Hand-Grip Torque for Circular Electrical Connectors: The Effect of Obstructions

The hand grips of 18 male and 16 female subjects were studied to determine the maximum, clockwise static torque that could be applied to circular electrical connectors under six defined levels of interference and four conditions of interference (types of obstruction) with and without work gloves. The diameters of connectors tested were 0.9, 1.5 and 2.0 in., respectively. Torque strength and required separation were found to be a function of level of interference, condition of interference, connector size, and glove usage. Interference from an adjacent surface to the right or below the grasped connector was less severe than interference from adjacent connectors to the left and right. The greatest interference occurred when adjacent connectors were located to the right, left, above and below the grasped connector. Large connectors permitted greater torque and required less surface-to-surface clearance than small connectors. The use of work gloves increased torque strength slightly but required much larger clearances. Limitations in hand torque strength and required clearances for exertions should be taken into account as ergonomic guidelines for maintainability.