
Cable Tray Fill Calc
NEC Cable Tray Fill Tool
0 ratings
$4.99
About
Built for electricians, cable-tray installers, and EEs who need a quick NEC 392 fill check on the deck - not a dashboard you log into.
WHAT IT DOES
Computes total cable cross-section as a percentage of tray area and compares against the NEC 392 maximum fill: 50% for ladder and wire-basket trays, 40% for solid-bottom and channel trays. Flags over-fill and shows how many more cables of the same type fit before the limit.
INPUTS
- Unit system: SAE (inches) or Metric (mm)
- Tray type: Ladder, Solid Bottom, Wire Basket, Channel
- Tray size: 9 imperial sizes / 9 metric sizes
- Cable type: AWG #14 to 4/0 (SAE) or 1.5 to 50 mm² (Metric)
- Cable count
RETURNS
- Tray area (sq in or sq mm)
- Total cable area (sq in or sq mm)
- Fill percentage
- Maximum allowed fill per NEC 392 (50% or 40% depending on tray type)
- Remaining capacity in number of cables
- Over-fill warning (red banner) when above the allowed percentage
WHY THIS APP, NOT THE FREE ONES
- Math is shown - tray area, total cable area, and the percentage all visible.
- NEC 392 fill limits applied automatically - pick the tray type and the cap follows.
- Works offline - basements, riser shafts, mid-deck rough-ins. Always available.
- No login. No ads. No telemetry. No subscription.
PRICING
$4.99. Pay once, own it. Lifetime access on iPhone, iPad, and Mac via Family Sharing.
NOT A SUBSTITUTE FOR
AHJ-stamped electrical drawings. Manufacturer cable-tray load tables. NEC 392 ampacity derating for closely-spaced multiconductor cables - this app handles cross-section fill only, not the temperature derate. Always cross-reference the engineer-stamped layout.
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What's New in Cable Tray Fill Calc
1.0.2
June 30, 2026
Added a More Pro Tools section to discover related field calculators.


