You're holding a locknut on one side of an electrical box while trying to tighten the nut on the other — and the locknut spins instead of biting, leaving you with a loose connection that will work its way free or create a fire hazard. Loose locknuts are one of the most common electrical call-backs on panel work done without the right hardware on hand. 1/2-in steel locknuts with zinc plating — zinc-plated steel bites into the box or enclosure surface and locks in place without spinning, unlike unplated or poorly machined locknuts that skate across the surface. The 4-pack covers most residential panel and box jobs without running short. 1/2-in size fits the most common residential knockout. Standard in the electrical hardware inventory of residential electricians across northeast Nebras Stocked at Crofton Lumber and Akron Lumber.