What does your wire harness testing service include?

Our wire harness testing service includes 100% continuity and pinout verification as the baseline, with optional resistance measurement, hipot dielectric withstand testing, insulation resistance, pull-force checks, visual workmanship inspection, and customer-specific functional fixtures. The exact test matrix is defined from your drawing, BOM, and control plan before production starts, so every lot uses the same acceptance criteria.

I need 200 custom harnesses for an industrial machine. Is 100% testing necessary?

Yes, 100% electrical testing is the safer choice for a 200-unit industrial harness order because one swapped pin can stop machine commissioning or damage a connected controller. Sampling can miss low-frequency errors in multi-branch harnesses. For 200 pieces, the test fixture cost is usually justified by faster receiving inspection, cleaner installation, and documented pass/fail records for each production lot.

Can you provide hipot testing for high-voltage cable assemblies?

Yes, we support hipot testing for high-voltage cable assemblies when the drawing or customer test plan defines the voltage, dwell time, leakage limit, and test points. Common harness programs use 500 VDC to 3000 VDC, while higher requirements are reviewed case by case. Hipot is especially useful for EV battery cables, sealed connectors, and assemblies where insulation failure creates a safety risk.

How do you document cable assembly testing results?

Cable assembly testing documentation can include a lot-level test summary, certificate of conformance, inspection checklist, crimp audit record, and unit-level pass/fail data when required. For regulated or automotive-style programs, we can align records with the traveler, part number, revision, date code, and operator or fixture identification. Tell us the documentation package during RFQ so it is included in the quote.

Should I choose continuity testing, insulation resistance, or functional testing?

Choose continuity testing for all harnesses, add insulation resistance or hipot when voltage, sealing, or safety risk is meaningful, and add functional testing when the harness interacts with sensors, relays, control boxes, or powered modules. A simple two-wire lead may only need continuity. A 40-circuit automotive harness with sealed connectors should include continuity, polarity, visual inspection, and selected dielectric checks.

My project timeline is 6 weeks from drawing release to delivery. Can testing fit that schedule?

Yes, a 6-week schedule is realistic if the drawing, BOM, connector availability, and test criteria are complete at RFQ. Prototype builds can often ship in 7-10 business days, while production lead time depends on component sourcing and fixture complexity. The fastest route is to send the pinout table, acceptable resistance limits, hipot requirements, and any customer inspection form with the first quote request.

Do you test to IPC/WHMA-A-620 Class 3?

Class 3 workmanship inspection is available for high-reliability programs, but it must be specified before quoting because it changes inspection time, operator qualification expectations, and acceptance criteria. Class 2 is the standard production reference for most commercial and industrial harnesses. Class 3 is usually reserved for aerospace, defense, medical, and safety-critical applications where field failure carries elevated risk.

100% Electrical Verification

Wire Harness Testing Service forProduction-Ready Cable Assemblies

Every tested harness leaves with a defined pass/fail record: continuity, polarity, hipot, insulation resistance, crimp pull-force, and IPC/WHMA-A-620 workmanship checks matched to your drawing instead of generic sampling.

100%

Electrical Test

500-3000V

Common Hipot Range

30 AWG-4/0

Wire Gauge Range

Class 2/3

A-620 Inspection

Request a Test Plan Quote

Upload drawings, pinout table, BOM, or inspection criteria. Engineering reviews test scope before pricing.

Documented Records

Lot-level and unit-level test records available when specified.

Certified Systems

ISO 9001:2015 and IATF 16949:2016 quality systems in the factory network.

Early Risk Flags

Test criteria reviewed before quote to prevent schedule surprises.

Production Release

Testing supports prototypes, pilot lots, and recurring OEM releases.

Testing Is the Control Gate Between a Working Sample and a Reliable Production Harness

Wire harness testing service buyers usually have one concern: they need proof that the harness will not stop their production line after receiving inspection. WellPCB already builds custom assemblies under ISO 9001:2015 and IATF 16949:2016 quality systems, with 100% electrical testing referenced across our factory wiring harness and custom cable assembly processes.

