Automotive & Transport Wire Harness

Vehicles are a hostile place for a conductor. There is continuous vibration, a temperature gradient of more than a hundred degrees across the same loom, and water that finds every unsealed joint. The harnesses in this group are built around those three facts: tinned or well-protected conductors, sealed terminations, and a bill of materials that splits the under-bonnet route from the cabin route instead of defaulting the whole vehicle to one wire.

Electrification adds a fourth problem on top of the first three. A traction circuit at 1000 V DC needs a conductor rated for the voltage, a shield that is terminated deliberately, and creepage that survives the pack dielectric test. Those assemblies sit in this group alongside the conventional 12 and 24 V looms, because in practice they share a vehicle and often share a connector family.

Zone by zone, the wire changes. Under the bonnet, where ambient plus radiated heat is the governing stress, the group draws on 125 °C cross-linked lines such as the UL3271 and UL3272 motor-lead wires; the cabin side of the same loom is normally 105 °C PVC or SRPVC in UL1007, UL1015 or UL10002, which is cheaper, strips cleanly and takes a crimp well. Running one wire across the whole vehicle because it is easier to order is the most common cost mistake we see in a vehicle bill of materials.

The 1000 V DC sections use UL10183, a 1000 V AC and 1200 V DC single conductor with XL-PVC insulation at 105 °C, or one of the cross-linked traction styles where the pack vendor specifies a higher temperature. Sense and interlock circuits are deliberately kept on a different wire from the power conductors, both because the gauge is different and because an interlock that shares a bundle with a 400 A conductor is an interlock that will eventually read the wrong thing.

Termination is where a vehicle loom is won or lost. Crimps are made with the tool that matches the terminal series, on tinned copper where the route is damp, and every splice is sealed with adhesive-lined heat-shrink rather than tape. Branches are fixed to a breakout length taken from the drawing, so the loom does not pull against a connector when the vehicle flexes. Marine and off-road variants use the same construction with a higher proportion of tinned conductor and sealed ring terminals.