What is the maximum length of festoon lighting conductors before they must be supported by messenger wire?

The maximum length of festoon lighting conductors that can be used before requiring support by messenger wire is indeed 40 feet. This standard is in place to ensure safety and structural integrity, as longer lengths without proper support can lead to sagging or damage to the conductor, which could result in electrical hazards or failures. The use of a messenger wire allows for the secure and stable support of the conductors, preventing excessive tension and ensuring that the lighting remains properly positioned. This guideline helps in maintaining compliance with electrical codes and industry best practices, which prioritize the safety of installations involving temporary or portable lighting.