A sealed splice quotation needs more than a conductor size and the word “waterproof.” Identify the exact splice, every wire entering it, the arrangement on each side and the moisture path the assembly must resist. Otherwise, two suppliers can quote different connections against the same drawing note.
This guide focuses on permanent wire junctions within a harness. Start with the harness pinout and wire identification guide to establish which wires belong together. Electrical connectivity, wire accommodation and environmental sealing each need their own acceptance evidence.
Define the junction before selecting the splice
Give each splice a drawing identifier and list its connected wire IDs. Describe whether wires enter from opposite ends in an in-line butt connection or form a stub connection. A branch is an electrical function; its name alone does not specify the physical termination arrangement.
Show the wire count at each entry, the direction of each branch and the boundaries of any protective covering. Keep the internal electrical junction distinct from the visible bundle breakout. The harness length and breakout guide explains how to define those locations without relying on an ambiguous tape edge.
Ask the bidder to identify the manufacturer, complete part number and applicable drawing revision. If the proposal combines a separate barrel, sleeve and sealing inserts, require all constituent identities. A color, generic size range or photograph cannot establish that the supplied combination matches the documentation.
Keep conductor area and wire arrangement separate
Prepare a wire schedule recording quantity, conductor specification, strand construction, plating where applicable, nominal conductor area, insulation material and insulation outside-diameter range. Preserve the wire manufacturer's dimensional tolerances. Using one measured sample diameter as the entire production range can leave part of the intended supply unassessed.
TE's MiniSeal selection guide distinguishes the arithmetic by construction: add all conductor areas for a stub splice, but calculate the two sides of a butt splice separately. Its selection process then checks barrel capacity and the sealing sleeve. This is guidance for the documented MiniSeal range, rather than authorization to put multiple wires into any butt connector. The catalogue footer is marked “Revised 5-12”; confirm current part documentation before selection. TE MiniSeal D-436 catalogue, page 8-24.
For your RFQ, retain both the calculation and the individual wire list. A total conceals how many insulated surfaces must be accommodated. Do not add AWG numbers; use the applicable conductor-area data and one consistent unit. Have the supplier identify the basis of any conversion instead of mixing rounded catalogue values with nominal metric cable sizes.
An area calculation is a selection input. It does not establish allowable circuit current, the suitability of the branch protection or compatibility with the intended conductor construction. Those remain engineering requirements in the harness specification.
Check the manufacturer's permitted wire configuration
TE's DuraSeal customer drawing D-406-00XX, revision C4 dated May 29, 2026, describes an environment-resistant one-to-one in-line splice. It requires compliance with both conductor-size and wire-diameter restrictions. For that drawing, a wire combination with the same total area does not establish permission to substitute a multiwire branch. TE DuraSeal customer drawing, application notes.
The MiniSeal catalogue addresses multiple-wire arrangements separately. It asks users to compare the wires' outside diameters with the sealing-insert openings and limits each opening to two wires for a reliable seal. That is a limit within the cited selection guidance, not a general two-wire allowance for unrelated products. TE MiniSeal selection guidance.
Request a marked drawing showing which wire occupies each permitted entry. Have the supplier reconcile the proposal with the current product drawing and application instructions, especially when an older catalogue and a newer document differ. Do not resolve an undersized wire, excess wire count or unavailable variant through an undocumented production adjustment.
Define what “sealed” must demonstrate
Write the moisture requirement as a defined boundary and exposure. Is the requirement to protect the junction from water entering around the wire insulation? To stop migration between insulated wires along a bundle? Or to interrupt a path through the conductor strands beneath insulation? These are different paths to identify in the design review.
A watertight claim alone does not prove longitudinal water-blocking along every possible path. Ask where water is applied, which ends remain exposed, what boundary must remain dry and how that condition is verified. A supplier's evidence must address the claimed path; a description of the outer sleeve is insufficient to establish what happens inside a conductor.
TE's RayBlock page describes a separate bundle-sealing system: an adhesive profile and tubing form a plug around individual wires by filling spaces within the bundle. The description concerns bundle voids; it does not establish a barrier within stranded conductors. This illustrates why the location of the seal matters. TE RayBlock sealing kits.
For the proposed splice, request evidence identifying the specimen configuration, wire types and diameters, installation specification, conditioning, exposure medium, temperature, duration, pressure or immersion conditions where relevant, and acceptance criteria. These are fields to agree for the application, not universal test settings. State whether the report covers a component specimen or the finished harness arrangement.
Compare two fictional branch-splice quotations
The following is an invented RFQ exercise, not a customer case, tested design or recommended wire sizing. Harness H-043 revision A contains splice S1. Its drawing calls for one 1.5 mm² wire at side A and three 0.5 mm² wires at side B. The intended external water exposure is described, but the buyer has not yet resolved whether a longitudinal migration barrier is needed.
Each side totals 1.5 mm². Adding both sides produces 3.0 mm², but that combined number obscures the required one-to-three arrangement. Neither figure identifies insulation diameter or an approved sealing configuration.
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| Quotation response | Evidence gap | Buyer disposition |
|---|---|---|
| A offers D-406-0002 because each side totals 1.5 mm² | The cited DuraSeal drawing supports one-to-one use; the proposed branch arrangement lacks supporting documentation | Hold this selection and request a documented alternative |
| B names a multiwire splice and lists the three side-B wires individually | Its report covers a different insulation diameter and only says “waterproof” | Request matching configuration evidence and a defined sealing boundary |
Quote B is more informative, but neither response is ready for technical acceptance. Do not rank their prices as equivalent until they address the same wire schedule and environmental requirement. Ask each bidder to separate the assembly price from proposed sample evaluation or documentation work, so an unresolved evidence gap does not disappear into a low headline price.
Release the approved combination into production
Create one controlled record linking splice S1, the harness revision, wire identities, component parts, permitted arrangement and accepted evidence. Record the approved exceptions and their limits. A report for another wire combination should remain visibly separate until engineering accepts its relevance or additional evaluation closes the gap.
Require review when a change affects conductor construction, insulation diameter or material, splice variant, sealing insert, or the process specified for that combination. A substitute wire with the same nominal area can still require a new fit and sealing assessment. The first-article and change-control guide covers the broader approval record.
Send a sealed splice RFQ
Send the junction drawing, each-side wire schedule, proposed moisture boundary, quantities and evidence requirements. Ask for an identified splice proposal with explicit deviations and commercial terms tied to the agreed scope.
Buyer FAQ
Can the same splice serve every combination with equal total area?
No. Verify the permitted wire count, arrangement, conductor construction and insulation diameters for the exact part. Equal area alone does not demonstrate the required fit or sealing geometry.
Does a watertight splice stop water travelling along the cable?
That conclusion needs evidence for the identified longitudinal path. Ask whether the evaluation covers spaces between insulated wires, the conductor interior or another boundary. Do not infer all three from one sealing claim.
Is an older manufacturer catalogue enough to approve a branch?
It can support initial screening. Obtain the current drawing and applicable instructions for the proposed part, resolve discrepancies and match the actual wire combination before approval.
What information makes supplier prices comparable?
Use the same wire schedule, splice configuration, exposure requirement, acceptance evidence and quantity. Request separate identification of samples, additional evaluation and documentation work, together with the supplier's proposed delivery conditions.