21

My house in California was built in 1989 (I believe) And in the last 5 years I've replaced at least 20 outlets myself (successfully), and noticed there were never any ground wires to connect to the new outlet (Decora style). The old outlet are exactly the same as the new outlets, the majority of the time.

I've read plenty of tutorials that point out that this is possible with older style homes and you simply just screw in the green screw firmly into the receptacle and wire everything back up like it was before.

Edit: I forgot to mention that all the outlets are housed in a metal box. But I don't know if the ground wire is connected to metal box because I physically can't see if it is.

  1. I guess my question is why don't I have any ground wires?

  2. Is this a bad thing? How does not having ground wires affect me as opposed to a newly built home that does have ground wires?

  3. Is my house actually grounded, just without the ground wire? For example I know that if you have a string of outlets and they all connect to a GFCI, then they are considered grounded. Correct?

The reason I bring this up, is because i'm gearing up to do some electrical work and this keeps nagging at me that I should address this issue before moving forward.

Some Hi-Res Images of my breaker and outlet HERE.

enter image description here

  • 5
    Are all the wires in the house run in metal conduit and metal junction boxes? – JPhi1618 May 28 at 20:40
  • 4
    If the house was built in 1989, it's very unlikely there is no grounding unless you're working in a addition or remodel that wasn't done properly. – JPhi1618 May 28 at 20:44
  • May be related, but you would also need self-grounding outlets and switches if this pertains to you. – JPhi1618 May 28 at 20:53
  • @Harper I can't. Unless I break walls to look behind it. – Sickest May 28 at 20:57
  • 2
    No, I mean the back of the boxes as in what's directly behind the receptacle or switch, which you say you've been changing right along. 1) remove the cover plate 2) remove the receptacle or switch. 3) note how wires enter and snap photo of it 4) edit post and hit mountain and sun button above edit window. – Harper May 28 at 21:05
25

Your house is wired using the EMT conduit wiring method. Individual wires are carried inside metal conduit. The conduit is the ground path. Most commercial and industrial buildings look exactly like this.

Since they are individual wires, they are able to use any of 11 wire colors to disambiguate circuits, instead of the usual black white red. If you wish to add wires, you'd buy THWN-2 wires, stranded is more flexible but more tricky to put on screws.


Switches do not need any further attention to grounding.

Lamps and receptacles may need further attention. Look closely at how the yoke (metal frame, notably the top and bottom ears) make contact with the steel box. If all this is true:

  • There is hard face-contact between the yoke and the metal box directly; the yoke is not floating out proud of the metal box connected only by screw threads, and
  • The yoke and metal box are not contaminated by paint, rust or other detritus, and
  • There is not any little little paper/plastic square that would capture the yoke screws,

then this clean hard-flush contact is an acceptable ground path.

If any of this is insufficient, you must ground the receptacle to the box. Somewhere in the back of the box will be a hole slightly different than the others. It is tapped #10-32 for a ground machine screw (bolt). You can use any 10-32 bolt (machine screw). They sell cute green 10-32 bolts in the hardware store, with or without pigtails pre-attached. Those are perfect.


Metal conduit is an excellent wiring method, and I use it whenever I can. You can use existing conduit routes to add circuits (up to 4 per conduit), so it makes it easy to customize your wiring. For instance if you keep tripping breakers in the kitchen, just throw another circuit in alongside the existing one. Even if you're extending, you can use existing conduit for the homerun - there's no need to bust up any more drywall than you absolutely have to.

AFCIs were originally invented for problem appliances (one in particular: electric blankets). But they were found to protect all sorts of "NM cable, plastic box, lazy installation" type problems coughbackstabscough, so AFCIs are now required on almost every circuit. EMT doesn't have those problems, so I don't install AFCI on circuits in metal conduit. (except bedrooms, obviously).

  • BTW: he can also use self-grounding receptacles to take care of the receptacle-to-box grounding duty (and may be required to, for flushmount boxes) – ThreePhaseEel May 28 at 23:59
  • 1
    @Sickest -- just googling "self-grounding receptacle" found me a link to the product page for the Legrand/P&S 3232TRSW, I know offhand Leviton also makes some... – ThreePhaseEel May 29 at 11:40
  • 2
    Wait, so in EMT, I'm not supposed to use those little green plastic outlet extenders, and I'm supposed to be removing the cardboard screw retainers? – Mazura May 29 at 16:24
  • 1
    @Mazura Either that, or self-grounding outlets, or pigtail the ground wire off the box screw... the latter will be mandatory if the drywall ears are holding it proud of the metal box. Yeah I know, I've fit dozens of receptacles with those little squares, and now have to go back and fix them. But you're often trimming those screws anyway; as shipped they are long (for proud-of-drywall use), and you must nip them or they'll bottom out on the conduit pipe. – Harper May 29 at 16:44
  • 1
    @mickeyf that screw thread contact is precisely what is allowed for switches and not allowed for receptacles. I am not saying the retainer insulates; I am saying it conducts not enough. – Harper May 30 at 14:03
8

Your pictures appear to show metallic conduit carrying the wires to your boxes. The conduit is also an NEC approved grounding path, so no separate grounding wire is required for the distribution. This evidently is not the case in some other countries.

