen not only from vibration but also from thermal cycling when power is turned off to a machine. Loosening of nuts fixing terminal lugs may cause electrical resistance via heat up of the terminal strip/block as well.
Originally, steps to prevent loosening had been used including double nuts and the use of spring washers but vibrations during transportation and micro vibrations that occur after installation had resulted in frequent loosening. By switching to the HARDLOCK® nut all problems related to loosening were completely solved. Because loosening does not occur, both the number of inspections and re-tightening work has been significantly reduced resulting in labor savings.
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