In U.S. household wiring, the equipment grounding conductor is green or green/yellow, or bare copper; it is never white/gray (neutral) or a hot color.
Ground Wire Color In U.S. Home Circuits: What To Know
The ground path carries fault current back to the source so breakers trip fast. In homes, you will see a green insulated wire, a green wire with a yellow stripe, or bare copper. All three mark the equipment grounding conductor in branch circuits and feeders. Inside nonmetallic cable such as NM-B, the ground is usually bare copper. Inside flexible cords and device pigtails, the ground is often green or green with a yellow stripe. The color is reserved. Do not use it for any other purpose.
| Conductor | Allowed Or Typical Color | Code/Notes |
|---|---|---|
| Equipment grounding conductor | Green, green/yellow, or bare copper | Reserved colors for grounding; may be bare in cables |
| Grounded conductor (neutral) | White or gray; or three white/gray stripes | Reserved identification for neutrals only |
| Ungrounded conductor (hot) | Any color except green, white, or gray | Common in homes: black, red, blue |
Why Green Or Bare Counts As Ground
The equipment grounding conductor bonds metal boxes, device yokes, and appliance frames. If a fault touches metal, the low-impedance path sends current back to the panel. The breaker opens. Touch voltage drops fast. That is why the color must be clear and consistent from end to end. A green or green/yellow jacket tells you the wire’s only job is equipment grounding. Bare copper inside cable does the same job, without insulation. Both are acceptable when sized and installed under the Code.
Code Pointers In Plain Language
Color rules come from widely adopted standards. The section on equipment grounding conductor identification sets green or green/yellow, or bare, as the allowed choices for that role; see NEC 250.119. The section for neutrals, 200.6, lists white or gray insulation or three white or gray stripes on a non-green background. Device grounding terminals are marked green under 250.126, which is why the ground screw on outlets and switches is green. Local jurisdictions adopt the NEC on a cycle, so always follow the edition in force where you live.
What Ground Isn’t
Ground is never the white or gray wire. White and gray mark the grounded conductor, also called the neutral. The neutral carries load current in normal use. It is bonded to the service grounded conductor at the service equipment only. Downstream, it must remain isolated from equipment grounding conductors. Mixing them in a device box creates shock risks and nuisance trips.
Ground is also not a hot. Hot conductors feed power to loads. In homes they are usually black or red, and sometimes blue. Switch legs and travelers may use other colors. None of those can be green, green/yellow, white, or gray. Those reserved colors avoid confusion when you open a box years later. U.S. workplace rules also require clear identification of grounded and grounding conductors; see OSHA 1910.304.
How To Verify The Ground
Color tells a story, but testing proves it. Work with the breaker off while making up connections. Restore power only for tests, then turn it off again before touching conductors.
Three-Light Plug-In Tester
For a 120-volt receptacle, plug in a three-light tester. Two amber lamps mean correct polarity and a present ground. One amber lamp at the right position often signals an open ground. Follow the legend on your tester body. Note that testers can be fooled by certain wiring errors, so confirm with a meter if readings seem odd.
Multimeter Check
Set the meter to AC volts. Insert one probe into the small slot (hot) and touch the other to the round ground hole. You should read line voltage. Move the second probe to the large slot (neutral). The reading should be the same. Then measure between neutral and ground. The reading should be near zero under light load. A high reading hints at a loose bond or bootleg wiring.
Grounding Clues On Outlets And Switches
Device hardware gives quick hints. The green screw marks the grounding terminal. The silver screws connect to the neutral side. Brass screws connect to the hot side. A yoke with a threaded green hole accepts a ground screw when a pigtail is needed. If the box is metal and the device yoke is bonded to it with an approved means, the yoke can serve as the grounding path for the device face.
Bonding The Box
A bare or green pigtail from the device often bonds to the metal box under a green screw. Use a listed 10-32 machine screw or a listed clip. Do not use random drywall screws. If the box is plastic, run the equipment grounding conductor directly to the device’s green terminal.
