What is UL746C F1 Plastic Rating? Difference Between F1 and F2 Weathering Grade

Many electrical, lighting and smart meter engineers will encounter UL746C F1 when selecting outdoor plastic resins. UL746C is the standard for polymeric materials used in electrical equipment, while F1 and F2 are outdoor weathering classifications defined under UL746C.

UL746C F1 rating means the plastic passes both UV aging test and water exposure / immersion test. It resists yellowing, cracking and performance degradation under long-term outdoor sunlight and rain exposure. F2 grade only passes one of the two tests, with weaker weather resistance and is only suitable for partial semi-outdoor applications.

In short, for enclosures and lenses permanently exposed outdoors for North American market, materials are usually required to meet UL746C F1.

Modified polycarbonate (PC) is the most common resin meeting UL746C F1. Formulated with UV stabilizers, it balances flame retardancy, impact resistance and outdoor durability with UL yellow card for end product UL certification. Ordinary unmodified PC has no F1 rating; it quickly turns yellow and brittle under long outdoor exposure and cannot pass North American customer certification audit.

When exporting electrical products to North America, the material UL yellow card must clearly state UL746C F1 for the final product UL certification. We supply UL746C F1 certified PC resin with full data sheets and UL yellow cards for OEM sampling and product certification.

Selecting UL746C F1 plastics at the early stage of outdoor electrical product design helps avoid rework in product certification and saves lead time and certification cost.