RACEWAY · REFERENCE GUIDE
Conduit and cable tray sizing
Reference guide to conduit and cable tray sizing: 3 checks to work through, the limits that apply and when to verify against the NEC and maker data.
US (NEC) only · NFPA 70 / NEC — locally adopted editionDefaults are US values. Verify the locally adopted NEC edition and project data.Official reference ↗
REFERENCE GUIDE
Before starting
- Use the conduit fill calculator for round conduits using actual outside cable diameters.
- Cable tray fill depends on tray type, depth, cable construction and local rules.
- Separate mechanical fill from thermal derating and maintain manufacturer bend radii.
This is a reference guide, not a sizing calculator or installation approval.
Method & assumptions
Reference workflow — project-specific verified data required
This is a reference guide, not a sizing calculator or installation approval.
Results do not check every aspect of an electrical installation. The calculators follow US (NEC) practice only; a regional preset changes defaults such as voltage and units, and no result certifies NEC compliance.
Sources and validation →Estimating and invoicing tool
Ampxa is developing an estimating and invoicing application for electrical contractors. The list below receives notice when it opens.