The important difference is scope. A simple continuity test proves every conductor reaches the expected pin. It does not prove insulation margin, crimp strength, connector latch engagement, seal integrity, or functional behavior under load. We define the test matrix from the harness drawing so each risk gets the right verification method.

Our best fit is production-bound custom harness work: prototypes heading into NPI, OEM cable programs, sealed assemblies, automotive harnesses, medical device cable sets, battery cables, and multi-branch industrial harnesses. We are not a standalone certification lab and we do not issue safety approval for finished equipment.

Wire harness electrical testing and inspection equipment

Wire Harness Test Methods We Support

Each method answers a different failure question. The correct test plan depends on voltage, connector style, environment, harness complexity, and customer documentation requirements.

Continuity and Pinout Verification

Every circuit is checked against the approved net list so opens, shorts, swapped pins, and missing conductors are caught before shipment. This is the baseline test for every custom wire harness testing service order, not a sample-only inspection.

100% circuit verification
Open and short detection
Polarity and pinout confirmation
Digital pass/fail records

Hi-Pot Dielectric Withstand Testing

High-voltage harnesses, sealed assemblies, and safety-critical programs can add hipot testing to verify insulation integrity between conductors or conductor-to-shield paths. Test voltage and dwell time are set from your drawing or control plan.

Common range: 500 VDC to 3000 VDC
Higher test plans reviewed case by case
Conductor-to-conductor and conductor-to-shield
Failure isolation before rework

Insulation Resistance Measurement

Insulation resistance testing identifies moisture intrusion, jacket damage, contamination, and marginal separation before a harness reaches the customer line. We typically use this test for waterproof, medical, and high-voltage cable assemblies.

500 VDC insulation checks when specified
Pass criteria from customer drawing
Useful after overmolding or potting
Records available by lot or unit

Crimp Pull-Force and Crimp Height Checks

Electrical continuity alone does not prove a terminal crimp will survive vibration, heat, and service handling. We combine periodic crimp-height inspection with pull-force checks based on terminal, wire gauge, and workmanship class.

Pull-force checks by wire gauge
Crimp height audit records
Terminal applicator setup review
IPC/WHMA-A-620 aligned inspection

Visual Workmanship Inspection

Trained inspectors check connector seating, terminal lock engagement, wire dress, branch breakout, heat-shrink coverage, label accuracy, and jacket damage. Visual inspection catches assembly defects that automated electrical tests cannot see.

Connector latch verification
Terminal retention review
Label and revision check
Class 2 standard, Class 3 available

Functional and Customer-Specific Test Fixtures

When a harness interfaces with sensors, relays, control boxes, or battery modules, we can build a customer-specific fixture that checks more than continuity. Fixture scope is defined during drawing review so the quote reflects the actual test burden.

Custom fixture planning
Sensor and load simulation options
Customer test plan support
Fixture validation before production

Testing Scope, Limits, and Buyer Inputs

These specifications are drawn from existing WellPCB wire harness production capabilities and are used to define the quotation boundary.

Supported Products	Wire harnesses, cable assemblies, battery cables, overmolded cables, and box-build harness sets
Electrical Test Coverage	Continuity, shorts, opens, polarity, resistance, hipot, and insulation resistance where specified
Workmanship Reference	IPC/WHMA-A-620 Class 2 standard; Class 3 available for critical programs
Wire Gauge Range	30 AWG to 4/0 AWG, based on existing factory production capability
Conductor Count	Single-conductor leads through 240+ conductor harness assemblies
Test Documentation	Pass/fail report, lot traveler, inspection checklist, and unit-level records when required
Prototype Timing	7-10 business day sample builds when components and tooling are available
Production Range	1-piece validation builds through recurring production lots and 100K+ monthly programs
File Inputs	PDF drawing, pinout table, BOM, test specification, sample harness, or customer control plan
Out of Scope	We do not certify third-party products, repair field returns as a lab service, or write safety standards for your end product

Practical selection rule

If a harness has fewer than 10 circuits, low voltage, and non-critical use, continuity and visual inspection may be enough. If the harness carries safety-related power, uses sealed connectors, includes more than 40 circuits, or ships into automotive, medical, robotics, or outdoor equipment, add insulation resistance, selected hipot, crimp audits, and formal records.

