Waterproof Connector Selection: Start With Load and Cable

Scope and boundaries

Applies to initial screening of circular waterproof connectors for industrial power and signal interfaces, covering series from M8 up to high-current configurations such as LP-32. These materials define selection conditions and evidence levels; they do not include model-specific datasheets, torque values or strip lengths, so final confirmation still requires the drawing and specification for the exact part number.

Fix the electrical duty before any series name

The condition that limits selection first is usually the electrical duty, not the shell size. Define working voltage, current, the number of power and signal ways, and which circuits load simultaneously. Rated current is stated per contact or per specified contact group of the chosen configuration, and rated voltage applies to the corresponding insulation structure. If the electrical duty, the cable jacket OD and the mated locking state are not confirmed for the exact configuration, an IP67 mark alone cannot qualify the part.

A '3+2' marking describes two contact groups whose ratings must be checked separately; they cannot be added into one machine rating. Multi-core simultaneous loading, conductor cross-section, ambient temperature and heat dissipation all shift allowable temperature rise, so treat catalog ratings as a first screen and confirm against the specification under real duty.

Sources: Technical applicability · LLT selection guide

Treat IP67 as a mated-state result

IP67 means dust-tight construction and short-term immersion protection under specified test conditions. It holds when the connector is correctly mated and locked, seals are intact, the prescribed cable OD is used and installation sealing is completed; unmated ports, the far end of the cable and the device opening need their own measures.

Continuous underwater running and high-pressure washdown are different test conditions and need separate verification: give the engineering team water depth, duration, temperature, medium and cleaning method, then pick a configuration holding corresponding data. The IP6X dust requirement applies to a confirmed sealed state — keep end faces, seals and locking features clean — and it never qualifies a connector for explosive dust atmospheres.

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

Choose locking, mounting and contact form separately

Front panel, rear panel, flange and in-line cable-to-cable describe mounting structures; pin and socket describe contact forms, and the two choices are independent. Board thickness, panel cutout and locking conditions follow the part-number drawing, and a face view must state its viewing direction and keying datum — a mirrored view never proves intermateability.

Series labels prove nothing either. For two parts both marked M12, confirm interface dimensions, thread or locking structure, coding, pin count, pin positions and the mating model; where the interface carries industrial communication, add shielding and link requirements, and judge from both drawings plus verification rather than the name.

Sources: Technical applicability · LLT selection guide

Match the cable twice: conductor in mm², jacket OD in mm

Conductor cross-section is specified per core in mm², while AWG is a gauge numbering system; cross-check AWG only against the correspondence stated in the catalog for the specific terminal. The jacket OD in mm is an independent sealing condition and must sit inside the sealing adaptation range of the configuration — it is not enough that the product maximum exceeds your cable. Cables with identical conductors can differ in OD through core count, insulation and jacket design, and the jacket material must also suit fixed or moving routing, bending, temperature and media.

If the measured cable jacket OD is outside the sealing adaptation range, stop and re-check the configuration or the cable with the supplier; do not assume a different seal can be fitted, because these materials do not state that seals are user-replaceable. LLT can evaluate cable and connector together before you commit to a harness build.

Sources: Technical applicability · LLT selection guide

Read environment and material claims per configuration

UV resistance of 1,000 hours or more and salt spray of 480 hours or more are company-provided figures tied to material grade, color, product version, plating thickness and the corresponding test record; accelerated hours cannot be converted into outdoor service years, and appearance and electrical criteria are judged separately.

UL 94 V-0 is a flammability rating for a plastic material such as the listed PA66-RG301 grade, and a UL Yellow Card covers that material, not the finished connector; the company-provided 2 μin gold plating figure (about 0.0508 μm) applies only to configurations marked with it. UL 2238, UL 1977, TÜV, SAA and CE coverage follows the models, ratings, structural versions and validity stated on each certificate, so request the documents for your target SKU and sales market.

Sources: Technical applicability · LLT selection guide

What configuration-level evidence looks like

For the LP-32, the company provides verification information of 120 A load under 6 g random vibration with temperature rise not exceeding 25 °C, where the rise is measured above ambient rather than as an absolute contact temperature. The applicable sample version, wire, spectrum, direction, duration and measuring points follow the test report, and the result cannot be extrapolated to all vibration or mounting conditions. Treat this as the evidence level to request for your own duty.

No model parameter table accompanies this guide, so for each candidate request the rated values of the exact configuration, contact group definitions, conductor range per terminal, sealing OD range, panel cutout and board thickness, the mating part number, and temperature-rise or vibration verification; the catalog locates the series, and part-number documents close the decision.

Sources: Technical applicability · LLT public connector catalog

Send a complete requirement set before pricing

A complete requirement set shortens both quotation and sampling:

Plan installation and maintenance de-energized unless the exact configuration is rated for live mating, keep sealing faces clean and confirm seal seating before locking. These materials define selection conditions and evidence levels; they do not include model-specific datasheets, torque values or strip lengths, so final confirmation still requires the drawing and specification for the exact part number.

• Interface drawing or mating model, with pin count and wiring definition
• Working voltage and current per circuit, including simultaneous loading
• Cable length with tolerance, jacket OD and jacket material
• Branch positions, exit direction and end treatment for harnesses
• Environment: rain, immersion, washdown, UV, salt fog and temperature range
• Verification items, target model, application and sales market for certificates

Sources: LLT selection guide · Technical applicability

Frequently asked questions