Equipment Grounding Conductor Calculation

PLANNING SIZE

2023 NEC reference — narrow planning scope

This calculator addresses one wire-type EGC in one non-parallel raceway through 600 A. Verify the adopted code, effective ground-fault-current path, wiring method, material restrictions, special equipment rules, taps, motors, and AHJ requirements.

Calculation inputs

Circuit and conductor sizes

Project information for worksheet

Project nameCircuit identifierPrepared byRevision

Overcurrent protection — ASelect the rating or setting of the automatic overcurrent device.Phase conductor materialMinimum phase conductorThe smallest phase conductor with sufficient ampacity for the intended installation.Installed phase conductorUse the final size after voltage-drop or project upsizing.Phase constructionPhase conductor quantityEnter all insulated phase/ungrounded conductors that will be transferred to conduit fill.Equipment grounding conductor materialEGC construction

Transparent calculation

How the grounding size was selected

Base table size

12 AWG

Copper EGC for an overcurrent device not exceeding 20 A.

Phase-conductor increase

× 1

12 AWG installed area ÷ 12 AWG minimum area.

Required EGC area

6,530 cmil

6,530 cmil × 1.

Final standard size

12 AWG

Next supported conductor area meeting or exceeding the calculated requirement.

Continue this calculation

Send these inputs to another calculator

The destination opens with compatible conduit and cable inputs already selected. This calculator and its results remain unchanged.

Continue both conductors to Conduit SizeTransfers 3 phase conductors and one EGC as separate product-selection rows.Open calculator →Continue both conductors to Conduit FillSelect the exact insulation and manufacturer product for each row so verified outside diameters are used.Open calculator →

Method and scope

What this result establishes

The result reproduces the supported portion of 2023 NEC Table 250.122 and applies proportional circular-mil adjustment when the installed phase conductor is larger than the entered minimum.

Required verification

What remains outside this calculator

It does not determine the overcurrent device, phase-conductor ampacity, raceway-as-EGC suitability, fault-current performance, parallel-raceway rules, motor or tap provisions, material installation restrictions, or final code compliance.