Waterproof Wiring for Horticultural Lighting: Trunk and Dimming

Scope and boundaries

Applies to grow-house and greenhouse LED lighting wired with LLT wire-to-wire waterproof connectors at four points: driver power input, driver-to-strip output, dimming and control, and trunk-to-branch distribution. Horticultural lighting trunk and dimming wiring stays waterproof only when each connection point matches a catalog configuration, the cable jacket OD falls inside that part number's seal range, and termination and locking happen de-energized; an IP67 line alone does not cover an unmated port or an out-of-range cable. AC/DC assignment, pinouts, strip lengths, and torques stay with the model drawing.

De-energize first, then map the four connection points

Connector work on a horticultural lighting rig starts at the breaker, not the toolbox. Unless the model documentation explicitly permits hot-plug operation, treat every joint here as de-energized work: switch off, verify the circuit is dead, and only then touch contacts. The same applies to driver swaps — power down, and leave room around each joint for the locking movement and the cable bend. Then map the four points where waterproof connectors carry the system, because each has its own duty and its own candidate part numbers.

• Driver power input: the trunk feed; wire-to-wire suits pre-made harnesses.
• Driver to light strip: output voltage and current first, then polarity and extension length.
• Dimming and control: protocol, shielding, and grounding, not just contact count.
• Branches and distribution: one trunk, many lamps, checked per branch and at the inlet.

Sources: Technical applicability · LLT selection guide

Match part numbers to duty before stripping

Read the configuration tables per row, not per series: ratings are stated per contact for the named configuration, and a series maximum never transfers to every part number. On the driver input duty alone, the three listed 3-pin wire-to-wire options span 250 V / 15 A and 600 V / 35 A, both IP67, with a 250 V / 20 A option rated IP65 — same duty, different protection level.

The catalog tables confirm rated voltage, current per contact, conductor limits, cable OD ranges, and IP levels for the listed configurations; they do not confirm AC/DC system assignment, dimming protocol compatibility, intermateability with other brands, or model-specific torque and strip dimensions. So a 3-pin part number does not by itself confirm an L/N/PE assignment — take the pinout from the drawing — and a rating without an AC or DC mark does not cover your system by default.

Sources: LLT public connector catalog · Technical applicability

Conductor size and cable OD are two separate checks

Every table row carries a pair such as ≤ 1.5 mm² and cable Ø 3.5–8.5 mm, and the pair is not redundant. Conductor cross-section is specified in mm² per core, while cable outer diameter is the jacket OD in mm, and the OD must fall inside the seal adaptation range of the chosen part number. Two cables with identical 1.5 mm² cores can still carry different jackets, so measure the real cable and check it against the whole range — under-range cable will not be gripped or sealed either. If your documentation works in AWG, use the wire-gauge correspondence stated in the catalog rather than converting on your own.

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

Trunk and branch splits: the inlet sets the ceiling

A trunk feeding several luminaires is sized twice: once per branch, then at the inlet where branch currents add. Adding branch outlets does not raise the allowed current at the trunk inlet. Check end-of-line voltage drop too; long greenhouse rows make it worse. The listed hardware covers two maintenance styles: a T three-way junction box (3-pin, 250 V, 35 A, screw-clamp wiring, cable Ø 10–16 mm) for hard-wired splits, and a 2-pin, 250 V, 10 A overmolded distributor for pluggable drops. The distributor row lists no cable OD, so treat that as an open item, not a free pass. Number the branches, keep swap room for a faulty drop, and support every cable so no joint carries weight.

Sources: LLT public connector catalog · Technical applicability

Dimming and control: protocol before pin count

Start with the protocol — 0–10 V, DALI, or another scheme — then count what the link really carries: signal cores, auxiliary power if any, and the shield. The 8-contact dimming candidates in the tables (60 V, 110 V, or 100 V at 5 A per contact, conductors from ≤ 0.2 to ≤ 0.5 mm² depending on series) are wiring examples, not protocol certification, and not every dimming system needs eight contacts. Decide early whether dimming shares one interface with power or gets its own connector. A combined interface can be evaluated, but the contact groups are checked separately and their ratings never add. One naming trap: an LLT M12 is a series designation, not proof of intermateability with another vendor's IEC M12 A-code port. Label the control ports and cap unused interfaces.

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

Assembly order: terminate, seat the seal, then lock

If the cable jacket OD is outside the seal range listed for the part number, or the pinout drawing for the mating half is missing, stop and confirm with engineering before terminating; if both are documented and within range, continue with the assembly sequence below. The order matters because each later step hides the earlier ones — a crossed pair or a mis-seated seal is invisible once the joint is closed.

Stop if a seal is cut or missing, or if the halves do not match the drawing; neither a field repair nor a cross-brand substitution is covered by the data behind these tables.

• Verify the mating half, contact genders, and pin positions against the drawing, including the face-view direction.
• Strip and terminate per the model's own documentation; strip lengths and torques come from that document, not from habit.
• Clean the sealing faces and confirm the seal is seated and undamaged.
• Lock to the model's requirement — push-lock and threaded forms engage differently — and confirm engagement by the model's check, not appearance alone.
• Dress the cable with bend room and independent support.

Sources: LLT selection guide · Connection and wiring methods · Technical applicability

Post-assembly checks and the limits of the IP line

After locking, check the wiring against the pinout, the clamping state, and the assembly condition, then follow the project's verification flow. Cap unused ports — protection of an unmated interface is a separate question. Keep the rating honest: IP67 means dust-tight plus short-term immersion protection under specified test conditions, with the connector correctly mated and locked, seals intact, and the specified cable fitted. It is not permanent immersion, not high-pressure washdown, and not permission to mate live. If crews wash equipment, send engineering the water depth, duration, temperature, and cleaning method and choose a configuration verified for it. At commissioning, follow the luminaire's own energizing procedure rather than probing live connectors.

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

What to send engineering before you build

A complete request shortens the loop. For each connection point, send:

• Interface drawing or mating part number, contact count, and pin definition
• Working voltage and current, with AC or DC stated
• Cable length and tolerance, jacket OD, and jacket material
• Branch positions, exit directions, and end treatments
• Environment, verification needs, and target market — UL 2238, UL 1977, CE, TÜV, and SAA documents are provided per SKU

Sources: LLT selection guide · Technical applicability

Source parameters

Original table and applicability

Original table and applicability

Original table and applicability

Original table and applicability

Frequently asked questions