What happens if a grounding wire is missing?

Without a grounding wire, fault current has no safe return path. Metal parts of equipment could become energized, creating a shock hazard and preventing the breaker from tripping promptly.

Is a grounding wire the same as a neutral wire?

No. The neutral carries return current during normal operation, while the grounding wire carries current only during a fault. They serve different safety functions and must not be interchanged at outlets.

What size grounding wire do I need for a 20-amp circuit?

A 20-amp circuit requires a minimum 12 AWG equipment grounding conductor per NEC Table 250.122. Using a larger size is acceptable but not required.

Can I use a ground wire with green insulation in place of bare copper?

Yes, green-insulated copper is an accepted equipment grounding conductor. Both bare and green-insulated conductors are recognized by the NEC for grounding purposes.

Do older homes have grounding wires?

Many homes built before the mid-1960s used two-wire cable without a grounding conductor. Upgrading these circuits with a grounding wire or adding GFCI protection is a common repair recommended during inspection.

Grounding Wire — Equipment Grounding Conductor Explained

A grounding wire is a conductor that provides a low-resistance path for fault current from electrical equipment back to the service panel and ultimately to earth.

Grounding Wire diagram — labeled parts and installation context

What It Is

A grounding wire, also called an equipment grounding conductor or EGC, ensures that metal parts of electrical devices, enclosures, and raceways remain at earth potential so that a ground fault triggers the overcurrent device rather than energizing surfaces a person could touch. It is a fundamental safety element in every modern electrical installation and is required by the NEC in virtually all branch circuits, feeder circuits, and service-entrance installations.

The grounding wire does not carry current during normal operation. It serves solely as a safety path that activates only when insulation fails and current flows to a metal enclosure or equipment frame. When this happens, the grounding wire carries the fault current back to the panel's ground bar and neutral-to-ground bond, completing the circuit so the breaker or fuse can detect the overcurrent and trip.

Types

Equipment grounding conductors may be bare copper, green-insulated copper, or green-insulated with a yellow stripe. Bare copper is standard inside NM cable assemblies such as Romex and is the most common grounding wire in residential wiring. Green-insulated conductors are used in conduit systems where the grounding wire must be distinguishable from other conductors, and the green-with-yellow-stripe marking is used for isolated ground circuits serving sensitive electronics.

The grounding electrode conductor, which runs from the panel's ground bar to the ground rod or other grounding electrode outside, is a separate type of grounding wire that serves a different function. It establishes the earth reference for the entire system rather than providing a fault-current return path for individual circuits. Sizes range from 14 AWG for 15-amp branch circuits up to 3/0 AWG or larger for commercial service-entrance applications, as specified in NEC Table 250.122 for equipment grounding and NEC Table 250.66 for electrode conductors.

Where It Is Used

Grounding wires run inside every cable assembly or conduit feeding outlets, switches, fixtures, and appliances. They connect at outlet boxes via pigtails and wire nuts, at device yokes through the green grounding screw, at appliance frames through grounding lugs, and at the ground bar in the panel where all branch-circuit grounding wires terminate.

A separate grounding electrode conductor runs from the panel ground bar to the ground rod, water pipe bond, or other grounding electrode outside the building. In metal conduit systems such as EMT or rigid metallic conduit, the conduit itself may serve as the equipment grounding conductor if all connections are properly made, but many electricians and jurisdictions require a separate green wire inside the conduit for added reliability.

How to Identify One

In NM cable, the grounding wire is the bare copper conductor bundled alongside the insulated current-carrying wires. In conduit systems, it is the green or green-with-yellow-stripe insulated wire. At receptacles, the grounding wire attaches to the green hex-head screw terminal on the device yoke. At the panel, all grounding wires terminate at the ground bar, which is visually distinct from the neutral bar by the color of the wires landing on it.

A missing grounding wire is identified during inspection when a two-wire cable without a ground conductor is found, which is common in homes built before the mid-1960s. A grounding wire that has been cut, disconnected, or left floating inside a box is also a deficiency that must be corrected.

Replacement

A grounding wire that is cut, corroded, nicked through the insulation, or entirely missing must be replaced or added to restore the safety ground path. The replacement conductor must be the correct size for the circuit per NEC Table 250.122, which requires a minimum of 14 AWG for 15-amp circuits, 12 AWG for 20-amp circuits, and 10 AWG for 30-amp circuits.

Pulling a new grounding wire through existing conduit is straightforward if there is sufficient fill capacity. Replacing the grounding wire inside NM cable typically requires replacing the entire cable run. In older two-wire homes without grounding conductors, adding GFCI protection at the first outlet in each circuit is an accepted alternative per NEC 406.4(D)(2) when rewiring is not practical. All grounding work should be performed by a licensed electrician.