Plastic Enclosures Flammability

UL 94 Flammability Ratings

Plastic Enclosures are rated for flammability using the UL 94 standard. There are 6 levels of certification that can be obtained as follows: –

• 5VA (Surface Burn) – Burning stops within 60 seconds after 5 applications of 5 seconds each of a flame (larger than used in vertical burn testing) to a test bar. Test specimens may not have a burn-through (no hole should be seen).
• 5VB (Surface Burn) – Burning stops within 60 seconds after 5 applications of 5 seconds each of a flame (larger than used in vertical burn testing) to a test bar. Test specimens may have a burn-through (a hole).
• V-0 (Vertical Burn) – Burning stops within 10 seconds after two applications of 10 seconds each of a flame to a test bar. No flaming drips are allowed.
• V-1 (Vertical Burn) – Burning stops within 60 seconds after two applications of 10 seconds each of a flame to a test bar. No flaming drips are allowed.
• V-2 (Vertical Burn) – Burning stops within 60 seconds after two applications of 10 seconds each of a flame to a test bar. Flaming drips are allowed.
• H-B (Horizontal Burn) – Slow horizontal burning on a 3mm thick specimen with a burning rate is less than 3”/min or stops before the 5” mark. H-B rated materials are considered “self-extinguishing”. This is the lowest (least flame retardant UL94 rating)