Fixture Placement
& Orientation
Exact positioning for 4×4 and 5×5 footprints — perpendicular vs parallel layouts, spacing, height, and daisy-chain routing for balanced under-canopy light.
Table of Contents
Section 4:
Physical Setup and Placement
This section gets the hardware in the right spot the first time. The goal is even lower-canopy coverage without blocking irrigation, airflow, or workflow.
Layout planning
- Map the rows and aisles
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- Sketch each table or footprint with plant count and aisle widths.
- Note emitters, drain paths, stakes, and trellis anchor points. Fixtures must not block any of these.
- Choose fixture orientation
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- Perpendicular to tables (recommended): Run fixtures across the short axis so lenses face into the plant rows. This keeps aisles clear for access to pots, improves cross-row uniformity, and has shown better light spread and yield. When using perpendicular runs, connect fixtures with daisy-chain cables along the bench frame so each cross-run links to the next without crossing wet zones.
- Parallel to tables: Use when infrastructure or trellis paths require it. Keep lenses horizontal and offset to eliminate bright stripes. Verify uniformity with a quick visual pass or meter spot checks.
- Target coverage zones
- Under-canopy light should cover the lowest third of foliage and interior branch sites.
- Avoid hot windows aimed at a single stem or cola.
Footprint and Starting Layout
- Two Tri-Spec per 4×4 or 5×5 area.
- Divide the area into three even sections. With 16 plants (4 rows × 4 plants), place one fixture between rows 1 & 2 and one between rows 3 & 4.
- Perpendicular to tables gives best spread and access; parallel is acceptable.
- Start height: ~14 in below canopy (range 8–20 in). Maintain gentle airflow across the lower canopy.
Mounting height and spacing
- Mounting height window: ≈ 14 in below canopy (starting point within an 8–20 in range).
- If internodes are very tight or foliage is dense, drop to 10 to 12 inches for better penetration.
- If plants are sparse or sensitive, raise to 16 to 18 inches and use lower output.
- Fixture-to-plant clearance: Keep at least 6 inches of air gap from the nearest leaf at all times. Re-check after defoliation and bulking.
Stands, straps, and stability
- Use the height-adjustable under-canopy stand or rigid, non-conductive crossbars.
- If strapping to frames, use UV-stable straps and lock them so fixtures cannot slide during turns or irrigation pulls.
- Do not rest fixtures directly on cultivation tables. Maintain airflow and splash protection.
Cable routing and water management
- Route cabling along frame members, then down the dry side of the table.
- Form drip loops before every connector. Keep connectors above the flood line and away from drain paths.
- Label each run by bay and sequence for fast service.
- Keep cords out of aisles. If a crossing is unavoidable, use low-profile cable ramps.
Daisy-chain and power planning
- In perpendicular layouts, use daisy-chain cables to hop fixture-to-fixture across the footprint, then drop to the dry side for mains.
- Use the shortest daisy-chain length that reaches without tension.
- Group fixtures so a single circuit shutoff isolates one work area.
- Stay within the published daisy-chain limit for the fixture and voltage you are using.
- Balance circuits across phases. Use GFCI where required. Keep power supplies and junctions high and dry.
Airflow protection
- Verify a clear path for gentle airflow across the lower canopy. The fixture should not block fan streams or push leaves into emitters.
- If leaves flutter against the lens, redirect fans or raise the fixture.
Verification before power-up
- Wipe lenses with a clean, lint-free cloth. Dust reduces output and can cause micro hot spots.
- Confirm every connector is fully seated, elevated, and drip-looped.
- Push-test mounts and stands. Nothing should sway or rattle.
- Run fans and irrigation without lights to confirm no spray reaches lenses or connectors.
First-week adjustment playbook
- Day 0: Commission at about 50 percent on the Full+Red channel only. Walk both sides of the footprint and look for bright stripes or dark lanes. Adjust lateral position to even the wash.
- Day 1 to 2: After defoliation or tuck, re-check leaf clearance. Raise fixtures if any leaves sit within 6 inches of the lens.
- Day 3 to 4: If lowers look flat or shadowed, lower the fixture by 1 to 2 inches or move it toward the darkest lane. If edges look dry or tips nip, raise 2 inches or reduce intensity 10 to 20 percent.
- Day 5 to 7: Lock placement. Only after stability should you introduce Far-Red pulses and, later, UV windows.
- After 7 stable days, you may progress to the Aggressive Profile (Section 15).
Do and Don’t checklist
Do
- Prefer perpendicular orientation where possible for access and spread.
- Use two fixtures in any 4×4 or 5×5 area.
- Keep lenses horizontal and maintain 8 to 20 inches below canopy with 6 inches minimum clearance from leaves.
- Use drip loops and keep connectors above splash height.
- Verify airflow across the lower canopy after placement and re-check after every major tuck or defol.
- Daisy-chain perpendicular runs fixture-to-fixture, then exit on the dry side.
Don’t
- Do not point lenses into aisles or up toward mid-canopy.
- Do not block emitters, drain lines, or trellis pathways.
- Do not run cables across wet zones or leave them loose in aisles.
- Do not bring fixtures within 6 inches of leaves.
- Do not change placement and spectrum on the same day.
When the physical setup is locked, you are ready for Section 5: Power-Up and Commissioning.