Properly made EV charging cables contain copper conductors, but not every cable on the market uses solid copper. Some low-cost cables use copper-clad aluminium (CCA), which looks like copper on the surface. You can check by measuring conductor resistance, comparing weight with the stated core sizes, and asking for the cable test report. Pure copper cores of a given size have a predictable resistance that aluminium-based cores cannot match.
Key Takeaways
- Well-made charging cables use solid copper strands.
- CCA looks like copper but has higher resistance.
- Compare measured resistance with the NIST copper value for the core size.
- Specify copper conductors and a resistance limit in the contract.
Why CCA Matters in a Charging Cable
Aluminium conducts about 60% as well as copper, so a CCA core of the same nominal size has higher resistance. Higher resistance means more heat at the same current, and charging runs at high current for hours. CCA strands are also less tolerant of repeated bending and can be harder to crimp reliably into connector pins. That is why material substitution in a cable is a safety question, not just a cost question.
Check 1: Conductor Resistance
Resistance of a copper conductor follows from the International Annealed Copper Standard, documented in NIST’s copper wire tables: 0.017241 ohm for a 1 m length of 1 mm² at 20 °C. Divide by the area and multiply by the length to get the expected value.
| Core size | Copper, 7.5 m at 20 °C | If the core were all aluminium (about 61% IACS) |
|---|---|---|
| 2.5 mm² | about 52 milliohm | about 85 milliohm |
| 6 mm² | about 22 milliohm | about 35 milliohm |
| 8 AWG (8.37 mm²) | about 15 milliohm | about 25 milliohm |
| 6 AWG (13.3 mm²) | about 10 milliohm | about 16 milliohm |
CCA falls between the two columns depending on its copper share. Values this small need a four-wire (Kelvin) milliohm meter, and the reading must be corrected for temperature, because copper resistance rises about 0.39% per °C (NIST’s coefficient 0.00393). A reading well above the copper column is a reason to cut a sample open. Stranding and tinning add a little resistance, so compare against the cable standard’s maximum value as well.
Check 2: Weight, Look and Paperwork
- Weight: copper is about three times denser than aluminium. A cable that is much lighter than a same-spec sample deserves a closer look.
- Cut and scrape test: on a destructive sample, scrape a strand. CCA shows a silver core under a thin copper skin.
- Documents: ask for the cable certificate, the conductor material declaration and the test report that lists conductor resistance.
- Listing: make sure the complete charger, cable included, carries the required certification for your market.
Build these checks into incoming inspection. Our guides to pre-shipment inspection and AQL sampling and testing a sample before a bulk order show where they fit. For cable types and ratings, see whether all EV charging cables are the same.
What Buyers Should Put in the Contract
Write “copper conductors” and the core sizes into the specification, along with the cable standard and a maximum conductor resistance. State that any material change needs written approval. EVDANCE manufactures in its own Shenzhen factory and uses copper conductors in models such as the EV-ACT5006T 48A Level 2 wall charger. Brands can request cable documents through the OEM program.
Frequently Asked Questions
Can I tell CCA from copper by looking at the cable?
Not from the outside. CCA has a copper surface. You need a resistance test, a weight comparison or a cut sample.
Is CCA illegal in EV charging cables?
Rules depend on the cable standard and the certification. Many standards specify copper conductors. Check the standard your product is certified to.
Does a multimeter show the difference?
A normal multimeter cannot resolve a few milliohms. Use a four-wire milliohm meter or a lab test.
Related Reading
- Are All EV Charging Cables the Same?
- Pre-Shipment Inspection and AQL Sampling for EV Charger Orders
- How to Test an EV Charger Sample Before a Bulk Order
- EV Charger Factory Audit Checklist for Importers
