What is the requirement for cable clamps in boxes?

The requirement for cable clamps in boxes, as outlined in the National Electrical Code (NEC), is that clamps must securely hold conductors without damaging insulation. This is crucial because properly secured conductors help prevent physical damage and potential electrical hazards. When clamps hold conductors securely, it minimizes the risk of movement that can lead to wear on insulation over time, which could cause short circuits or electrical failures.

In addition to maintaining the integrity of the electrical system, ensuring that the clamps are secure helps in maintaining a safe work environment, as loose conductors can lead to entanglements or accidental disconnections.

The other options do not align with NEC requirements. Clamps do not have to be adjustable (the first option), nor can they be loose (the third option), as this would compromise safety and protection. Lastly, while attachment points can enhance security, there is no specific NEC requirement for clamps to always have a minimum of three attachment points. The focus is on security and insulation protection, making the correct choice essential for safe installation practices.