EGC stands for Equipment Grounding Conductor. It’s the dedicated conductive path in an electrical system that connects the metal parts of equipment, outlets, and enclosures back to the electrical panel. During normal operation, an EGC carries no current at all. Its job is purely protective: if a wire comes loose inside an appliance or a fault develops in the wiring, the EGC provides a low-resistance route for fault current to rush back to the panel and trip the breaker or blow the fuse, cutting power before anyone gets shocked.
How an EGC Protects You
Imagine a hot wire inside a metal appliance breaks free and touches the metal casing. Without an EGC, that casing becomes energized and stays that way silently. Anyone who touches it while also touching something grounded (a water pipe, a concrete floor) completes the circuit through their body. With a properly installed EGC, the fault current has a much easier path: it flows through the EGC’s low-impedance route back to the source, producing enough current to trip the overcurrent device in a fraction of a second.
The key word is “low impedance.” The EGC must offer so little resistance that fault current surges high enough to activate the breaker. A corroded connection, an undersized wire, or a broken ground path can all prevent the breaker from tripping quickly, which is why code requirements around EGC sizing and continuity are strict.
A second, less obvious function: the EGC bonds all metal components in a system together so they stay at the same voltage. This prevents a dangerous voltage difference between, say, a metal outlet box and a nearby metal pipe.
EGC vs. GEC vs. Grounded Conductor
These three terms cause endless confusion, but each one has a distinct job.
- Equipment Grounding Conductor (EGC): Runs alongside circuit wires from equipment back to the panel. Its purpose is tripping breakers during a ground fault. It’s the green or bare wire you see inside outlets and junction boxes.
- Grounding Electrode Conductor (GEC): Connects the panel’s grounding bus and neutral bus to the grounding electrode system (the ground rod, water pipe, or concrete-encased electrode buried outside your home). Its primary purpose is directing lightning strikes and power surges safely into the earth.
- Grounded Conductor: The neutral wire. It carries return current during normal operation and is typically white or gray. It is not a safety ground, even though it connects to the grounding system at the main panel.
The simplest way to keep them straight: the EGC protects people from equipment faults, the GEC protects the system from external surges, and the neutral carries everyday return current.
What an EGC Looks Like
An EGC isn’t always a wire. The National Electrical Code lists over a dozen acceptable forms. The most common ones you’ll encounter:
- Copper or aluminum wire: Bare, or insulated in green or green with yellow stripes. This is what you find inside standard Romex (NM cable) as the bare copper ground wire.
- Rigid metal conduit and intermediate metal conduit: The metal pipe itself serves as the EGC, with no separate ground wire required.
- Electrical metallic tubing (EMT): Also qualifies as an EGC on its own.
- The armor sheath of Type AC cable: The familiar metal-clad “BX” cable uses an internal aluminum bonding strip that reduces the impedance of its spiraled armor, allowing the sheath to function as the EGC.
- Type MC cable sheaths: Certain listed MC cables (like Type MCAP) use an aluminum bonding strip in contact with the metal sheath, which together serve as the EGC.
- Metal cable trays: Permitted in commercial and industrial settings when continuously maintained and properly bonded.
When the EGC is an insulated wire, code requires it to be continuously finished in green or green with one or more yellow stripes. No other conductor in the system is allowed to use those colors. If the EGC is bare copper, no color marking is needed.
How EGC Size Is Determined
The size of an EGC is based on the rating of the breaker or fuse protecting the circuit, not the size of the circuit wires themselves. The NEC provides a sizing table (Table 250.122) that specifies minimums. Here are the most common residential and light commercial values:
- 15-amp circuit: 14 AWG copper
- 20-amp circuit: 12 AWG copper
- 30-amp circuit: 10 AWG copper
- 60-amp circuit: 10 AWG copper
- 100-amp circuit: 8 AWG copper
- 200-amp circuit: 6 AWG copper
Aluminum EGCs are permitted but must be two sizes larger than the copper equivalent (for example, 12 AWG aluminum for a 15-amp circuit instead of 14 AWG copper). For very large feeders, the sizes scale up significantly: a 400-amp overcurrent device calls for a 3 AWG copper EGC, and circuits protected at 2,000 amps or above require 250 kcmil copper or larger.
These are minimums. Installers sometimes upsize the EGC to reduce impedance on long runs, ensuring the fault current stays high enough to trip the breaker quickly even at the far end of the circuit.
Bonding and Continuity Requirements
An EGC is only as good as its weakest connection. Every junction box, panel enclosure, and equipment frame along the path must be bonded to maintain electrical continuity. The NEC defines bonding as connecting parts “to establish electrical continuity and conductivity.” In practice, this means using listed grounding screws, grounding clips, or bonding jumpers at each metal box and enclosure.
If even one connection in the chain is loose or missing, the entire ground-fault current path can fail. A high-resistance joint might allow some current to flow but not enough to trip the breaker promptly. This is one of the most common wiring defects home inspectors find: an EGC that is present but not properly terminated, leaving equipment effectively ungrounded despite appearances.
When metal raceways like rigid conduit or EMT serve as the EGC, every coupling and connector must be tight and listed for grounding use. A single loose fitting can break the fault path. Flexible metal conduit has additional restrictions: it generally qualifies as an EGC only on circuits rated 20 amps or less, and only when terminated with listed fittings.
EGC in Older Homes
Many homes built before the 1960s have two-wire circuits with no EGC at all. Those ungrounded outlets (the old two-prong type) offer no ground-fault protection through an equipment ground. Replacing a two-prong outlet with a three-prong outlet without adding an actual ground path is a code violation unless GFCI protection is provided on that circuit. A GFCI device can detect a ground fault and cut power even without an EGC, but it does not provide the equipment bonding that an EGC offers.
Recent code updates have tightened requirements around retrofitting grounds in older systems. Some jurisdictions now require GFCI protection on branch circuits in specific retrofit scenarios where a full EGC isn’t being run back to the panel, adding another layer of shock protection in homes that lack modern grounding.