Installation_
Containment & Pathway Build-Out for a GPU Row
Details the exact sequence for installing overhead trays, aisle containment, and fiber pathways in a GPU row so that cabling crews can pull and terminate MPO trunks without rework or blocked access.
Key facts
- TIA-942 requires separate pathways for fiber and power with separation in data halls.
- Factory-terminated MPO trunks must be pulled after tray supports are load-rated and grounded per manufacturer torque values.
- Aisle containment attaches to rack tops only after overhead tray sections are fully bolted and leveled.
- Fiber trunks route in dedicated ladder sections separate from copper NVLink backplanes inside each rack.
- OTDR testing occurs after all pathway supports are complete and before any rack power-up.
- BICSI TDMM recommends pulling fiber before final door and panel installation to avoid pinch points at containment seals.
- Leviathan Systems sequences tray and containment work ahead of scale-out fiber crews on all NVL72-class deployments.
Row alignment verification before any overhead work
Confirm rack footprints sit on the exact floor grid with front-to-front aisle widths matching the containment kit drawings. Measure diagonal distances between opposite racks at both ends of the row; any deviation beyond the OEM tolerance forces tray brackets out of plumb later.
Verify that liquid cooling manifolds and busway drops are already terminated and pressure-tested. This order prevents tray installers from working over live or pressurized lines and gives cabling crews clear vertical access once trays are in place.
Overhead tray installation and load verification
Mount ladder sections to the overhead structure using the pre-drilled support points shown on the reflected ceiling plan. Torque all hanger rods to the values listed on the tray manufacturer drawing before hanging the next section; this keeps the run level and prevents cumulative sag that would later bind MPO pulls.
Ground each tray section to the row bonding grid with the specified conductor size. Run a continuity check end-to-end before any cable is placed. Separate fiber ladder sections from power trays by the distance required in TIA-942 so that later MPO work stays isolated from electrical crews.
Aisle containment frame attachment sequence
Bolt the containment frame uprights to the top of each rack only after the overhead trays above that bay are fully supported and leveled. Attaching containment first creates fixed vertical planes that block tray adjustment and force later fiber pathway offsets.
Install the horizontal cross members and seal strips next. Leave the end-of-row doors and sliding panels off until all trunks are routed; this keeps the aisle open for cable carts and prevents repeated removal of containment seals during testing.
Dedicated fiber pathway routing for scale-out trunks
Pull MPO trunks through the designated fiber-only ladder sections after tray grounding is verified. Because NVLink connections inside NVL72 racks use copper backplanes, the MPO trunks carry only the InfiniBand or Ethernet scale-out fabric between leaf switches and core layers.
Support each trunk with approved radius-limiting brackets at every transition and maintain the minimum bend radius shown on the cable datasheet. Label both ends with the port mapping before the cable leaves the reel so that later patching crews can locate runs without opening containment.
Common sequencing failures and field checks
The most frequent error is installing full containment before trays are complete, which forces fiber crews to work around fixed walls and creates pinch points at every seal. Catch this by requiring a signed pathway release form from the tray crew before containment panels are staged.
Another recurring issue is tray sections left ungrounded until after fiber is pulled; induced voltage then appears during OTDR testing. Require the bonding megger reading to be logged before the first trunk enters the tray. A third failure occurs when cooling drip pans are hung after trays, cutting off access to the fiber pathway; enforce a vertical clearance check against the manifold drawings before tray bolting begins.
Final pathway inspection before cabling handoff
Walk the row with an OTDR and a calibrated MPO continuity tester after all supports are complete. Record baseline traces for every trunk while the aisle is still open; any later containment work risks disturbing the cables and invalidating the baseline.
Confirm that all tray sections remain accessible from the aisle side and that no power or cooling lines cross the fiber pathway. Sign the pathway completion tag only when these conditions are met so that the termination crew can begin work without waiting on other trades.
Standards referenced: TIA-942 · BICSI TDMM
Frequently asked_
When should aisle containment doors be installed relative to MPO trunk pulls?
Leave doors and end panels off until after all trunks are routed and tested. Installing them early creates fixed barriers that require repeated removal during cable placement and OTDR work. The open aisle also lets cable carts move freely without lifting trunks over containment seals.
How do you keep fiber pathways clear of NVLink copper runs inside the rack?
Route MPO trunks exclusively in the overhead fiber ladder sections; the copper NVLink spine stays inside each rack on its dedicated backplane. Never attempt to combine the two media in the same pathway, because the physical layer requirements and test procedures are completely separate.
What check must pass before the fiber crew begins pulling?
All tray sections must be leveled, grounded, and load-verified with a signed release from the tray crew. Containment frames can be attached but doors must remain off. These steps eliminate the need to disturb installed trunks later when adjustments are discovered.
Who typically coordinates the sequence on large GPU row projects?
Leviathan Systems assigns a single pathway lead who holds the release forms for each trade. The lead verifies tray grounding and level before allowing containment attachment, then confirms open access before releasing the row to the fiber termination crew.