Brake wire is an electrical conductor used in trailers and heavy-duty vehicles to supply current to electric braking systems.
Brake wire is a safety-critical conductor in transportation and industrial systems, delivering current to activate trailer and vehicle braking mechanisms. Typically built from stranded copper for flexibility and reliability, brake wires are insulated with durable materials such as PVC or cross-linked polyethylene (XLPE) to withstand heat, vibration, moisture, oils, and chemicals common in transportation environments. Color coding is often applied to simplify identification and ensure compliance with trailer manufacturing standards. Beyond trailers, brake wire is also used in equipment haulers and specialized industrial vehicles where reliable electric braking is essential for safety and performance.
Brake wire standards are typically defined by SAE (Society of Automotive Engineers) for automotive and trailer wiring. Additional performance and insulation requirements may also align with UL (Underwriters Laboratories) and ASTM (American Society for Testing and Materials) guidelines.
Brake wire emerged as electric braking systems became common in the mid-20th century, supplementing mechanical systems in trailers and trucks. The adoption of standardized trailer wiring harnesses established brake wire as a distinct conductor category in the transportation industry.