Electrical reference chart
Ground Wire Size Chart
Use this ground wire size chart after the calculator result to document which grounding path was used, what rating controlled it, and what bonding details remain before inspection.
Quick reference table
Ground wire size depends on the purpose of the conductor. Equipment grounding conductors, grounding electrode conductors, bonding jumpers, and supply-side bonding conductors can use different inputs, so the calculator result must be tied to the correct path and then verified with the adopted NEC edition, utility requirements, equipment data, and AHJ review.
Grounding path selection chart
| Question on the job | Likely worksheet path | Record first |
|---|---|---|
| Feeder or branch circuit equipment ground | OCPD-based equipment grounding conductor review | Upstream breaker or fuse rating and conductor material |
| Service grounding electrode conductor | Service grounding electrode conductor review | Service conductor data, electrode type, and utility context |
| Separately derived system | Transformer or derived system grounding review | Secondary conductors, bonding point, and equipment instructions |
| Bonding jumper | Bonding continuity review | Raceway, enclosure, fittings, and fault-current path |
| Existing grounding repair | Diagnostic and correction worksheet | Measured condition, corrosion, missing jumpers, and layout |
Result-area grounding checks
| Calculator result shows | Do not forget | Why it matters |
|---|---|---|
| EGC size based on OCPD | Raceway and enclosure bonding | Wire size alone does not prove a continuous fault path |
| GEC size based on service data | Electrode system and service equipment layout | The grounding electrode path is different from branch-circuit grounding |
| Aluminum grounding conductor | Location, termination listing, and corrosion environment | Material choice can be restricted by installation conditions |
| Bonding jumper selected | Fittings, concentric knockouts, and bonding bushings | Mechanical continuity can be the weak point |
How to use this chart
Name the grounding path
Separate equipment grounding conductors, grounding electrode conductors, bonding jumpers, and separately derived system questions before choosing a sizing method.
Record the controlling value
The overcurrent device, service conductors, transformer secondary, electrode type, utility requirement, and conductor material can point to different review paths.
Check continuity details
After the calculator result, document lugs, jumpers, fittings, raceways, enclosures, corrosion exposure, and bonding hardware that complete the fault path.
Formula basis
Grounding conductor selection = identify conductor purpose, controlling rating, conductor material, and installation path before applying the adopted sizing rule.
- Conductor purpose determines whether the worksheet follows an equipment grounding, grounding electrode, or bonding path.
- Controlling rating may be an overcurrent device, service conductor, transformer secondary, or electrode condition.
- Material, termination, and bonding continuity affect the final installation review.
Worked examples
Panel feeder equipment grounding conductor
Record the feeder overcurrent device, conductor material, raceway type, and panel termination details before using the equipment grounding conductor sizing path.
Service upgrade grounding review
A service upgrade may need the grounding electrode conductor path, bonding jumpers, utility requirements, and electrode system notes documented separately from branch-circuit equipment grounds.
Related calculators
GEC Sizing Calculator
Screen grounding electrode conductor sizing from Table 250.66, equivalent parallel service-conductor area, and electrode-specific practical caps.
Circuit Breaker Sizing Calculator
Calculate standard breaker sizes for general loads, continuous loads, and simplified motor branch-circuit reviews
Grounding Calculator
NEC Article 250 grounding and bonding conductor screen for main bonding jumpers, equipment grounding conductors, and grounding electrode conductors.
Related charts
Wire Size Chart
Screen conductor size from calculated load, copper or aluminum material, terminal rating, derating, voltage drop, and equipment notes.
Ampacity Chart
Review conductor ampacity as a heat problem: material, insulation, terminal rating, ambient correction, bundling adjustment, and equipment limits.
Box Fill Chart
Plan box fill from conductors, devices, internal clamps, equipment grounds, fittings, pigtails, and marked box volume.
Frequently asked questions
These answers explain how to use the chart without turning a quick reference into a final design decision.