Key Takeaways (Executive Summary)
- The Baseline: Every professional cable assembly must undergo 100% Continuity Testing to ensure no wires are crossed (mis-pinned) or broken (open circuit).
- Safety First: For cables carrying power (>50V), Hipot (High Potential) testing is mandatory to check for insulation breakdown and potential arc faults.
- Destructive Testing: Pull Force Testing is a mechanical check performed on crimps during setup. It is destructive, so it is done on samples, not the final product.
- The "Golden Sample": Always require a First Article Inspection (FAI) report to validate that the manufacturing process matches the print before mass production begins.
Trust, But Verify
In manufacturing, there is a saying: "You cannot inspect quality into a product; you have to build it in."
However, in the world of wire harnesses, verification is the only firewall between a safe product and a recall. A technician might crimp 99 terminals perfectly, but if the 100th terminal has a stray strand of copper touching the signal line, the entire system fails.
To prevent this, we employ a multi-layered testing protocol. It’s not just about "does it work?"; it’s about "will it last?"
Here are the standard tests you should expect your manufacturer to perform.
1. Continuity Testing (The Logic Check)
This is the standard, non-negotiable test for every single unit (100% Testing). We use automated testers (like Cirris or CableEye systems) to verify the internal map of the cable.
What it Checks:
- Opens: Is the wire broken internally?
- Shorts: Are two wires accidentally touching?
- Mis-wires: Did the operator swap Pin 1 and Pin 2?
- How it works: The tester sends a low voltage (5V) signal down every pin and ensures it arrives at the correct destination. If the resistance is too high (e.g., >2 Ohms), it fails.
2. Hipot Testing (The Safety Check)
Hipot (High Potential) testing, also known as Dielectric Withstand, is a stress test for the insulation. It is critical for cables carrying dangerous voltages (medical, EV, industrial).
The Concept: Just because two wires aren't touching doesn't mean they are safe. If the insulation is thin or nicked, high voltage can "jump" (arc) between them.
- The Test: We apply a massive over-voltage (e.g., 500V DC or 1000V AC) between the conductors for a few milliseconds.
- The Pass Criteria: If any current leaks through the insulation (Leakage Current), the cable fails. This ensures the customer won't get shocked.
Comparison Table: Continuity vs. Hipot
Do you need both?
|
Feature |
Continuity Test |
Hipot Test (Dielectric) |
|---|---|---|
|
Voltage Used |
Low (5V - 12V) |
High (500V - 1500V+) |
|
Goal |
Verify Logic / Connection |
Verify Safety / Insulation |
|
Detects |
Broken wires, Crossed pins |
Nicked insulation, Arcing risk |
|
Standard |
Mandatory for all cables |
Mandatory for Power/HV cables |
|
Cost |
Included in assembly cost |
Adds setup time/cost |
3. Pull Force Testing (The Mechanical Check)
Crimp quality is invisible to the naked eye. A crimp can look perfect but fall off if you tug on it.
Pull Testing is a Destructive Test. We cannot do it on the finished cable (because it breaks the part!).
- Process: Before the shift begins, the operator crimps 5 sample terminals.
- Action: We put them in a Pull Tester machine that stretches them until they snap.
- Validation: If the wire breaks before the crimp slips, the crimp is good. If the wire pulls out of the crimp, the pressure is too low. We re-calibrate the press and re-test.
Standard: We follow UL 486A pull force requirements.
- 18 AWG Wire: Must hold 20 lbs (89N).
- 12 AWG Wire: Must hold 70 lbs (311N).
4. Advanced Testing: VSWR (RF Cables)
For coaxial cables (antennas, Wi-Fi, GPS), simple continuity isn't enough. We need to know how well the signal travels.
We use a Network Analyzer to measure VSWR (Voltage Standing Wave Ratio).
- The Concept: If the connector is soldered poorly, the radio signal bounces back (reflects) like an echo.
- The Goal: We want a VSWR close to 1:1 (No reflection). A high VSWR means the cable is absorbing the signal, and your range will suffer.
Frequently Asked Questions (FAQ)
Q: Do you test 100% of the cables or just a sample? A: For Continuity and Short testing, we test 100% of cables. We never ship a "dead" cable. For destructive tests (Pull Test) or advanced RF validation, we typically test based on an AQL (Acceptable Quality Limit) sampling plan, such as checking 1 unit every 500.
Q: What is a "Golden Sample"? A: A Golden Sample is a confirmed, working cable kept at the testing station. Before testing the daily batch, the operator plugs in the Golden Sample to verify the tester itself is working correctly.
Q: Can Hipot testing damage the cable? A: No. It is a non-destructive test if the cable is good. If the cable has a defect, the high voltage will burn through the weak spot, revealing the failure—which is exactly what we want to happen in the factory, not in the field.
About the Author
Michael Wang
Senior Technical Engineer
As the technical lead at TeleWire, Michael bridges the critical gap between complex engineering requirements and precision manufacturing. With deep expertise in Design for Manufacturing (DFM) and signal integrity, he oversees the technical validation of custom interconnect solutions for mission-critical automotive, industrial, and medical applications.
