If you're sourcing Nexans cable—or any high-voltage or telecom cable from a major supplier—you already know the spec sheet is just the start. The real test is whether the delivered product matches what you approved.
I review incoming cable deliveries for large infrastructure projects. Over the last four years, I've flagged roughly 12% of first shipments for spec non-compliance. Not all were bad cable—some were just wrong jacket color or termination kits that didn't match. But each one cost time and money.
Here's the checklist I use. It's not theoretical. It's what I run every time a reel of cable arrives.
Step 1: Verify the Physical ID Before You Unspool Anything
The biggest mistake? Assuming the label on the reel matches the cable inside. I've seen two reels from the same batch, same part number, different factories—one was right, one was a lower-voltage variant.
Check three things immediately:
- Reel label vs. your purchase order. Part number, voltage rating, length. If one digit differs, stop.
- Jacket marking. Most manufacturers print the spec on the jacket every 1–2 meters. Confirm it matches the PO spec for voltage class and insulation type.
- Copper strand count. Take a sample cut from the end. Count strands. I once rejected a shipment because it had 37 strands instead of 61 for a high-flex application—the spec called for finer stranding.
If I remember correctly, we had an incident in Q1 2024 where a supplier labeled a 12 kV cable as 15 kV. The jacket marking was correct for 12 kV. We caught it at the reel label level—saved us from pulling 500 meters before discovering it.
Step 2: Cross-Check Insulation Thickness with a Micrometer
Most specs list a nominal insulation thickness with a tolerance. Trusting the supplier's report is fine for low-risk runs. For anything high-voltage or mission-critical, measure it yourself.
Take a cross-section at three points along the cable—both ends and center. Average the measurements. If any single measurement falls below the minimum spec (not the nominal), that's a rejection trigger in my book.
I still kick myself for not doing this on a 50,000-unit order in 2022. The supplier's QA sheet showed nominal thickness. Our field test revealed it was consistently 0.2 mm thin on one production run. That meant 8,000 units of usable but not-spec cable that we couldn't sell at full price. The rework cost us around $22,000.
Step 3: Do the Bend Test (Seriously)
This sounds like something from a workshop manual, but it catches problems that data sheets miss.
Take a 10x cable diameter length and bend it around a mandrel of the specified minimum bend radius. Inspect the jacket for cracks or whitening (stress marks). Then strip a section and inspect the conductor for breakage or deformation.
Why this step? Because cold or poorly compounded PVC jackets become brittle. I've seen 'spec-compliant' cables that passed all paper tests but cracked during installation because of low-temperature brittleness. The datasheet said '-20°C', but the actual material behaved like it was rated for -5°C.
Dodged a bullet last winter when I ran a random bend test on a new batch meant for a rooftop installation in a cold climate. The jacket cracked at -10°C. The supplier had switched to a cheaper compound without updating the datasheet. We rejected 6 reels.
Step 4: Spark Test (Not Just the Manufacturer's Word)
For medium-voltage and high-voltage cable, spark testing is standard at the factory. But I recommend a spot-check spark test on arrival if your facility has the capability.
Run a high-voltage test on a 15-meter sample at 2x the rated voltage + 2 kV (common acceptance standard per IEC 60060). If it arcs at all, reject the full batch.
I'm not 100% sure every project team does this, but ours does for anything above 1 kV. We caught a batch of 5 kV cable in mid-2023 that had a micro-pinhole in the insulation. The factory spark test had missed it—or maybe it happened during shipping. Either way, the cable would have failed under load within six months.
Per IEC standards (iec.ch), spark testing at reduced voltage isn't an alternative to factory tests—but as an incoming QC step, it's your safety net.
Step 5: Measure Conductor Resistance at Both Ends
Conductor resistance tells you more than just the conductor quality. It also reveals if there's a break inside the reel that's not visible externally.
Use a micro-ohmmeter. Measure at both ends. The readings should be within 2% of each other. If one end shows significantly higher resistance, you likely have a broken strand or a poor connection somewhere inside the reel.
This step is the one most people skip. I'll be honest: I didn't always do it either. Learned never to assume the entire length is continuous after a job where we pulled 300 meters and found a dead section in the middle. The factory had spliced a repair inside the reel without marking it. Total waste: 8 hours of crew time.
What to Do When You Find a Problem
This checklist catches problems. The next question is how you respond.
- Document everything. Photos, measurement readings, reel ID, batch number.
- Send a formal non-conformance report. Most major suppliers—Nexans included—will issue a return authorization if you're within the warranty period.
- Don't accept a partial discount. If the cable doesn't meet spec, the cable doesn't meet spec. A discount on substandard cable doesn't fix the risk.
Per FTC guidelines (ftc.gov), claims about product specifications should be substantiated. Your supplier's spec sheet is a claim. Your measurement is the evidence.
Final Note: This is a Spot-Check, Not a Substitute
This checklist is a pragmatic quality gate, not a replacement for full type testing. If you're building critical infrastructure, pay for a full test lab analysis on the first production batch. Use this checklist for ongoing deliveries to catch drift.
Prices and specs as of January 2025; always verify current specifications with your supplier. Regulatory references are for general guidance—consult official sources for current standards.
