Where IMC enters a box, fitting, or other enclosure, what shall be provided to protect the wire from abrasion unless the design affords equivalent protection?

• A. a bushing
• B. a clamp
• C. a gasket
• D. a connector

Answer: (A)

Protecting conductors from abrasion at entry points is important because the sharp edges of a knockout or opening can nick insulation as IMC passes into a box or enclosure. A bushing provides a smooth, rounded surface that shields the conductor insulation from those edges, preventing damage and potential short circuits or insulation failure. If the enclosure or fitting already offers equivalent protection (built-in protection), an extra bushing isn’t needed, but in typical installations a bushing is the required means of protection. A clamp, gasket, or connector alone doesn’t provide the necessary protection against edge abrasion in the entry opening.