How many joints between supports are permissible for vertical runs of metal wireways?

In the context of electrical installations, particularly regarding vertical runs of metal wireways, it is essential to adhere to specific guidelines to ensure safety and functionality. The correct answer indicates that only one joint between supports is permissible. This restriction is likely put in place to maintain structural integrity and reduce the potential for electrical faults.

Allowing a single joint minimizes the risk of connection failures, which can occur if multiple joints are used. Each joint introduces a potential point of failure due to thermal expansion, vibrations, and mechanical stress. Therefore, limiting the number of joints helps to ensure a more reliable and stable installation.

Additionally, regulations and standards, such as those set forth by the National Electrical Code (NEC), dictate these parameters to promote safety in electrical systems. The design intention is to create a clean and efficient pathway for conductors while minimizing the complexity and risk associated with multiple connections. Thus, understanding and adhering to this guideline is crucial for compliance and safety in electrical practices.