In an attic with permanent stairs, how high must substantial guard strips be when protecting nonmetallic sheathed cable?

The requirement for guard strips in an attic to protect nonmetallic sheathed cable is based on safety considerations to prevent accidental damage to the wiring. Guard strips must be of a height that effectively prevents any objects or individuals from coming into contact with the cables, particularly in areas where movement occurs, such as attics accessed by permanent stairs. A height of 7 feet is specified as it ensures that typical climbing or reaching activities do not pose a risk to the integrity of the cables, effectively shielding them from equipment, tools, or any unintended impacts.

This height is aligned with safety codes and standards, emphasizing the importance of maintaining clearances that minimize the risk of hazards, thereby promoting safe working practices in attic spaces. The codes recognize 7 feet as an effective barrier height that balances accessibility and protection, ensuring that the cables remain undisturbed and functional.