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.

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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

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

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

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 conductorRecord the feeder overcurrent device, conductor material, raceway type, and panel termination details before using the equipment grounding conductor sizing path.

Service upgrade grounding reviewA service upgrade may need the grounding electrode conductor path, bonding jumpers, utility requirements, and electrode system notes documented separately from branch-circuit equipment grounds.

Assumptions. Balanced load and line-to-line voltage assumptions behind this chart.

This chart is a routing worksheet and does not reproduce NEC grounding conductor tables.
Grounding and bonding requirements can change with service equipment, separately derived systems, electrodes, utility requirements, and local amendments.
Wire size does not replace bonding continuity, termination listing, corrosion review, or inspection requirements.

Code and standard notes. Planning limits that should be checked before final equipment selection.

Verify grounding and bonding with the adopted NEC edition, equipment listing, manufacturer instructions, utility requirements, local amendments, and the Authority Having Jurisdiction (AHJ).
Grounding electrode conductors, equipment grounding conductors, bonding jumpers, and supply-side bonding conductors are not interchangeable paths.

How to use this chart

1Name the grounding pathSeparate equipment grounding conductors, grounding electrode conductors, bonding jumpers, and separately derived system questions before choosing a sizing method.

2Record the controlling valueThe overcurrent device, service conductors, transformer secondary, electrode type, utility requirement, and conductor material can point to different review paths.

3Check continuity detailsAfter the calculator result, document lugs, jumpers, fittings, raceways, enclosures, corrosion exposure, and bonding hardware that complete the fault path.

Worksheet checklist. Record source basis, review gaps, and assumptions before using the chart result.

Identify conductor purposeWrite whether the conductor is for equipment grounding, bonding, grounding electrode connection, or separately derived system work.
Record source ratingDocument the upstream overcurrent device, service conductor size, transformer secondary, or electrode condition that controls the calculation path.
Close the bonding reviewCheck metallic raceways, enclosures, jumpers, lugs, corrosion conditions, utility notes, and AHJ requirements before treating the size as ready for installation.

Common mistakes to avoid. Review these before turning chart current into an equipment decision.

Using one ground wire chart for every grounding and bonding question even though different conductor purposes use different paths.
Ignoring raceway bonding, enclosure continuity, termination listing, corrosion exposure, or local amendments after selecting a conductor size.
Treating a grounding electrode conductor result as if it also sizes every equipment grounding conductor in the distribution system.

Frequently asked questions

These answers explain how to use the chart without turning a quick reference into a final design decision.

Is every ground wire sized from the breaker?

No. Equipment grounding conductors often use the overcurrent device as a key input, but grounding electrode and bonding paths can use different controlling values.

Why does bonding matter after choosing a wire size?

Continuity through raceways, enclosures, fittings, jumpers, and terminations is part of the fault path. Wire size alone does not prove the installation is complete.

Can grounding electrode conductors and equipment grounding conductors be treated the same?

No. They serve different purposes and can follow different sizing inputs, so the worksheet keeps the conductor purpose explicit.