Cable Knowledge
Common Cable Questions from International Buyers
International cable buyers usually ask about four things: which conductor size, material and insulation to choose, which standards and tests apply, what a quotation and document package should contain, and how the drums will be packed and shipped. This article gives a short, direct answer to each common question and points to the detailed guide behind it. Use it as a checklist before you send an inquiry.
Which technical questions come up most often?
Most technical questions concern conductor size, conductor material, insulation and sheath, armour, fire behaviour and the governing standard. The table summarises a short answer for each one. Each answer is expanded in its own guide, starting with the logic for choosing a cable size.
| Question | Short answer | Detailed guide |
|---|---|---|
| How do I size a cable? | Check current-carrying capacity after correction factors, voltage drop and short-circuit withstand, then choose the next standard size up. | What Cable Size Do I Need for My Load Current? |
| Copper or aluminium? | Copper gives a smaller conductor for the same current. Aluminium is much lighter and can suit large runs where weight matters, provided the terminations are rated for it. | Copper Cable or Aluminum Cable: Which Should I Buy? |
| XLPE or PVC insulation? | XLPE allows a higher normal conductor temperature, 90 °C against 70 °C for PVC, so it suits hotter or more heavily loaded installations. | XLPE Cable vs PVC Cable |
| Is armour needed? | Choose armour where mechanical damage or direct burial is possible. Multicore cables usually use steel wire armour. | When Should I Choose Armoured Cable? |
| Is LSZH required? | Specify it when the project requires low smoke and low halogen emission in a fire. | What Is LSZH Cable and When Is It Needed? |
| Which standard applies? | IEC standards are common in most export markets. UL and NEC rules apply where the project follows US practice. | IEC Cable vs UL and NEC Requirements |
| What tests should I request? | Routine tests on every cable length, plus type or sample test reports where the standard calls for them. | Cable Factory Testing and Pre-Shipment Inspection |
Table entries are short summaries. Check the standard edition and the manufacturer datasheet for the exact requirement on your project.
Can the cable be customized?
Conductor size, core count, colours, sheath, marking, drum length and some performance options can often be customized. Whether a change is feasible depends on the product standard, raw-material availability, the certification scope and the production quantity.
Ask for every change in writing, with the standard, voltage and construction named, so the supplier can confirm feasibility before quoting. Written technical approval should be completed before custom cable is produced, because a change to the design can fall outside the scope of an existing test report.
What affects MOQ and lead time?
Minimum order quantity (MOQ) varies by conductor size and construction, because extrusion, cabling and armouring lines need setup material for each run. Lead time begins after technical approval and commercial confirmation, not necessarily on the date of the first inquiry. A lead time quoted before the technical scope is fixed may change later.
When you compare quotes, ask each supplier to state the MOQ, the lead time, the date from which the lead time is counted, and whether the figures include testing and document preparation.
Which documents should you ask for?
Typical documents include technical data sheets, routine test records, packing lists and certificates relevant to the ordered product. Keep the document types apart. A factory management-system certificate shows that the factory runs a quality system, but it is not a product approval for the cable you are buying.
Ask for a sample document package before you order, so you can check its format and content. The differences between standards, test reports and certificates are explained in the guide to standards and test reports.
How is export packing confirmed?
Agree the following in writing before production: reel material, flange diameter, net and gross weight, length on each drum, end sealing, shipping marks and container limits. Heavy drums need suitable lifting and unloading equipment at the destination, so confirm this with the receiving party before shipment.
A rough weight estimate helps when you plan lifting. Copper conductor weighs about 8.89 kg per km for each mm² of cross-section (copper density 8.89 g/cm³). Aluminium conductor weighs about 2.70 kg per km for each mm² (aluminium density 2.70 g/cm³). Insulation, sheath and armour add to the total, so use the supplier's stated drum weight for planning.
Agree these drum handling rules with the supplier and the receiving party:
- Handle and store drums upright, never on a flange.
- Lift with a mandrel or shaft through the centre hole and a spreader, or with forklift forks under both flanges, not on the lagging.
- Never drop a drum. Roll it only short distances on smooth ground, in the direction marked on the drum.
- Chock drums with wedges and keep them off ground that can flood.
- Keep all cable ends sealed at all times.
How can you tell if a supplier is ready?
Specific process questions give more useful evidence than asking only whether quality is good. Ask who approves the technical data sheet, how drum traceability links to routine tests, and what happens if conductor resistance or delivered length is disputed.
- Request a sample document package.
- Ask for a written deviation list.
- Confirm who handles technical claims after delivery.
For conductor resistance, compare the measured value with the limit in IEC 60228 for the conductor class. As an example, the maximum DC resistance at 20 °C for a plain copper 16 mm² class 1 or 2 conductor is 1.15 Ω/km. Tinned or other metal-coated conductors have slightly higher limits, so check which conductor type the datasheet describes.
What to confirm before ordering
- Approved technical data sheet, with the standard edition named.
- MOQ, production lead time and the date from which the lead time is counted.
- Product certification scope and the test reports that cover this design.
- Inspection and test plan, including any hold points.
- Marking and packaging drawing, including drum length and labels.
- Written deviation list and any agreed changes from the standard product.
- Warranty, claims and document procedure, including who handles claims after delivery.
Frequently asked questions
Is a factory certificate the same as a product approval?
No. A factory management-system certificate shows that the factory runs a quality system, while a product approval or test report relates to a specific cable design and standard.
When does the lead time start?
Lead time normally starts after technical approval and commercial confirmation, not on the date of the first inquiry. Ask each supplier to state the start point in writing.
What is the routine voltage test for 0.6/1 kV cables?
A commonly listed routine test is 3.5 kV AC for 5 minutes under IEC 60502-1, as shown in many manufacturer datasheets. Confirm the value in the datasheet for your own cable.
Which standard covers cables above 30 kV?
IEC 60840 covers cables above 30 kV up to 150 kV (Um 170 kV). IEC 60502-2 covers cables from 6 kV to 30 kV.
Does a single-core AC cable need steel armour?
Usually not. Single-core AC cables use aluminium wire armour (AWA), because steel armour around a single conductor causes magnetic losses and heating.
Where do I find the minimum bending radius?
Take it from the manufacturer's datasheet. It depends on the construction, the armour and the standard edition, so no single figure applies to all cables.
References
- IEC 60228 (Wikipedia)Conductor classes 1, 2, 5 and 6, and the maximum DC resistance values used in the resistance answer.
- The adiabatic equation (My Cable Engineering)The short-circuit withstand formula referred to in the sizing answer.
- A guide to armoured cable (Prysmian)Steel wire armour for multicore cables and aluminium wire armour for single-core AC cables.
- XLPE vs PVC insulation (Ngoclan Cable)Normal and short-circuit conductor temperature limits for PVC and XLPE insulation.
- Test of LSZH cables (Caledonian Cables)Halogen acid gas and low-smoke test methods for LSZH cables.
Related cable products
- XLPE Insulated Power Cable
- PVC Insulated Power Cable
- Control Cable
- Rubber Flexible Cable
- Welding Cable
- Solar PV Cable
Continue reading
- What Cable Size Do I Need for My Load Current?
- Copper Cable or Aluminum Cable: Which Should I Buy?
- When Should I Choose Armoured Cable?
- Shielded Cable or Unshielded Cable: How to Decide?
Send the cable model, voltage, conductor size, quantity, installation conditions and destination by WhatsApp or email.
Discuss on WhatsApp