Common Home Scenarios And How Ground Looks
Every home has a mix of cable types and box materials. Use the scene to read the grounding method before you touch anything.
| Scenario | What You Will See | Quick Check |
|---|---|---|
| Newer NM-B cable to a plastic box | Bare copper pigtail to device green screw | Tug the pigtail; it should be secure under a green screw |
| Newer NM-B cable to a metal box | Bare copper tied to a green screw on box and to device | Confirm box has a listed ground screw or clip |
| EMT or metal conduit system | No separate ground in the raceway; device bonds via yoke or pigtail | Check fittings are tight; meter from hot to box for line voltage |
| Old two-wire cable, no ground | Only black and white present; no bare or green | Use a GFCI device and “No Equipment Ground” label if allowed |
| Flexible cord on an appliance | Green or green/yellow conductor to frame | Confirm cord cap has the ground pin intact |
Old Houses And Two-Wire Circuits
Many older homes still have two-wire branch circuits with no equipment ground. You can replace a two-slot receptacle with a three-slot GFCI receptacle and apply the “No Equipment Ground” label when permitted. This does not create a ground; it adds shock protection. Where a grounding path exists through metal conduit or cable armor listed for grounding, you may bond the device to the box and use a grounding type receptacle.
Finding The Ground In A Switch Box
Switch loops add confusion. Older switches may have only hot conductors present. The ground may be a bare pigtail tied to the box or none at all. Modern codes call for a neutral in many switch boxes and a grounding means. When in doubt, pull the device gently and look for a bare copper or green conductor tucked in the back, or for a bonding strap that ties the yoke to the metal box.
Re-Identifying Large Conductors
When conductors are 4 AWG or larger, the Code lets you mark the insulation at the terminations instead of using a factory color the full length. For a large equipment grounding conductor, you can strip the covering, wrap green tape at the ends, or apply green labels that encircle the wire. For a large neutral, you can mark white or gray at the ends or use three white or gray stripes on a non-green background. These field markings help in big enclosures where factory colors are hard to see.
DIY Mistakes To Avoid
Bootleg grounds: Never tie the neutral to the ground screw on a receptacle to fake a ground. That can place full fault current on metal parts and shock anyone who touches them.
Wrong screw: Grounding to a metal box takes a listed 10-32 green screw or clip in the threaded hole or slot made for that purpose. Self-tapping drywall screws are not a substitute.
Unmarked re-purposed conductors: If a white wire must act as a hot in a cable assembly, re-identify it with tape or sleeve in a color other than green, white, or gray. Do not leave it plain white on a switch leg.
Quick Safety Notes
Shut off the right breaker and prove it with a non-contact tester and a meter. Use listed wirenuts or crimps for splices. Keep grounds continuous through every box. Cap every spare ground with a wirenut so it cannot touch a hot terminal. If anything looks scorched, corroded, or loose, stop and have a licensed electrician make it right.
Fast Recap
In U.S. homes, the ground wire is green, green with a yellow stripe, or bare copper. White or gray marks the neutral. Black and red are the most common hot colors, but many other colors appear. None of the reserved colors can be used for a hot. The green screw is the ground terminal on devices, silver is neutral, and brass is hot. Test when you finish. A clear ground keeps faults from turning into shocks.
Why Color Rules Matter For Safety And Troubleshooting
Clear color cues speed up work fast. When you open a box and spot a green or bare conductor, you know it belongs on device’s green terminal or a bonding screw on the box.
When you see white or gray, you know it belongs on neutral side. If a white was repurposed as a hot and not marked, a tech may grab it and get shocked.
Colors help with fault finding. A tripped breaker with a nicked bare ground touching a sharp box edge is easy to spot once you know a bare wire should never be on a current-carrying terminal.
Color keeps home projects consistent across rooms and years. The next person opening the box can follow the same cues you used and make a safe repair without guesswork.