The geometry of the AFL universal groove represents an engineering achievement: on an optimum shape for both electrical and mechanical efficiency for a range of conductor sizes. This unique groove shape is used for catalog series 390,480, and 580.
Groove for 390 Series, used for service drops, and 480 Series, used for full load connections, are protected with a film of grease.
Aluminum bolts used in parallel groove clamps have an alumilite 205 finish and a thin coating of inhibitor compound. The hard finish and lubrication reduce thread friction and provide greater clamping force on the conductor for a given torque.
These bolts will not seize. Benefits of aluminum bolts also include equalized expansion and contraction and contraction with temperature changes and favorable modulus of elasticity for “spring follow-up.”