11

I was replacing one of the outlets in the kitchen in my home and I noticed the ground wire goes to a screw on the back plate of the outlet box, and a green ground wire runs from the same screw on the back of outlet box, to the receptacle. I opened a few more outlets in the house and noticed that they are all wired that way.

I'm no expert, so I was curious if these outlets are considered grounded properly or not. Or if I should go into every outlet in the house and run the ground wire directly to the receptacle and ditch the green wire to the outlet box.

Thank you

Outlet

7
  • 2
    You probably want to get a test plug. It is 3 prong, tester that plugs into any receptacle and LED lights show if , and what the problem is. Commented Aug 25, 2023 at 19:39
  • Do any of these existing questions answer yours?
    – isherwood
    Commented Aug 25, 2023 at 19:40
  • Does a crimp-on eyelet count as a wire? One screw; one wire. I'd leave the eyelet under the screw, pig tail it into the nut, then use that removed bare copper to ground the device. And you need to pig tail the yellows. And prob the neutrals; if they did it on one side, then.... Which prob are actually are the neutrals... (other wires are black) gah
    – Mazura
    Commented Aug 25, 2023 at 20:58
  • 1
    A tester isn't going to tell you if it meets code, which it doesn't now that you've touched it. - What planet are you on with yellow as a neutral color? Which is the hot wire, neutral wire and ground wire?
    – Mazura
    Commented Aug 25, 2023 at 21:07
  • 9
    If you note, @Mazura, that "yellow" insulated wire goes into a silver braided jacket cable housing. That's old stuff here in the US. That means that the wires in it are old, too. That's white insulation that's yellowed with 50+ years of aging. Also, since when does opening an outlet box automatically mean that it must be replaced to modern code standards? Heck, AIUI, the OP could replace the receptacle with a self-grounding unit with GFCI and the rest of the wiring is still grandfathered. If you've got a code reference that says otherwise, please share it!
    – FreeMan
    Commented Aug 25, 2023 at 22:01

3 Answers 3

11

They are grounded.

One reason the person who used the insulated ground wire instead of bare wire may have done so, is that the bare wire can sometimes make a short with the hot wires if not placed correctly in the box.

You will need to test if the bare ground wires are correctly connected back to the panel to be sure of proper grounding. One simple test is to use a multimeter to see if you get 120V (or your local expected voltage) between the hot and ground wire or the box.

3
  • I agree they appear to be grounded, but this answer says nothing about why. From the picture, it appears there is a bare copper ground wire running with the live/neutral wires, which the outlet's ground wire attaches to via a screw at the back of the box. I would guess the idea is to ensure that the box itself is also grounded.
    – Matthew
    Commented Aug 28, 2023 at 15:50
  • @Matthew That is why I mention the test to make the ground wires were connected properly.
    – crip659
    Commented Aug 28, 2023 at 16:05
  • 1
    ...but if someone didn't notice that those wires are connected (as I didn't, the first time I looked), your last paragraph appears to be a non sequitur. Nor do you say anything about why the box might be wired this way. Consider my first comment as a suggested addition...
    – Matthew
    Commented Aug 28, 2023 at 16:24
15

Let me guess, you're seeing diagrams for plastic boxes?

Routing all cable ground wires to the metal box is mandatory. Switches and some receptacles will automagically pick up ground via their mounting screws; an additional ground strap is wholly unnecessary.

"Some receptacles" describe a case where the receptacle yoke has hard clean metal-metal contact with the box flange, or where the receptacle has a wiper on the screw hole to help pick up ground. These latter receptacles are marked "Self-grounding".

3
  • 8
    To be fair, I'm accustomed to nothing. Just cracked this open and it didn't look like the diagrams online so I figured I'd be safer to ask a question to ensure the green wire wasn't making it unsafe in some way. I appreciate you explaining it to me, as you only learn by asking questions :)
    – z0nktastic
    Commented Aug 25, 2023 at 19:47
  • 6
    @z0nktastic you did the right thing by asking. Sometimes the tone of answers on SE is a bit weird, but consider that the answers are addressing both your question and the next hundred people who get sent this way by search engines, so often the answer is a bit more "generalised" Welcome to the site and do also have a go at answering any questions that you have new knowledge to share.
    – Criggie
    Commented Aug 26, 2023 at 11:44
  • @z0nktastic Ah, then, the people who made the diagram you were looking at, were accustomed to plastic boxes. Commented Aug 26, 2023 at 14:40
3

Based on your photo, the outlet (receptacle) looks properly grounded for when the home was constructed, assuming it's in the U.S. Based on the jacket appearance, the yellowed white wires, and most importantly, the apparently smaller bare grounding wires, I would guess this was done in the 1960's. I have a similar house.

As one commenter said, buy a three-lamp tester plug (hardware or home improvment store) and test all your outlets. If you want to nerd-out on this, an analyser such as an Extech CT80 will tell you the ground impedance and the voltage drop under load conveniently.

In today's electrical code, a new kitchen outlet requires a GFCI. Your outlet shows two cables connected to it, so there is likely another outlet fed by it. If you find the first outlet in the circuit, this could be replaced by a GFCI receptacle to increase safety, and would protect all outlets on the circuit.

(Allways turn off the circuit breaker before working on wiring.)

Smaller grounding wire: https://forums.mikeholt.com/threads/old-romex-smaller-ground-conductor.132171/

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.