An EGC, or equipment grounding conductor, is a safety component in your electrical system that connects the metal parts of outlets, junction boxes, appliances, and other equipment back to the grounding system. Its entire purpose is to provide a path for electrical current to follow if something goes wrong, like a wire coming loose inside a device and touching a metal enclosure. Without an EGC, that metal enclosure could stay energized and shock anyone who touches it.
How an EGC Protects You
Under normal conditions, no current flows through the EGC. It sits there doing nothing until a fault occurs. A ground fault happens when electricity escapes its intended path and flows through something it shouldn’t, like the metal housing of a power tool or the steel frame of a panel box.
When that happens, the EGC gives fault current a low-resistance route back to the electrical panel. This rush of current is what triggers a circuit breaker or fuse to trip, cutting power to the circuit. The key detail: the EGC has to carry enough current, fast enough, to actually trip that breaker. If the path back is too resistive or broken, the breaker may never trip, and the metal surface stays dangerously energized. That’s why the National Electrical Code requires EGCs to form what it calls an “effective ground-fault current path,” meaning one with low enough impedance to reliably activate overcurrent protection.
What an EGC Looks Like
If you’ve ever seen a bare copper wire bundled alongside the black (hot) and white (neutral) wires inside standard household wiring, that’s the EGC. In nonmetallic sheathed cable (the most common residential wiring, often called Romex), the EGC is typically a bare copper wire. But EGCs come in several forms depending on the installation.
When the EGC is an insulated wire, it must have a green outer finish, or green with one or more yellow stripes. Conductors sized 6 AWG and smaller are required to be green along their entire length. Larger conductors (4 AWG and up) can be identified at their termination points instead of being green throughout, which is a practical allowance since large-gauge green wire would be expensive and hard to stock.
In many commercial and industrial buildings, the EGC isn’t a separate wire at all. The metal conduit that encloses the circuit wiring often serves double duty as the equipment grounding conductor. Rigid metal conduit, intermediate metal conduit, and electrical metallic tubing all qualify. The metal pathway itself carries fault current back to the panel if a ground fault occurs.
Permitted Types of EGCs
The National Electrical Code recognizes a surprisingly wide range of materials and assemblies that can serve as an EGC:
- Copper, aluminum, or copper-clad aluminum wire, either solid or stranded, and either bare or insulated
- Rigid metal conduit and intermediate metal conduit
- Electrical metallic tubing (EMT)
- The armor of Type AC cable, the metal-clad wiring common in older apartments and commercial buildings
- Type MC cable that contains a grounding conductor or has a metallic sheath listed for grounding
- Surface metal raceways listed for grounding
Flexible metal conduit can also serve as an EGC, but only under tighter restrictions: the circuit must be protected at 20 amps or less, the conduit can’t exceed 1ΒΌ-inch trade size, and the total length of flexible conduit in the ground-fault return path can’t exceed 6 feet. These limits exist because flexible connections are inherently less reliable as current-carrying paths than rigid ones.
How EGCs Are Sized
The size of an EGC isn’t based on the load it serves day to day (since it normally carries zero current). Instead, it’s sized based on the rating of the circuit breaker or fuse protecting the circuit. A 15-amp or 20-amp household circuit typically requires a 14 AWG or 12 AWG copper EGC. Larger circuits need proportionally larger grounding conductors so they can carry enough fault current to trip the breaker quickly.
These minimums are spelled out in a table in the electrical code. The principle is straightforward: the bigger the breaker, the more fault current could potentially flow, so the grounding conductor needs to handle that current without overheating or creating too much resistance.
EGC vs. Other Grounding Components
People often confuse the EGC with two related but distinct parts of the grounding system. The grounding electrode conductor (GEC) is the wire that connects your electrical panel to a grounding electrode, usually a metal rod driven into the earth or a connection to a building’s metal water pipe. Its job is to stabilize voltage relative to the earth and dissipate static or lightning energy. The EGC, by contrast, lives inside the circuit itself and exists solely to clear faults by tripping breakers.
The neutral wire (grounded conductor) is another source of confusion. The neutral carries current during normal operation, completing the circuit back to the panel. The EGC carries current only during a fault. In the main panel, the neutral bus and the grounding bus are bonded together at a single point, but everywhere else in the system they remain separate. Mixing them up downstream of the panel creates dangerous conditions where metal enclosures could carry current during normal operation.
Bonding: Connecting Everything Together
For the EGC to work, every metal component along the circuit path needs a reliable electrical connection. This is called bonding. In conduit systems, bonding happens through listed set screws or compression-type couplings and connectors that join each section of conduit tightly to the next and to each enclosure. If a connection is loose or corroded, the ground-fault path is compromised.
Where standard connections aren’t reliable enough, an equipment bonding jumper fills the gap. This is a short conductor that bridges between the EGC and an enclosure, a neutral bar, or a grounding bar inside a panel. Communications systems, metal gas piping, and other non-current-carrying metal parts that could become energized also require bonding to the grounding system, often through a connection to the EGC.
The practical takeaway: an EGC is only as good as its weakest connection. A single loose fitting, a corroded joint, or a broken wire anywhere in the path can prevent a breaker from tripping during a fault, leaving metal surfaces energized and creating a shock or fire hazard.