What is UL 977?

UL 977 is a technical standard developed by Underwriters Laboratories (UL) to address the safety and performance requirements for nonmetallic raceways used in electrical distribution systems. This standard applies to raceway systems intended for use in commercial, industrial, and residential construction.

The Purpose of UL 977

The primary purpose of UL 977 is to ensure the safe installation and use of nonmetallic raceways. It sets forth specifications and testing procedures that evaluate the flame resistance, impact resistance, mechanical strength, and environmental performance of these raceway systems.

Key Requirements of UL 977

UL 977 outlines specific requirements for various aspects of nonmetallic raceways, including material properties, dimensions and tolerances, markings, and performance testing. Some key requirements include:

Flame Resistance: The raceway system should have a certain level of resistance to flame propagation to minimize the risk of fire spreading.

Impact Resistance: The raceway system should be able to withstand a certain amount of external force or impact without sustaining damage.

Mechanical Strength: The raceway system should possess sufficient strength and rigidity to maintain its structural integrity under normal operating conditions.

Environmental Performance: The raceway system should be resistant to environmental factors such as moisture, chemicals, and ultraviolet (UV) radiation.

Compliance and Certification

To demonstrate compliance with UL 977, manufacturers must submit their nonmetallic raceway products to independent testing laboratories recognized by UL. These laboratories conduct rigorous tests and evaluations according to the requirements specified in UL 977. If the raceway products pass all the necessary tests, they can receive UL certification, which indicates that they meet the safety and performance standards outlined in the standard.