How to Compare Cable Suppliers and Avoid False Economy

Does every bidder receive the same specification?

Price comparisons only mean something when every supplier has quoted the same product. Write one specification that names the standard and edition, conductor class, insulation and sheath compounds, voltage rating, cores, cross-sectional area, armour and test requirements. Send the same document to every bidder.

Ask each supplier for a completed compliance schedule that answers, for every clause, complies, deviates or not offered. A general statement such as "fully compliant" hides what was actually offered.

Answers to clarification questions should be written into the contract documents. A verbal assurance given during the tender can be forgotten by the time of delivery.

What technical data should you compare line by line?

Conductor resistance is the first check. For plain copper conductors of class 1 or class 2 at 20 °C, IEC 60228 sets maximum DC resistance values, for example 7.41 Ω/km for 2.5 mm², 1.15 Ω/km for 16 mm² and 0.193 Ω/km for 95 mm². Tinned or other metal-coated conductors have slightly higher limits, so the coating must be stated in the offer.

Insulation temperature rating is the second check. Commonly cited normal maximum conductor temperatures are 70 °C for PVC and 90 °C for XLPE (IEC 60502-1 and manufacturer data). A different material from the specification must appear in the deviation schedule.

Mass is a useful cross-check. Copper has a density of 8.89 g/cm³, or about 8.89 kg per km for each mm² of conductor. A mass far below this estimate suggests a smaller conductor than the datasheet claims.

Bending radius, grouping factors and medium-voltage test voltages depend on the cable construction and standard edition, so take them from the manufacturer datasheet.

How do you check quality evidence and test reports?

A test report is only useful when it describes the product being ordered. Check that it names the same size, cores, compounds and construction as the offer, and the site that will supply the cable. Reports from a different plant or an earlier design are background only.

Ask whether the supplier's approvals are issued for the offered product, and how production runs are traced to individual drums. Traceability matters when a problem appears after installation.

If halogen-free performance is required, ask for the IEC 60754-1 and IEC 61034-2 reports. Under IEC 60754-1, halogen acid gas content of 0.5 % or less (5 mg/g) is a common LSZH acceptance value. Under IEC 61034-2, light transmittance of at least 60 % is commonly used to classify low smoke, although some sectors require more. See cable standards and test reports for more detail.

What commercial and delivery terms can hide extra cost?

A quote becomes comparable only when its terms are equal. Check the validity period, whether the price is adjusted with the copper or aluminium price, and how that adjustment is calculated. A metal-price clause without a formula or named index can change the final invoice unexpectedly.

Minimum order quantity, drum length and lead time decide whether an order fits the project. A short drum length can mean more joints in a run, and each joint is an extra point to test. Confirm the Incoterm to show who pays freight, insurance and import charges, and when risk passes to the buyer.

A vague low quote may later accumulate extras for testing, packing or documentation, so ask each bidder to list what is included and what is excluded.

Ask how drums are protected, labelled and sealed. Drums should be moved upright, lifted through the centre hole or with forks under both flanges, never dropped, and kept off flood-prone ground. The drum packing and shipping guide covers these points.

How should claims and disputes be handled?

Agree the claim procedure before ordering. The contract should state how shortages, transport damage and test disputes are documented, who inspects the goods, and how disputes are settled.

Keep drum labels, photographs of the packing and any damage, and the delivery documents. Record drum numbers and quantities at receipt. If a test result is disputed, independent test evidence carries far more weight than a verbal explanation.

How should you score bids before comparing prices?

Score each bid on compliance, test evidence, manufacturing control, delivery, documentation and claims support before opening the commercial comparison. A bidder that leaves many assumptions unstated should not score the same as a fully documented offer.

Use a signed deviation schedule so every exception is visible to both parties. Verify the manufacturing site named in the offer, and treat any change of factory as a new deviation. Then compare final prices on the same scope and payment terms.

Frequently asked questions