The ground wire that runs with your circuit (the equipment grounding conductor, or EGC) is primarily sized by your breaker rating, with some exceptions such as voltage-drop adjustments. A 20-amp breaker needs a #12 AWG copper EGC. A 100-amp breaker needs a #8 AWG. A 200-amp feeder needs a #6 AWG. The full chart, plus when you have to go bigger, is below.
This guide covers EGC sizing only — the green or bare ground wire that bonds your equipment back to the panel. It does not cover the GEC (the wire that goes from your service to the ground rod). Those are two different conductors with two different rules, and we’ll explain the difference at the end.
Note on code edition: The 2026 NEC has been published by NFPA, but adoption varies by state. Many U.S. jurisdictions are still enforcing the 2023 or even 2020 edition. Always verify the version adopted in your area before installation.
What an EGC Actually Does
An EGC sits idle until something goes wrong. When a hot wire touches a metal enclosure, the EGC carries that fault current straight back to the panel and forces the breaker to trip. No EGC, or an undersized one, means the metal stays energized and waits for someone to touch it.
Three things to remember:
- It carries fault current only, not normal load current.
- Its job is to trip the breaker quickly, not to handle continuous amps.
- Larger breakers require larger EGCs to ensure sufficient fault current flows to trip the breaker quickly.
Source: NEC 2026, Section 250.4, “General Requirements for Grounding and Bonding.” (NFPA 70, National Electrical Code, 2026 Edition.)
Changed in 2026 NEC: Article 250 now covers only systems not over 1000V AC / 1500V DC. Higher-voltage rules moved to the new Article 270. This article focuses on standard residential, commercial, and light industrial work, which all stay under Article 250.
EGC Ground Wire Sizing Chart
Here’s the full NEC ground wire size chart. Find your breaker rating in the left column, then read across to copper or aluminum.
| Breaker / OCPD Rating Not Exceeding (Amps) | Copper EGC (AWG / kcmil) | Aluminum or Copper-Clad Aluminum EGC (AWG / kcmil) |
| 15 | 14 AWG | 12 AWG |
| 20 | 12 AWG | 10 AWG |
| 60 | 10 AWG | 8 AWG |
| 100 | 8 AWG | 6 AWG |
| 200 | 6 AWG | 4 AWG |
| 300 | 4 AWG | 2 AWG |
| 400 | 3 AWG | 1 AWG |
| 500 | 2 AWG | 1/0 AWG |
| 600 | 1 AWG | 2/0 AWG |
| 800 | 1/0 AWG | 3/0 AWG |
| 1000 | 2/0 AWG | 4/0 AWG |
| 1200 | 3/0 AWG | 250 kcmil |
| 1600 | 4/0 AWG | 350 kcmil |
| 2000 | 250 kcmil | 400 kcmil |
| 2500 | 350 kcmil | 600 kcmil |
| 3000 | 400 kcmil | 600 kcmil |
| 4000 | 500 kcmil | 750 kcmil |
| 5000 | 700 kcmil | 1250 kcmil |
| 6000 | 800 kcmil | 1250 kcmil |
Based on NEC 2023 Table 250.122 (values unchanged in later editions as of this writing). Adapted from NFPA 70, National Electrical Code, “Minimum Size Equipment Grounding Conductors for Grounding Raceway and Equipment.” Full code text available at nfpa.org.
A few quick notes on reading the chart:
- These are minimums. Going larger is always allowed.
- Aluminum is always one to two AWG steps bigger than copper for the same breaker.
- Under NEC minimum requirements, the EGC is not required to be larger than the circuit conductors.
For sizing the load-carrying conductors that run alongside the EGC, see our separate wire size calculator and the house wiring cable size guide.
How to Choose the Right Ground Wire Size
Three steps, in order. Skip step 3 only if your run is short and straightforward.
Step 1 — Find your breaker size. This is the rating of the circuit breaker or fuse protecting the circuit. Not the load amps, not the hot wire ampacity. Just the OCPD rating.
Step 2 — Look it up in the chart. Read across to the copper or aluminum column. If your exact breaker rating isn’t listed, use the next higher standard rating shown in Table 250.122.
Step 3 — Decide if you need to upsize. You upsize if any of these apply:
- You made the hot wires bigger to fight voltage drop on a long run.
- You’re running parallel feeders in separate conduits.
- It’s a motor circuit (special rule — see below).
If none apply, you’re done. Pull what the chart says.
When You Have to Upsize the EGC
You must upsize the EGC whenever you upsize the hot conductors for voltage drop. The ground wire has to grow by the same proportion as the hot wires, measured in circular mils. This is required by NEC 2026, Section 250.122(B).
Here’s a real example. A 60A subpanel feeds a workshop 150 feet away.
- Normal phase conductors for 60A: #6 AWG copper.
- Normal EGC from the chart: #10 AWG copper.
- To handle the long run, you upsize the phase conductors from #6 AWG (26,240 cmil ) to #4 AWG (41,740 cmil ). That’s a 1.59× increase.
- Apply the same 1.59× to the EGC. #10 AWG (10,380 cmil ) × 1.59 = 16,505 cmil needed.
- The next standard size up is #8 AWG (16,510 cmil ).
Circular mil values come from NEC, Chapter 9, Table 8.
One thing to note: if you only upsized the hot wires for ambient temperature or conduit fill (not voltage drop), the EGC does not have to grow. That rule has carried over unchanged from the 2020 and 2023 cycles into 2026.
Quick Recap
The ground wire that runs with your circuit is sized by the breaker rating, not the load. Use NEC Table 250.122, pick copper or aluminum, and upsize proportionally if you stretched the hot wires for voltage drop. For most residential and light commercial work, the chart is the entire answer.
If you’re sourcing wire and cable for the job, APS Cable carries THHN building wire, MC cable, and tray cable assemblies with NEC-compliant equipment grounding conductors built in.
All chart values, code references, and circular-mil calculations in this article are sourced from NFPA 70, National Electrical Code, 2026 Edition (published by the National Fire Protection Association). Always verify against the edition adopted in your jurisdiction before performing installation work.