Current best practice (and code, so far as I recall) is to attach a grounding pigtail from the box (there is normally a raised bump with a threaded hole for this exact purpose) to the device, rather than depending on the mounting screws as a grounding means.

  • In your opinion is metal conduit in a home a normal thing? Is it overkill? or is it what they did back then because 12-2 gauge cable didn't come with a grounding wire? I've recently helped an uncle build his new home and they did not put any metal conduit to carry the wires. – Sickest May 28 at 22:09
  • 5
    It's not "normal" but it's an excellent idea - it's a much more damage-resistant wiring method, as any number of chewed-bare NM cables I've seen when remodeling will attest, so your house is a LOT less likely to "have an electrical fire" it also makes upgrading or changing much easier. NM is just "cheap" in every sense of the word, which is why it's common. NM is ONLY allowed in residential, as the fire risk is considered too great for other occupancies... – Ecnerwal May 28 at 22:12
  • 2
    So basically I need to go through every single outlet in the house, and attach a ground wire to the outlet and the metal box to have the safest possible scenario? – Sickest May 28 at 22:15
  • 2
    @Sickest -- it's certainly much more common to see metal conduit in commercial/industrial/institutional work, but it's definitely not forbidden in residential, and some places (hi, Chicago!) require metal conduit in all construction, even – ThreePhaseEel May 28 at 23:55
  • 5
    Conduit is definitely a "class act" way to do it. The beauty thing of conduit is you can use existing conduit routes to add circuits (up to 4 per conduit), so it makes it easy to customize your wiring. For instance if you keep tripping breakers in the kitchen, just throw another circuit in alongside the existing one. Even if you're extending, you can use existing conduit for the homerun - there's no need to bust up any more drywall than you absolutely have to. Also you get the wire colors you want, which is much easier on troubleshooting... – Harper May 29 at 0:06
4

If your house was built in 1989, it would have needed to have ground wires in all of the outlets. The requirement went into effect in the 1968 NEC. Now if your house was built in 1969 (20 years earlier), it might be that in your state, the 1968 NEC was not yet adopted. Some states take a while to adopt changed to the NEC. But not 20 years...

Grounding is a safety issue, but because it is a MANDATORY safety issue, many electronic devices rely upon that solid ground connection to eliminate electrical noise (or give it an easy path to ground). If you have 3 prong outlets but the ground wire is not connected, you have no grounding so not only is it less safe, it is also likely unhealthy for some of your electronics. In a nutshell if your device has a 3 prong plug, it probably NEEDS the ground connection, if it has a 2 prong plug, it doesn't.

A GFCI by the way does NOT "fix" that issue, it just looks at the current flow coming in and going back, and if they are not the same (ostensibly because something is going to ground) it opens the circuit.

  • Let's assume I do have grounding. If i can't see the grounding cable physically, how would the electricians have grounded my outlets? What would have been the standard way of doing that to code? you also discuss how it's unhealthy for some of my electronics, can you go into more detail about that? I also want to note, we have zero 2 prong plugs. – Sickest May 28 at 21:29
  • If you have METAL outlet boxes, it was acceptable at one time to attach a ground wire to the box, then when you attached the receptacle to the box, it was grounded. That is no longer allowed though, you must attach the ground wire to the device and have a "pigtail" that attaches to the box. If your boxes are not metal, it is illegal altogether to not have the ground wire attached to the device. – J. Raefield May 28 at 21:34
  • Some electronic devices create what is called "common mode noise" that is electrical noise / hash that is trying to get back to ground. If you don't give it an easy path to ground, it floats around (for lack of a better term) in the power circuit making trouble for your sensitive electronics as it tries to find a way to get to ground. that can eventually cause components in your devices to fail prematurely. – J. Raefield May 28 at 21:37
  • "That is no longer allowed though, you must attach the ground wire to the device and have a "pigtail" that attaches to the box." Would it possible to simply cut a grounding wire and attach the wire from my outlet to the metal box and then it would be up to code? Because i'm assuming it's no longer allowed because it's possible the outlet isn't touching the metal box, correct? – Sickest May 28 at 22:03
  • 3
    The pictures were not up when I responded. Yes, conduit, though not terribly common in residences, changes the game a lot. – J. Raefield May 29 at 0:35

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

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