FR-1 is a flame rating designation that refers to the VW-1 vertical wire flame test.
FR-1 is a marking sometimes found on wire and cable products that indicates compliance with the VW-1 vertical flame test. Rather than representing a standalone test method, FR-1 functions as an alternate reference to the established VW-1 flame performance evaluation. This test measures a cable’s ability to resist flame propagation when exposed to a standardized ignition source in a controlled vertical configuration.
The VW-1 test is designed to assess whether insulation and jacket materials will self extinguish after exposure to flame and whether they limit flame spread along the length of a vertically oriented sample. During testing, a defined flame is applied for a specified duration and repeated in cycles. To pass, the cable must not exhibit excessive burning or allow flame to travel beyond prescribed limits. The test also evaluates whether flaming particles fall in a manner that could ignite surrounding materials.
In commercial and industrial environments, flame spread performance is an important safety consideration. Cables installed in equipment rooms, industrial control panels, and general purpose building spaces may be required to demonstrate compliance with recognized flame tests. An FR-1 or VW-1 marking provides documentation that the product has been evaluated against these criteria.
It is important to distinguish FR-1 or VW-1 from riser or plenum ratings. While VW-1 addresses flame propagation on an individual cable sample, riser and plenum classifications involve additional large scale fire tests that evaluate performance in specific building pathway types. As such, FR-1 is typically associated with general purpose applications rather than air handling or vertical shaft environments requiring higher tier fire performance classifications.
In specification documents and product markings, FR-1 serves as an indicator of basic flame resistance characteristics aligned with the VW-1 test method, supporting compliance within applicable commercial and industrial code frameworks.
Underwriters Laboratories