Rule 25 of 40 · Chapter IV — Conductors and Loads
Torque every connection to spec
Why this rule exists
Most failures in wiring are not in the wire; they are at the connections. A loose termination has resistance, resistance under current makes heat, heat oxidizes and loosens the joint further, and the runaway ends in a glowing connection that melts insulation and ignites its surroundings. Overtightening is just as bad; it nicks strands and stress-fractures the conductor. Manufacturers specify torque values because there is a right tightness that hand-feel rarely hits. A properly torqued connection stays cool and low-resistance for decades; a guessed one is a slow fault waiting for load.
In practice
Use a calibrated torque screwdriver or wrench and set terminations to the value marked on the device or in its instructions. Strip conductors to the correct length so bare copper is not exposed and insulation is not clamped under the screw. Seat stranded wire fully; do not let strands escape the terminal. Re-check torque on critical connections after the first thermal cycles if the manufacturer calls for it. Where you can, feel and look for heat discoloration on existing terminations during any service visit; a browned lug is a warning.
When it doesn't apply
Some terminals, especially older ones, have no published torque spec; follow good practice and the device listing. Push-in backstab connections bypass torque entirely and are a common failure point, so prefer the screw terminals. Aluminum connections need listed antioxidant and connectors rated for aluminum, and are torque-sensitive; treat them with extra care or leave them to someone experienced.