Custom Waterproof Cable Harness RFQ: What to Specify

Scope and boundaries

Applies to RFQs for custom waterproof cable harnesses built on circular waterproof connectors (M8–M29, LT20, LP series and similar) for equipment power and signal interfaces. It covers document preparation only: pricing, MOQ, lead time, stock and certification coverage are not stated here and must be confirmed per model with the manufacturer.

Start from why quotes cannot be compared yet

When three quotes for the same harness come back far apart, check configuration before margin: each supplier may have priced a different contact set, termination method, cable or responsibility scope. A series name alone does not fix any of these. Two RFQs that both say M12 can describe different pin counts, codings, genders, cable outer diameters and sealing ranges, so the prices describe different products. Before asking for a price, freeze the configuration in writing; before comparing prices, confirm each quote covers the same configuration and the same scope of work.

Sources: LLT selection guide · Technical applicability

Define the device interface and mating side

Start with what the harness plugs into. Give the mating connector model or the interface drawing, the pin count and the wiring definition per position. Contact gender and housing gender are separate choices, and the end-face view direction plus keying must be shown on the drawing, not inferred from a mirrored image. State the mounting form as well: front or rear panel mount, flange, or in-line cable-to-cable. Panel dimensions such as cutout and board thickness belong to the panel-mounted side; an in-line joint does not have them. Series names like M8 or M12 do not by themselves confirm that two parts mate; matching needs both drawings and confirmed pairing models.

Sources: Technical applicability · LLT selection guide

State loads per contact group, not one combined number

List working voltage, current and core count, and mark each core as power or signal. For mixed configurations such as 3+2, each contact group has its own current and voltage rating; adding the two current ratings into one machine rating is not valid. Conductor cross-sectional area alone does not decide how much current the assembly can carry: simultaneous loading of multiple cores, ambient temperature and heat dissipation all change temperature rise. Catalog ratings are a first screen; the final check is the model's datasheet plus temperature-rise verification under your actual duty.

Sources: Technical applicability · LLT selection guide

Specify the cable as three separate values

Conductor size, wire gauge and jacket diameter are three different specifications. Give conductor cross-sectional area per core in mm²; give AWG as the gauge number, using the catalog's correspondence rather than converting on your own. Give cable outer diameter over the jacket in mm, because the rear clamp and seal are matched to a defined OD range: a cable whose conductors fit can still fail to seal if its jacket OD falls outside that range. Two cables with identical conductor area can have different ODs because of core count, insulation or jacket. Then add length with tolerance, flexing or fixed routing, wire-out direction and end termination. Each missing value becomes an assumption, and assumptions differ between quotes.

Sources: Technical applicability · LLT selection guide

Map every branch, breakout and tail treatment

A branched harness needs its geometry defined in writing, not implied. For each branch, state where it leaves the trunk (distance from a defined reference), which cores it carries, its wire-out direction and its own length with tolerance. Describe every tail: stripped and tinned, terminated to another connector, or left for field assembly, and note any labeling or sleeve requirements. If routing space on the machine is tight, mark which branch exits are adjustable and which are fixed. Without a branch drawing and a wiring table, each supplier quotes a different breakout geometry and the prices cannot be reconciled.

Sources: LLT selection guide

Write down environment and verification conditions

Environment decides materials, sealing and verification. IP67 means dust protection and short-term immersion under defined test conditions: correctly mated and locked, seals intact, cable OD within the sealing range, installation sealed. Unmated ports, the cable's far end and the panel opening need separate measures. Long-term immersion and high-pressure washdown are different conditions; provide water depth, duration, temperature, medium and cleaning method if they apply, and ask for configurations with corresponding validation before pricing. Stated figures such as UV resistance over 1,000 hours or salt spray over 480 hours are supplier-declared performance for specific material and plating combinations; they do not convert into years of service, so confirm the applicable configuration and request the records. UL 94 V-0 is a plastic material rating, not product certification; for UL 2238, UL 1977, TÜV, SAA or CE, ask for documents covering your exact model and ratings.

Sources: Technical applicability · LLT selection guide · IEC 60529 — Degrees of protection provided by enclosures

Attach drawings, samples and acceptance documents

An interface drawing, the mating model number or an existing sample each works as an evaluation starting point; the wiring definition and pin assignments still need to be stated explicitly. Define acceptance before award: which dimensions are checked, what electrical checks apply to each circuit, and which test reports or certificates must ship with the order. Where a claimed performance value matters to the project — plating thickness, UV duration, salt spray hours, vibration and temperature-rise results — request the corresponding specification or test record for that configuration. Rendered product images show material intent, not measured results, and should not be used as acceptance evidence.

Sources: Technical applicability · LLT selection guide

Quantities, delivery scope and the submission checklist

State quantities per delivery and expected total volume, and fix the scope: harness only or with the mating part, who supplies the cable, and whether the model supports your overmolded or field-assembly termination. Price, MOQ, lead time and stock are not stated in this article; confirm them in writing for the agreed configuration. A quote received before these items are fixed is a budget indication, not a comparable offer.

Send this checklist with the interface drawing and any sample; mark open items as to be confirmed so the reply states its assumptions.

• Interface: mating model or drawing, pin count, wiring definition, genders, mounting form
• Loads: voltage and current per contact group; power and signal marked separately
• Cable: mm² per core, AWG where used, jacket OD in mm, length with tolerance
• Branches: position, cores carried, wire-out direction, tail treatment
• Environment and acceptance: conditions, validation items, certificates for the exact model

Sources: LLT selection guide · Technical applicability

Frequently asked questions