NEC ReferenceNEC 2023 · 2026 · Updated Apr 2026

NEC Article 250: Grounding and Bonding

NEC Article 250: Grounding & Bonding covers vs bonding through bonding of metal piping. This guide explains each major section with practical interpretation for electricians.

Grounding vs Bonding

Grounding connects the system to earth (for lightning and voltage stabilization). Bonding connects all metal parts together (to ensure fault current has a low-impedance path back to the source so the breaker trips). Bonding is actually more important for safety - a ground rod alone will not trip a breaker during a fault.

250.122 Equipment Grounding Conductor (EGC)

The EGC (green or bare wire) carries fault current back to the panel. Sized by the breaker rating: 15A = 14 AWG, 20A = 12 AWG, 30A = 10 AWG, 40A = 10 AWG, 60A = 10 AWG, 100A = 8 AWG, 200A = 6 AWG copper. Must increase if wire is upsized for voltage drop.

250.66 Grounding Electrode Conductor (GEC)

The GEC connects the panel to the grounding electrode. Sized by the largest service conductor: up to 2 AWG service = 8 AWG GEC, 1 AWG or 1/0 service = 6 AWG GEC, 2/0 or 3/0 service = 4 AWG GEC, over 3/0 through 350 kcmil = 2 AWG GEC, over 350 through 600 kcmil = 1/0 AWG GEC, over 600 through 1100 kcmil = 2/0 AWG GEC, over 1100 kcmil = 3/0 AWG GEC copper.

250.52-56 Grounding Electrodes

Grounding electrodes in order of preference: concrete-encased (UFER) - 20+ feet of #4 rebar in footing, metal water pipe (first 5 feet entering building), ground rod(s) - 8 feet driven, two required unless one measures under 25 ohms, building structural steel.

250.104 Bonding of Metal Piping

Metal water piping, gas piping, and other metal piping systems must be bonded. Water pipe bonding: sized per Table 250.66. Gas pipe bonding: sized per Table 250.122 (EGC size for the circuit likely to energize the pipe). Metal CSST gas pipe requires bonding per manufacturer instructions.

Key NEC Tables Referenced

Frequently Asked Questions

What does NEC Article 250 cover?

Article 250 covers grounding & bonding requirements. Key sections include Grounding vs Bonding and 250.122 Equipment Grounding Conductor (EGC). It applies to all electrical installations in the United States.

Where can I find the full text of Article 250?

The full NEC is published by NFPA and available at nfpa.org. Many libraries provide free access. Your local building department also has copies available for reference during permit applications.

Does Article 250 apply to existing wiring?

The NEC applies to new installations, modifications, and additions. Existing wiring that was code-compliant when installed is generally grandfathered unless a renovation triggers an upgrade requirement. Check with your local AHJ (authority having jurisdiction).

When did the current Article 250 requirements take effect?

NEC 2023 is the current edition. Adoption varies by state. Check your state adoption status on our state code pages.

Requirements vary by state. NEC edition, licensing, permits, and GFCI rules differ by jurisdiction. Check your state or pick it below for personalized info across WireRef.
This guide provides practical interpretation of NEC requirements. Always verify with your local AHJ and the current NEC edition adopted in your jurisdiction. WireRef is a reference tool and does not replace licensed professional judgment.

NEC 2023 references verified April 2026