Heating at Electrical Contacts: Characterizing the Effects of Torque, Contact Area, and Movement on the Temperature of Residential Receptacles

摘要

Testing was performed using 120 volt, 15-amp receptacles and copper wire to determine the effect of torque and wire contact area on temperature elevation at receptacle screw terminals. Torque was varied on both the hot and neutral terminals from 0 to 12 in-lbs, and the apparent wire contact at the screw terminal was varied by 1/8″ and 5/8″. There was no significant difference in temperature when changing apparent wire contact. Increased temperatures were observed with reduced torque, however, they were not significant enough to initiate a glowing connection, nor high enough to cause rapid oxidation. Further testing showed that movement of a loose connection was necessary to cause significantly high temperature changes, arcing and sparking, rapid oxidation, and in some cases, glowing connections.