Low-Voltage Automotive Wire Selection and Classification Guide

This document provides a comprehensive guide on the classification and selection of low-voltage wires for automotive applications. Wires are categorized into four series based on standards: national (GB/T8139), Japanese (JASO D608, D609, D611), German (ISO 6722), and American (SAE J1128, J1678, US-CAR-21). The wire selection process involves calculating the operating current of electrical equipment using rated power and voltage parameters, then choosing wire type and diameter. Wire type selection considers temperature resistance (8 levels per ISO 6722), vibration, wear, corrosion, and moisture resistance. For signal circuits, twisted pair or shielded wires are recommended. Wire diameter is initially chosen from supplier tables ensuring rated current capacity exceeds load, followed by voltage drop checks for long loops. The document also details wire types by standard and use, including ordinary wires, twisted pairs (e.g., for CAN bus with 120Ω impedance), and shielded wires for analog signals. Proper wire selection ensures safety, reliability, and lightweight design in automotive wiring harnesses.