How the Test Plan Moves From Drawing to Shipment

A wire harness test plan works only when it is defined before production. We lock the test fixture, acceptance limits, and document package before the lot begins.

Drawing and Test Requirement Review

We review the harness drawing, pinout table, BOM, revision level, and any customer test plan. Missing pass/fail limits are flagged before quoting so the production floor does not guess.

Test Matrix and Fixture Planning

Engineering maps each circuit to the required test method: continuity only, continuity plus resistance, hipot, insulation resistance, pull-force audit, or functional fixture testing.

First Article and Setup Validation

The first build verifies wire routing, connector orientation, terminal retention, label placement, and electrical test fixture setup before a full lot is released.

In-Process Inspection

Operators check cut length, strip length, crimp height, terminal lock, and branch routing during production. Defects are contained before they become finished harness inventory.

100% Final Electrical Test

Every completed harness is tested against the approved setup. Failed units are isolated, corrected under controlled rework, and retested before packaging.

Documentation and Release

Finished lots ship with agreed documentation: test summary, certificate of conformance, inspection checklist, lot traceability, or unit-level records for regulated programs.

Hommer Zhao on Test Planning

"The expensive testing mistake is not under-testing or over-testing. It is undefined testing. If the drawing says '100% test' but does not define pins, voltage, dwell time, resistance limit, and record format, the factory and customer are not measuring the same thing."

Hommer Zhao

Founder & Technical Director, WellPCB

Applications Where Testing Pays for Itself

Testing intensity should match the cost of failure. A desk accessory and an EV battery harness should not use the same inspection plan.

Automotive and EV Harnesses

IATF 16949 programs use testing to prevent pinout errors, crimp escapes, and dielectric failures in battery, sensor, ADAS, and vehicle-control harnesses.

View related application

Medical Device Cable Assemblies

Medical equipment harnesses often need documented continuity, insulation, and workmanship checks because failures can affect diagnostic uptime or patient monitoring accuracy.

View related application

Industrial Automation Systems

PLC, servo, robotics, and control cabinet harnesses benefit from 100% pinout testing because a single swapped conductor can stop a commissioning schedule.

View related application

Waterproof and Outdoor Cable Assemblies

Sealed harnesses can add insulation resistance, hipot, and post-seal visual inspection to catch moisture paths before field installation.

View related application

Reference Standards and Stable Public Resources

We avoid linking to standards storefronts that block crawlers. These stable references explain the organizations and concepts behind the test plan language.

IPC and Cable Assembly Workmanship

IPC is the electronics industry association behind widely used acceptability standards for cable and wire harness workmanship.

Open reference

Dielectric Withstand Testing

Dielectric withstand testing explains why hipot checks are used to verify insulation strength in electrical products.

Open reference

Cable Harness Terminology

A cable harness is a routed assembly of wires, terminals, connectors, and protective coverings used to transmit power or signals.

Open reference

Wire Harness Testing Service FAQ

Answers for buyers planning inspection scope, documentation, lead time, and acceptance criteria.

Related Wire Harness Services

Testing is most effective when it is connected to the build process, documentation package, and production release plan.

Factory Wiring Harness

Production builds with fixture-board assembly, automated crimping, and 100% electrical test records.

Learn more

Prototype Wire Harness

Validate test points, pinouts, and first-article criteria before releasing a production harness.

Learn more

Waterproof Wire Harness

Sealed assemblies where insulation resistance and dielectric testing help verify environmental protection.

Learn more

OEM Cable Assembly

Contract production programs that need revision control, recurring releases, and formal inspection records.

Learn more

Need a Harness Test Plan Before Production Release?

Send your drawing, pinout table, BOM, target quantity, and required documentation. We will review test coverage, fixture needs, risk points, and return a quote for tested wire harness production.