I'm in a similar as situation described here: Can a mud ring be used in reverse?

I have an octagon box outside behind stucco. I want to plug in string patio lights. The lights have a 3 prong plug. So I'd need to use a lamp-to-outlet adapter adapter

Then a cheater cheater

This seems bad.

There's no ground conductor outside in the octogon.

I thought I'd replace the switch with a GFCI switch for a little extra protection.

The GFCI manual says "The load must be grounded". Is this true? I found this switch wiring here: https://www.electricaltechnology.org/2020/04/wire-gfci-combo-switch-outlet.html#wiring-a-gfci-combo-switch-outlet-with-a-light-bulb

which seems to say I can do what I think I want, but it's a cartoon.

Is this possible and if so, is it worth doing?

  • 2
    That's not a GFCI switch. That is a combo switch-outlet. You can get just a GFCI switch, it looks like a deadfront (only buttons, no sockets). Test/Reset are Off/On. It is rated for that service. Nov 30, 2021 at 0:46
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    Regardless, what you are trying to do is a Code violation, as you are provisioning a new receptacle, and that always requires grounding (and GFCI if outdoors). That said, I think your idea is more than safe enough. Nov 30, 2021 at 0:53
  • thanks! @Harper-ReinstateMonica I didn't see the switch-only version at the local home store. I see them online now. If I use one of those... I'm not provisioning a new receptacle maybe?
    – tladuke
    Nov 30, 2021 at 1:15
  • 1
    Can you take the cover off your octagon box and measure its width please? Nov 30, 2021 at 2:43
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    It's very behind stucco. The mounting holes/bolts are 2" 3/4 apart. And yes, the "cover" is currently just the cheap round indoor lamp holder mounted sideways too it... I'd rather attach an outdoor box if there was a way to do that without dealing with the stucco.
    – tladuke
    Nov 30, 2021 at 17:41

1 Answer 1


Change the lamp to a receptacle.

Since you are not using the lamp at all, simply tear it off the wall and store it until you no longer want a receptacle there. Now you're looking at an octagon box that is grounded.

Since it's the smaller and largely obsolete 3-1/2" box, you'll need to mount an extension box that steps up to either the more common 4" octagon box, or a 4x4" square box. An electrical supply house will have the shop knowledge to know exactly what you want; box stores tend to be a disaster for "less popular" stuff like this.

Once you have a box capable of accepting a receptacle, then install one, along with an outdoor in-use cover, such as a Taymac MM410CA for 4" octagon boxes.

"That was easy"

Since it is an outdoor receptacle, it needs GFCI protection. NOW, apply your idea to use either a GFCI switch (deadfront with switch rating), or the GFCI switch/receptacle combo device you proposed, as you prefer.

  • 1
    I tried a Taymac MM410CA first. It doesn't fit. If there's some kind of adapter I can use without breaking away the stucco, I'd like to know what it is.
    – tladuke
    Dec 1, 2021 at 2:24
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    @tladuke I see the problem. You have the smaller (and obsolescent) 3-1/2" octagon box. You'll need an adapter box to get you to the modern/standard 4" octagon box, or just to a 4" square box if you can find that. Edited. Dec 1, 2021 at 3:20
  • Thank you. Google is also useless for this it seems. I don't think the box itself is grounded though.
    – tladuke
    Dec 1, 2021 at 17:56
  • @tladuke well, ground can always be retrofit, one way or the other. They liberalized the rules for doing that in 2014. Dec 1, 2021 at 19:44

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