Where Type NM cable passes through factory or field openings in metal members, how should it be protected?

When Type NM cable passes through openings in metal members, it is essential to protect the cable to prevent damage from sharp edges or burrs that could compromise the insulation and overall integrity of the cable. The National Electrical Code specifies the use of listed bushings or listed grommets as appropriate methods for providing this protection.

Listed bushings and grommets are designed specifically for the electrical industry and have been tested for effectiveness in safeguarding cables as they transition through potentially damaging spaces. Their use ensures that the cable's insulation remains intact, thus reducing the risk of short circuits or electrical failure that could result from abrasion against the edges of the metal openings.

The inclusion of both bushings and grommets as acceptable options emphasizes the importance of using recognized protective devices in compliance with safety standards. This choice reflects a best practice within the electrical industry, ensuring that installations remain safe and reliable while adhering to NEC requirements.