A cable price is not one number. It is a base price plus a copper surcharge, and the two behave completely differently: one is stable for months, the other moves every working day. Estimators who quote from a catalogue PDF and get surprised by the invoice are almost always looking at only the first half.
Why cable is priced in two parts at all
Copper is a traded commodity; the plastics, the labour and the drum are not. If a cable maker published a single all-in price, they would have to re-publish the entire catalogue every time the metal moved, and they would carry the price risk between publication and delivery. So the trade split the price where the risk sits:
- the base price covers everything that is not the copper — insulation, jacket, shielding, stranding, drum, margin. It changes when the supplier revises the price list, typically a few times a year;
- the copper surcharge covers the metal, and is recalculated from the exchange quotation on the day the order is placed.
This is why a cable quoted at €0.42/m in a catalogue can be invoiced well above that. The catalogue price was never the whole price.
The three numbers you need
The copper number
The copper number (in German, Kupferzahl or Cu-Zahl) is the mass of copper in the cable, in kilograms per kilometre. It comes from the cable’s construction — cross-section, number of cores, whether there is a copper braid — and it is a constant for that article. The supplier publishes it next to the base price. It is the reason a 4 × 25 mm² cable is exposed to metal prices roughly twenty times as much as a 4 × 1.5 mm² one.
The reference quotation
In the German-speaking market the reference is the DEL notation(Deutsches Elektrolytkupfer für Leitzwecke), published each working day in euros per 100 kg. Most suppliers do not settle on the bare notation but on the notation plus a procurement markup — “DEL plus 1 %” is the common convention. Outside that market the same role is played by an LME-based quotation, but the arithmetic is identical.
The copper base
The copper base is the copper price that is already inside the base price. If the base is €150 per 100 kg, the supplier has pre-paid for copper at that level and the surcharge only bills the difference. Bases of 100 and 150 are both widespread, and some price lists use a base of zero, meaning the base price contains no copper at all and the surcharge carries the entire metal cost.
This is the field people get wrong. Comparing two suppliers’ base prices without checking their copper bases compares nothing at all — a base price at Cu 150 and one at Cu 0 are different quantities wearing the same label.
The calculation
Put together, per kilometre of cable:
surcharge [€/km] = copper number [kg/km] × (quotation × 1.01 − copper base) [€/100 kg] ÷ 100
A worked example, using a copper number of 100 kg/km, a DEL notation of €850/100 kg and a copper base of 150:
| Step | Value |
|---|---|
| Settlement quotation (DEL + 1 %) | €858.50 / 100 kg |
| Less the copper base | − €150.00 / 100 kg |
| Billable copper | €708.50 / 100 kg |
| × copper number 100 kg/km ÷ 100 | €708.50 / km — that is €0.71 per metre, on top of the base price |
Whether the base price was €0.42/m or €0.95/m, the surcharge here is the larger share. Any quote built on the catalogue number alone is not slightly off. It is wrong by more than the price it used.
What this means for a harness quote
Exposure is not spread evenly across the BOM
Connectors, contacts, seals and sleeves carry no copper number worth speaking of. The metal risk in a harness sits almost entirely in a few heavy-gauge power lines and in total cable length. Two harnesses with the same number of BOM lines can have completely different sensitivity to the copper price, so a flat percentage buffer across the whole quote either overprices the connector-heavy job or underprices the power harness.
Lot size enters through a different door
Cable is sold from the ring or cut to length, and a cut usually carries a fixed cutting charge per order. That charge is a per-order cost, not a per-metre price. Dividing it into a €/m figure makes short cuts look absurdly expensive and quietly corrupts every comparison against a full ring. Keep the cutting charge as its own line; it belongs to the order, not to the metre.
Your quote has a shelf life whether you state one or not
The surcharge is recalculated on the order date, not the quote date. If you quote today and the customer orders in six weeks, the difference is yours unless you said otherwise. Three defensible options: keep the validity period short, name the notation and date the quote was based on, or include a price-adjustment clause tied to the published quotation. What does not work is quoting a fixed price for ninety days and hoping.
How Nuqo handles it
Nuqo prices cable lines from live distributor data rather than from a stored catalogue figure, so the copper component reflects what the material actually costs at the time of calculation, and the cost breakdown shows the per-line basis it used. That removes the stale-catalogue error. It does not remove the commercial decision: how long you hold the price, and whether you carry the metal risk or pass it through, is still a call for the person signing the quote.
