: Cracks in the rubber or plastic coating of wires (often caused by aging, heat, or "motion fatigue") expose copper conductors. This creates a path for electricity to jump, causing short circuits.
A physical crack in a plastic outlet, switch plate, or wire insulation is rarely just cosmetic. These components serve as the primary barrier between you and live current. see electrical crack
There are several key factors that contribute to the formation of electrical cracks: : Cracks in the rubber or plastic coating