High voltage is a design regime, not a gauge size: once system voltage climbs past the low-voltage world (industry practice places the boundary around 60V DC / 30V AC), every harness element — cable, connector, termination, routing, test — changes its requirements. This guide covers the design essentials for HV harnesses in vehicles, energy storage, industrial equipment and power systems.
HV Cable Construction
HV cable differs from LV cable in four engineered respects: insulation — thick-wall, high-dielectric-strength compounds (XLPE, silicone, fluoropolymer classes) rated to the system voltage with standards-mandated margins; shielding — semiconductive and metallic shield layers that contain the field and provide a defined fault-return path, terminated 360-degree at both ends (our shielded cable guide covers the termination mechanics); conductor — sized for current and thermal duty, with aluminum taking range-weight-critical automotive roles (our aluminum wire analysis covers the termination engineering); jacket — orange by convention in automotive and storage systems, abrasion- and fluid-resistant for the zone.
Termination: Where HV Harnesses Are Made or Broken
HV terminations concentrate three risks: thermal (a marginal crimp in a 200A circuit is a heat source — crimp resistance is specified, monitored and measured, per our crimp quality discipline), dielectric (insufficient creepage/clearance or damaged insulation creates flashover paths — connector selection respects both, and assembly protects insulation integrity through stripping and routing), and mechanical (high-current lugs and contacts carry real clamping loads — torque and insertion verification are process items, not optional checks). The termination document on an HV harness drawing is therefore longer than the drawing itself, and rightly so.
Safety Design: The HVIL Concept
High-voltage systems protect people through design, and the harness is part of the protection: interlock loops (HVIL) — low-voltage circuits threaded through HV connectors that break the loop when a connector separates, de-energizing the circuit before hands reach HV metal; touch-proof connectors — contacts that cannot be touched when unmated; labeling — HV warning marks per the application standard; sealed systems — HV connectors sealed to their zone's IP targets because water changes dielectric behavior unpredictably. Our EV harness guide shows the automotive implementation of this stack.
Routing and Environmental Rules
HV routing respects: separation from LV signal looms (EMC and safety both — a shield breach that couples HV into a control circuit is a systems failure), abrasion protection at every pass-through (grommets, convolute, standoff clips), bend radius discipline (insulation and shield integrity live here), and thermal zoning (distance from heat sources or rated insulation for the exposure).
Testing at HV Levels
HV harness test goes beyond continuity: hipot (dielectric withstand) at specified levels verifies insulation, insulation-resistance measurement quantifies it, shield continuity verifies the fault-return path, and partial-discharge testing applies in the most demanding applications. Every HV harness is tested — the category has no sampling-only tiers.
Kaweei HV Harness Manufacturing
Kaweei manufactures high-voltage harness assemblies for EV, energy storage and industrial power applications — shielded HV constructions, interlock-equipped assemblies, full hipot and IR test documentation — from our Dongguan facility. Contact our engineering team with your system voltage and application; our HV connector guide covers the mating hardware.