I'll be replacing my ungrounded three-prong outlets with tamper-proof GFCI outlets in my home in the USA. Maybe I'm overthinking this, but is there a way to 'universally' mark the outlets as ungrounded for the sake of any future electrician?

I figure that if I mark on the inside of the outlet box or outlet the electrician will already be able to see the absence of a green wire. But I don't care to write UNGROUNDED on the outside of every socket with a permanent marker.

  • 1
    Code requires the outlet to be marked on the outside so someone plugging a device in can see there is no equipment ground.
    – Ed Beal
    Oct 30, 2018 at 13:37
  • 6
    @SolomonSlow no, it doesn't, it only prevents 3-prong plugs from being plugged in! If you want 2-prong receptacles, just buy them, they are sold at better electrical supplies nationwide. Not Dollar General. Whereas, the whole point of GFCI protection on ungrounded outlets is to allow 3-prong devices to be safely used with them. Oct 31, 2018 at 2:03
  • Oops! I somehow failed to notice the "GFCI" in this question. I withdraw my previous comment. "Ungrounded GFCI" transcends my understanding. Oct 31, 2018 at 12:47

3 Answers 3


The gfci outlet likely comes with a few stickers with "no equipment ground" on them.

That is the universal marker. Put them on visibly on the outlet itself and any that is protected by that gfci.


Markings where the socket user can see them are mandatory. If you don't like the ugly blue stickers that come with GFCIs, get smooth white cover plates and a thermal labelmaker.

Use the labelmaker to make GFCI protected and No Equipment Ground labels on white background material. They will look professional and like they're part of the cover plate.

The GFCI Protected stickers are needed when a GFCI device is used to protect additional plain outlets downstream in the circuit. Did you know you could do that?

While you're labeling, add a label for the location of the GFCI device, so people can easily find the RESET button.

If it's coming as news to you that GFCI devices can protect downline parts of a circuit, and that you only need one GFCI per circuit, then real simple: Do not use the LOAD terminals. They are not "extra terminals for the other 2 wires" -- they are special, and for wizards only. Just like the warning tape says. If you have 2 wires to attach to the 1 line "hot" screw etc., then use pigtails.

Using the LOAD terminals without really knowing how GFCI works, will endanger the success of your project by introducing lots of hard-to-understand complications.

The worst thing you can do is daisy chain GFCIs so each one's LOAD feeds the next one's LINE... That will make the network very annoying and confusing to use. It's also a "Yo Dawg" joke.


Code requires the outlet to be marked on the outside so someone plugging a device in can see there is no equipment ground. Every GFCI outlet I have purchased usually has a bunch of stickers in the box, but the marking is required to be visible on the outside after installing per NEC 406.4.2.

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