Flame Retardant Rating Requirements for Wire-Coated Silicone

The flame retardant rating requirements for wire-coated silicone depend primarily on the wire's application scenario and the mandatory standards of the corresponding country/region. Meanwhile, the inherent flame retardant properties of the silicone material itself-achieved by adding flame retardants such as aluminum hydroxide and magnesium hydroxide-must match the specified rating.

Below are the key requirements structured clearly:

1. Internationally Recognized Flame Retardant Rating Standard (UL 94 Standard)

This is the most commonly used flame retardancy test standard for wire insulation materials. The typical requirements for silicone coating layers are as follows:

UL 94 V-0This is the mainstream high-grade requirement in the wire industry, applicable to scenarios such as building wiring, industrial equipment, and automotive wiring harnesses.Test criteria: When undergoing vertical burning, the sample's combustion duration shall be ≤ 10 seconds; no molten drips shall ignite the cotton placed beneath; and the total combustion time for two consecutive tests shall be ≤ 50 seconds.

UL 94 V-1Suitable for non-critical circuits with relatively lower flame retardancy requirements.Test criteria: Combustion duration per test ≤ 30 seconds; total combustion time for two tests ≤ 250 seconds; no molten drips shall ignite the underlying cotton.

UL 94 V-2Rarely used for wire coating. Molten drips that ignite the cotton below are permitted, making it only suitable for extremely low-risk environments.

UL 94 5VA/5VBThese represent higher flame retardant ratings, applicable to high-voltage, high-temperature, and densely routed wires (e.g., power engineering, rail transit).During testing, samples must withstand more severe flame exposure without significant combustion spread.