How frequently must manufactured wiring systems constructed with type MC cable be supported and secured?

Manufactured wiring systems that use type MC (metal-clad) cable require proper support and securing to ensure safety and compliance with electrical codes. The National Electrical Code (NEC) specifies that type MC cable must be supported and secured at intervals not exceeding 6 feet. This requirement is in place to prevent sagging, stress on the connections, and potential physical damage to the cable over time.

Maintaining this spacing ensures that the cable remains stable and protected, which is particularly important in environments where it might be subject to movement or impact. Additionally, this regulation emphasizes the importance of proper installation practices to enhance the overall safety of electrical systems.

The other distances provided do not align with the NEC guidelines for supporting and securing type MC cable, which is strictly set at 6 feet. Thus, the answer is based on established safety standards that govern electrical installations.