The UL 94 flammability rating is a standard by the global safety certification company Underwriters Laboratories (UL) that classifies plastics according to how they burn in various orientations and thicknesses under controlled laboratory conditions. This standard helps manufacturers assess the flammability characteristics of their plastic materials and products. Here are the critical details about the UL 94 flammability rating:

•  The test evaluates the burning behavior of plastic materials. Samples are typically subjected to a small flame or radiant heat source for a specified period. The behavior of the material, including whether it ignites, how long it burns, how much it burns, and whether flaming drips occur, is recorded.
• UL 94 ratings include several classification levels based on how the material burns:
• V-0, V-1, and V-2: For vertical burn tests. V-0 is the highest (best) rating, where burning stops within 10 seconds on a vertical specimen; drips of particles are allowed as long as they are not inflamed. V-1 is similar but allows for up to 30 seconds of burning. V-2 also has a 30-second limit but allows flaming drips.
• HB: Horizontal burn; slow burning on a horizontal specimen.
• 5VB and 5VA: Burn tests with a higher burning intensity than the V rating. They are done on both bar and plaque. 5VA is the highest rating, where the specimen must not burn (or have holes) after five applications of the test flame within 60 seconds with no drops of plastic. 5VB is when the plastic might have a burn-through (holes) but no plastic drops.

Cables Under UL 94 Test

The UL 94 flammability standard itself directly applies to the testing and classification of plastics used in components and parts, including those in electrical devices and equipment. However, for cables and wires specifically, there are other UL standards that often incorporate UL 94 criteria as part of broader performance evaluations. These include:

1. UL 1581: This standard covers testing for the electrical and physical properties of cables, including flame tests that assess how cables hinder the spread of fire. These tests might reference UL 94 ratings in terms of the plastic materials used in cable insulation and jacketing.
2. UL 2556: Another standard that includes flame tests for wire and cable, similar to UL 1581, focuses on how cables perform in fire conditions, possibly using criteria from UL 94 for material flammability.
3. UL 758: Applies to appliance wiring material (AWM), which might include requirements related to the flammability of insulation materials, potentially influenced by UL 94 classifications.

Cables are not "approved" by the UL 94 test directly, but the plastics used in their insulation and sheathing might be UL 94 rated. When a cable product claims UL 94 compliance, it typically refers to the flammability rating of the plastic components rather than the entire cable. When selecting cables for specific applications, particularly where safety and fire resistance are critical, it's important to look for UL ratings that indicate compliance with the applicable standards for that specific type of cable.

Insulations Covered by UL94

When discussing cables where the plastics are approved based on the UL 94 flammability test, it's useful to consider the types of plastics typically used for insulation and jacketing in cables that require high flame retardancy. Here are some examples of such plastics and the cable types where they might be found:

1. Polyvinyl Chloride (PVC): Widely used in various cable types due to its good flame retardant properties, flexibility, and durability. PVC can achieve UL 94 V-0 or V-1 ratings depending on its formulation. 
2. Thermoplastic Polyurethane (TPU): Known for its excellent abrasion resistance and flexibility, TPU can be formulated to meet high UL 94 ratings, such as V-0.
3. Polyethylene (PE): Typically used for its electrical insulation properties. When fire-retardant additives are mixed, PE can achieve a UL 94 rating, often used in telecommunication and coaxial cables.
4. Fluoropolymers (such as PTFE, FEP): These materials have inherently high resistance to flames and can achieve V-0 ratings. They are used in high-temperature cables.
5. Polypropylene (PP): Known for its chemical resistance and electrical insulating properties, it is often used in automotive and consumer electronics. Higher ratings like V-0 or V-2 are possible for PP with the addition of flame retardant additives.
6. Thermoplastic Polyurethane (TPU): TPU is valued for its flexibility and durability and is used in environments requiring robust mechanical properties and flame resistance. TPU can achieve higher ratings like V-0 or V-1, particularly when formulated with flame-retardant additives.
7. Fluoropolymers (e.g., PTFE, FEP): High-performance plastics used in applications requiring resistance to high temperatures and chemicals, typically achieving high UL 94 ratings. V-0 is possible for this material.
8. Polystyrene (PS) and Acrylonitrile Butadiene Styrene (ABS): These insulations are common in consumer electronics and computer equipment; they can achieve V-0 or V-1 ratings.
9. Polyamide (Nylon): Nylon is used in various electronic components and connectors due to its toughness and good insulation properties. Nylon can typically achieve V-2 or V-1 ratings.
10. Polycarbonate (PC): PC is strong and transparent and can reach V2 or V0.

Nassau National Cable offers a wide range of cables with insulations passing the UL 94 rating.