Ask for identifiers, not assurances
“UL listed”, “QPL approved” and “ISO certified” are sentences. A listing file number, a qualification reference and a certificate number are facts that someone other than the seller holds. The first request to any prospective supplier is for the identifier behind each claim on its line card, and for the name of the body that issued it.
| The claim | Ask for | Check it at |
|---|---|---|
| Listed by a test laboratory | The file number and the product category | The laboratory’s public directory: UL, CSA or Intertek |
| On a qualified products list | The specification, slash sheet, plant and qualification reference | The US government’s qualified products database |
| Quality system certified | The certificate number, scope and certification body | IAF CertSearch for ISO 9001; the OASIS database for AS9100 |
| Meets a standard | The test report, naming the standard and its edition | The report itself, and the laboratory that signed it |
Two details are easy to miss. A listing covers named product types, so confirm the type on your drawing is in it. And a quality-system certificate has a scope and a site address: a certificate for a sales office says nothing about the plant. Step-by-step lookups for the quality-system registers are in a companion guide at bestcablemfg.com.
What should arrive with the wire
Qualification does not end at the purchase order. The paper that comes with each shipment is how you know the reel in front of you is the product that was qualified.
- A certificate of conformance naming the specification and revision, the part number, the quantity, and a lot or reel number that is also printed on the reel tag.
- A certified test report for that lot when the specification requires one: conductor resistance, diameters, insulation and jacket thickness, and the electrical tests.
- The print legend. Most insulated wire is marked along its length. What is printed on the wire should agree with the certificate and the tag. It is the one record that cannot be separated from the product.
Ask a new supplier for a sample set of these documents before ordering. A mill produces them every day and will send them without difficulty. Hesitation is information.
Process questions worth asking
- Is the insulation spark-tested along its full length? In-line spark testing finds pinholes as the wire is made. Ask what happens to a length where a fault is found: cut out, repaired, or marked.
- What is the policy on splices? Conductor joints and insulation repairs are allowed in some products and forbidden in others. Know which you are buying, and the shortest continuous length the mill will ship.
- Where does the conductor come from? Some mills draw their own rod; others buy drawn or stranded conductor. Neither is wrong, and the answer tells you how far traceability goes.
- How is a lot defined? One extrusion run, one shift, one batch of compound? The definition sets how much wire is in question if a problem is found later.
- What are the minimums and the put-ups? A mill may not run less than several thousand feet of a construction. If you need less, the realistic source is a distributor that stocks that mill’s product. See Manufacturer, distributor or processor.
Commercial terms that hide in wire quotes
Copper is most of the cost of most wire, and its price moves daily. Quotes deal with this in different ways: a fixed price valid for a few days, a price tied to a published copper index on the day of shipment, or a base price with a metal adder. Two quotes can differ by more than the mills’ margins purely because of when and how copper was priced. Ask each supplier to state the copper basis, and compare on the same one.
Length tolerance is the other quiet term. Wire is commonly sold with an allowance on shipped quantity, and reels may arrive as several lengths adding up to the order. If the job needs one continuous length, say so on the purchase order.
Compliance paper beyond the product
Depending on the program, a buyer may also need declarations on restricted substances, on the origin of metals, and on the country where the wire was made. These are statements by the supplier, not test results. Request them by name, for the specific part, and keep them with the lot records. Where a contract has domestic-content terms, the declaration needs to describe the reel that shipped.
A short order of work
- Fix the specification and revision on the drawing. Reading a wire specification covers what it must state.
- Find candidate makers for that family in the register, and beyond it.
- Request identifiers and sample shipment documents. Verify each at its source.
- Ask the process and commercial questions above, in writing.
- Buy a first lot, read the wire, and reconcile legend, tag, certificate and test report before using it.