Request for quote
What to send with a cable assembly or wire harness RFQ
Quotes are only comparable if every supplier is pricing the same part. This checklist closes the gaps suppliers otherwise fill with assumptions.
The package
Definition of the part
- Drawing, with revision letter. Wiring diagram or schematic, lengths and tolerances, breakout positions, and connector orientation (clocking).
- Bill of materials with manufacturer part numbers for wire, terminals, contacts, connectors, backshells, sleeving and labels.
- Approved alternates. State which substitutions are allowed, or say "no substitutions". An open question here causes most quote differences.
- Customer-furnished material, if you are supplying any parts yourself.
Workmanship and test
- Workmanship standard and class, for example IPC/WHMA-A-620 Class 3. See choosing a class.
- Electrical test: continuity (normally on 100% of parts), plus insulation resistance and dielectric withstanding voltage if required, each with its test voltage, dwell time and limit.
- Other tests: pull tests, cross-sections, environmental or sealing tests, and who performs them.
- First article requirement: AS9102 FAI for aerospace, PPAP level for automotive, or your own format.
Identification and delivery
- Marking and labels: part number, revision, serial or lot, date code, and the label method and location.
- Packaging: coiling, bagging, ESD protection if needed, and labeling of the pack.
- Documentation per shipment: certificate of conformance, test records, material certs.
Commercial and compliance
- Quantities: prototype quantity, first order, and estimated annual usage. Price breaks depend on all three.
- Target delivery date, and whether partial shipments are acceptable.
- Quality and contract flowdowns: your purchase-order terms, AS9100 or IATF requirements, DFARS clauses, and counterfeit-part controls.
- Export classification: whether the drawing is ITAR or EAR controlled. Mark controlled data before you send it, and send it only to suppliers able to receive it.
- Tooling and NRE: ask suppliers to quote formboards, test fixtures and special tooling separately from the piece price.
Package by part type
| If you are buying | Make sure the package also covers |
|---|---|
| A point-to-point cable assembly | Cable specification (jacket, shielding, temperature), overall length and tolerance, strain relief or overmold, sealing rating |
| A branched wire harness | Layout drawing with breakouts, branch lengths, bundling and protection by zone, connector clocking, label positions |
| An overmolded assembly | Mold geometry, compound, color, markings, and who owns the mold. See overmolded cable assemblies. |
| Aerospace or defense parts | AS9102 FAI, quality clauses, counterfeit-part controls, export marking, source inspection |
| Automotive parts | PPAP level, crimp and connector performance specifications, customer-specific requirements |
The drawing itself carries most of this. See what to put on a wire harness drawing for the notes most often missed.
Ask for these back in the quote
Ask every supplier to state the following in their quote, so that you compare like with like:
- Piece price at each quantity break, with tooling and NRE listed separately.
- Lead time for the first article and for production, and the longest-lead component that drives it.
- Any exceptions or assumptions they made about your package, and any parts they propose to substitute.
- How long the quote is valid, especially where connector or metal prices are volatile.
Why the exceptions list matters most. The cheapest quote often carries an exception that removes a test or swaps a connector. Reading the exceptions first can save you from comparing an apple with a cheaper, different apple.
Not sure yet whether you are buying a cable assembly or a harness? Read the difference. It changes how suppliers quote the part.
Common RFQ mistakes
- Sending different revisions to different suppliers. Freeze the package, and send an amendment to everyone if it changes.
- Answering one supplier's question privately. If the answer changes the part or the price, share it with every supplier quoting.
- Leaving the quantity open. "Prototype, then production" produces quotes that cannot be compared. Give numbers, even estimates.
- Hiding the quality clauses. A supplier who learns about AS9102, source inspection or serialized test records after the order has to re-price, or absorb the cost and cut corners.
- Too little time. A complex harness with a long bill of materials needs time to price properly. A rushed quote carries more assumptions and more contingency.
After the quotes come back
- Read the exceptions first and resolve each one, in writing, with the supplier.
- Normalize the quotes: same quantities, tooling separated, same documentation.
- Check the lead-time driver each supplier named, and whether they agree.
- Compare total cost, including tooling amortized over your expected volume, freight and the cost of your own inspection effort.
- Verify the finalists against their certification records before awarding. See how to verify supplier certifications.
Common questions
How many suppliers should get the RFQ?
Enough to compare, few enough to review properly. Many buyers send to three to five qualified or pre-screened suppliers. Send each one the same package, and the same answers to questions.
Should I send an RFQ before the drawing is final?
A budgetary quote on a draft is useful for planning. Mark it as preliminary, and re-quote on the released revision before ordering.
Can I send export-controlled drawings with an RFQ?
Only to suppliers able to receive them under the applicable regulations. Check with your export compliance team before sending, and mark the data correctly.
What is a reasonable quote validity?
It depends on how volatile your components and metal prices are. Ask each supplier to state it, and to say which items are most exposed to price changes, so you know what to re-check before ordering.
Why do quotes for the same part differ so much?
Usually because of different assumptions about class, tests, documentation, component sources and tooling. See what drives the cost of a custom wire harness.
Last reviewed 2026-09-17