Waterproof Power Connector Current Assessment per Contact

Scope and boundaries

This article applies to equipment power circuits where the buyer must confirm how much current a specific contact group of a waterproof connector can carry and how temperature rise is verified. It covers LLT's published rating method, one LP-32 vibration condition and the cable checks that bound the assessment. These materials establish how LLT marks rated current and one LP-32 verification condition; they do not provide per-SKU temperature-rise curves or contact-group derating tables, so final confirmation requires the model-specific specification sheet and the corresponding test report.

Start from the load each circuit actually carries

On equipment power circuits, the first limiting condition is the current each circuit carries and how many contacts carry it at the same time, not the housing diameter or the largest figure printed anywhere in a series. For a waterproof power connector, the current assessment starts from the actual load per circuit and the contact group that carries it, because LLT marks rated current per individual contact or designated contact group, and temperature rise depends on simultaneous loading, conductor size, ambient temperature and heat dissipation, so the catalog number is an initial screen, not a final verification.

A flange that fits the panel cutout proves only that the interface fits the panel. It says nothing about whether the contacts, the wired conductor and the installation can sustain the load without excessive heating. Current capability is a property of the contact group, the cable and the duty, and the three have to be checked together before a configuration is cleared.

Sources: Technical applicability

Read the rating as a contact-group value, not a housing value

Rated current is marked per individual contact or per designated contact group of the selected configuration, and rated voltage is marked for the corresponding insulation structure. Two configurations in the same series can therefore carry different ratings, and a series maximum does not automatically apply to every SKU in that series.

Mixed pin counts make this stricter. A marking such as 3+2 describes the number of contacts in two contact groups; the current, voltage and wiring specifications of the two groups must be checked separately, and the rated currents of the two groups cannot be added together as a whole-machine rating. Treat the power group and the signal group as two assessments that happen to share one shell, each with its own wiring and verification requirements.

Sources: Technical applicability

Four conditions that move the temperature rise

The same contact group runs at different temperatures depending on how it is used. LLT's technical notes list the conditions that change temperature rise and allowable current:

If several power contacts will carry load simultaneously at high ambient temperature, first request the model's temperature-rise verification for that loading pattern; until that is confirmed, the per-contact rating alone cannot clear the configuration. The same logic applies when the duty, ambient or enclosure ventilation is not yet defined: gather the operating conditions before comparing candidate models, because a comparison built on undefined conditions cannot be checked later.

• Simultaneous energization of multiple cores, not only the single-contact value
• Conductor cross-section of the wired cable
• Ambient temperature around the installed connector
• Heat dissipation conditions of the installation

Sources: Technical applicability

What the LP-32 120 A vibration figure does and does not say

In the company-provided verification information for LP-32, a 120 A load under 6 g random vibration produced a temperature rise of no more than 25 °C above ambient. Two boundaries matter. The figure is a temperature rise — the increase above ambient temperature — not an absolute contact temperature, so the actual contact temperature still depends on the installation's ambient. And the result applies to the tested sample: the applicable sample version, wire, spectrum, direction, duration and measurement points follow the corresponding test report, and the result cannot be extrapolated to all vibration or installation conditions.

Treat this as evidence that a specific LP-32 configuration held temperature rise within 25 °C under the stated condition, and as a prompt to request the report when your duty resembles it — not as a blanket rating for every LP-32 variant or every vibration profile. This is company-provided performance information, so ask for the corresponding report for the exact configuration you intend to use.

Sources: Technical applicability

Cable size is two checks, not one

Conductor cross-section is specified per core in mm² and screens the current path; the catalog upper limit gives a first filter for conductor carrying capacity. Cable outside diameter is the jacket OD in mm, and it screens the sealing and clamping structure. The two units describe different things and must not be mixed. AWG is a wire-gauge designation for conductor size; where the catalog provides a verified correspondence, AWG and mm² can be cross-referenced, but the jacket OD is still checked separately.

Cables with the same conductor cross-section can differ in outside diameter because of core count, insulation or jacket. The cable OD must fall inside the sealing adaptation interval of the exact configuration — checking only that the product maximum exceeds the cable OD is not enough. A cable whose conductor meets the catalog upper limit can still fail the build if its jacket outside diameter is outside the sealing adaptation interval of the exact configuration. If the OD falls outside the published range, confirm the corresponding configuration with the supplier rather than assuming a seal can be swapped in the field.

Sources: Technical applicability · LLT selection guide · LLT public connector catalog

What to submit before a configuration can be cleared

Selection results are an initial screen; final confirmation is per the actual duty against the specification sheet and temperature-rise verification. To make that check possible, submit the operating conditions together with the interface data:

One more boundary: connectors that are not explicitly rated for live mating should be operated de-energized, and installation and maintenance follow the product specification and the equipment's safety requirements. No per-SKU parameter table is included in this article, so request the model-specific specification sheet and the corresponding test report for the shortlisted configuration.

• Working voltage, current per circuit, core count, and whether each contact group is power or signal
• Interface drawing or mating model, wiring definition, and pin/socket gender
• Conductor cross-section per core and the cable jacket outside diameter with material
• Wire length and tolerance, branch positions, exit direction and tail-end treatment
• Ambient temperature, simultaneous-loading pattern, vibration exposure and the verification items required

Sources: LLT selection guide · Technical applicability

Frequently asked questions