Grounding Size Calc NEC

About this app

NEC grounding size calculator for electricians, apprentices, and electrical engineers. Three calculators in one app: Equipment Grounding Conductor (EGC) from Table 250.122, Grounding Electrode Conductor (GEC) from Table 250.66 with sole-connection exceptions, and Bonding Jumper from Table 250.102(C)(1) with the 12.5% rule. Works 100% offline on the job site. Whether you're sizing an EGC for a 200A circuit, determining the GEC for a 500 kcmil service with a ground rod electrode, or calculating a bonding jumper for parallel service conductors, this calculator gives you accurate NEC-compliant results in seconds. THREE CALCULATORS IN ONE: EQUIPMENT GROUNDING CONDUCTOR (EGC): - Size EGC per NEC Table 250.122 - all 21 table rows from 15A to 6000A - All 37 standard OCPD ratings per NEC 240.6(A) selectable - including 30A, 40A, 50A, 70A, 125A - Copper and aluminum conductor support - Voltage drop adjustment per NEC 250.122(B) - proportionally increase EGC when circuit conductors are upsized - Original and adjusted wire size selection for accurate proportional calculation - Automatic rounding up to next standard OCPD rating GROUNDING ELECTRODE CONDUCTOR (GEC): - Size GEC per NEC Table 250.66 based on service conductor size - Support for copper and aluminum service conductors - Parallel sets calculation (1-6 sets) with automatic equivalent area computation - Sole-connection exceptions per NEC 250.66(A), (B), and (C): - 250.66(A): Rod, pipe, or plate electrode - GEC capped at #6 Cu / #4 Al - 250.66(B): Concrete-encased electrode - GEC capped at #4 Cu / #4 Al - 250.66(C): Ground ring - GEC capped at #2 Cu / #2 Al - Five electrode types: Water Pipe, Rod/Pipe/Plate, Concrete-Encased, Ground Ring, Other BONDING JUMPER: - Size bonding jumpers per NEC Table 250.102(C)(1) - Same ranges as Table 250.66 for conductors within table limits - Automatic 12.5% rule for service conductors exceeding 1100 kcmil Cu or 1750 kcmil Al - Parallel sets support with combined circular mil area calculation CALCULATION RESULTS INCLUDE: - Conductor size in AWG or kcmil with alternative material - Exception applied with NEC section reference - NEC article references for every result - Detailed notes for parallel sets and electrode exceptions NEC REFERENCES INCLUDED: - NEC Table 250.122 - Equipment grounding conductor sizing - NEC 250.122(B) - EGC increase for voltage drop - NEC Table 250.66 - Grounding electrode conductor sizing - NEC 250.66(A) - Rod, pipe, or plate electrode exception - NEC 250.66(B) - Concrete-encased electrode exception - NEC 250.66(C) - Ground ring exception - NEC Table 250.102(C)(1) - Bonding jumper sizing - NEC 250.102(C)(1) - 12.5% rule for large conductors PRO FEATURES (one-time purchase): - No ads - clean interface for professionals - Save grounding calculation history with labels - Export calculations as PDF reports for permits and records - Dark theme support PERFECT FOR: - Licensed electricians sizing grounding conductors daily - Electrical apprentices and journeyman exam preparation - Electrical engineers specifying grounding systems - Electrical inspectors verifying conductor sizes OFFLINE & PRIVACY: - Works 100% offline - no internet needed on the job site - No account required - No data collection - your calculations stay on your device Simplify your grounding and bonding calculations on the job site.

What's new: • Complete NEC Table 250.122 catalog — added 30A and 40A rows (all 21 rows covered) • All 37 standard OCPD ratings per NEC 240.6(A) selectable: 25A, 50A, 70A, 90A, 125A, 175A and more • Copper-only guidance for concrete-encased electrode connections per 250.66(B) Thanks for using ElecTools! Send feedback to support@tradetools.dev.

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1. First observed Oct 16, 2026 · 4:59 PM $0.99