NEC Reference Library

Sizing for supply-side, main, and system bonding jumpers based on largest ungrounded conductor.

Minimum EGC sizes based on overcurrent protection rating. Includes proportional increase rules.

Sizing for service grounding electrodes, water pipes, and structural steel connections.

Fast reference for common residential and commercial trench depths and cover rules.

Comprehensive cover requirements for all wiring methods and locations (0 to 1000 Volts).

Multipliers for ampacity based on ambient temperature variations.

Mandatory derating factors for raceways containing more than three current-carrying conductors.

High-speed reference for common Copper and Aluminum wire sizes (60°C to 90°C).

The master NEC ampacity table for all insulated conductors and terminal temperature ratings.

Maximum conductor counts for standard square, switch, and handy metal boxes.

Per-conductor cubic inch volume requirements used for calculating non-standard box fill.

Internal area and 40% fill capacity for Electrical Metallic Tubing (EMT).

Area and conductor capacity specifically for Rigid PVC Schedule 40 raceways.

Capacity limits for heavy-wall Schedule 80 PVC (accounts for reduced internal area).

Internal dimensions and wire fill limits for Rigid Metal Conduit (RMC).

Resistance and reactance values for voltage drop math and stranded conductor areas.