PROTECTION · REFERENCE GUIDE
Conductor and protective device coordination
Reference guide to conductor and protective device coordination: the checks to work through and when to verify against the NEC and the manufacturer's 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
- Record design current, cable installation method and corrected ampacity.
- Confirm protective-device rating, interrupting capacity and time-current curve.
- Check fault-loop disconnection and cable I²t against manufacturer let-through data.
- Document selectivity with upstream protection; this page does not determine coordination.
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.