IT-04
Rack Builder (EIA-310-E)
EIA-310-E · ASHRAE thermal guidelines · ANSI/BICSI 007-2024 · NEC 310.15(B) · IEC 62040-3
Drawing
The drawing appears when the inputs are complete
- 01Lay out an equipment rack to EIA-310-E: rack unit occupancy with ventilation gaps, weight and centre of gravity, depth clearance, floor loading, power and heat roll-up.
- 02Tip. Load the heaviest items lowest. The centre of gravity is what decides whether a rack tips when it is moved on castors or when an item is pulled out on rails, and it is the one figure a rack elevation drawing never shows.
- 0344.45 mm — 1 rack unit
- 04482.6 mm — 19" panel width
- 0545 U — Tallest standard rack
- 0625 % — Spare capacity target
- 0750 % — Centre of gravity limit
EIA-310-E rack geometry
EIA-310-E fixes the dimensions every 19-inch rack and every rack-mount product is built to. A rack design succeeds or fails on four budgets — space, weight, depth and heat — and all four are set before any equipment is ordered.
Space and ventilation
Equipment is counted in rack units, with gaps inserted where a device needs side or convection ventilation. Spare capacity is what absorbs the changes that arrive after handover.
Use cases
- 1 U = 44.45 mm (1.75 in)
- 19 in full width, 9.5 in half width
- Standard heights 8 U to 45 U
- 25 % spare capacity is the usual planning target
Formula
Occupied U = equipment U + ventilation gaps + reserved zones
EIA-310-E
Weight and centre of gravity
Total mass drives floor loading; where that mass sits decides stability. A rack loaded top-heavy can tip when moved on castors or when a heavy item is pulled out on rails.
Use cases
- Heaviest items lowest, always
- Centre of gravity at or below half height
- Check floor loading against the structural drawings
- Depth must clear cable bend radius at the rear
Formula
CoG = Σ(item mass × item centre height) ÷ Σ(item mass)
Target ≤ 50 % of rack height
Heat is the fourth budget and the one most often left to someone else. Every watt drawn by the equipment in the rack is rejected into the room as heat; carry the total from here into the rack cooling calculation rather than estimating it again.
- 01Rack dimensions and rack units — EIA-310-E
- 02Equipment room cooling — ASHRAE thermal guidelines
- 03ICT design for intelligent buildings — ANSI/BICSI 007-2024
- 04Conductor ampacity and derating — NEC 310.15(B)
- 05UPS classification and runtime — IEC 62040-3