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My home has a couple of lamp posts in the front garden. One of the posts has a 1-gang metal outdoor box mounted to it, with a regular non-GFCI receptacle which I intend to replace with a GFCI so I can power Christmas lights with it (and landscape lighting during the rest of the year).

However on closer inspection of the box, I noticed that it is just screwed in to the body of the post. A Romex cable runs from a knockout in the back of the box through a hole in the post, but there's no sealing whatsoever in that knockout. Obviously this is a handyman job that's not up to code. It could have fooled me though because at first glance it looked like a good, sound installation (except the absence of a GFCI which should have raised a red flag, to be honest).

My first thought was to replace the box and install a new one the proper way, but my question is-- can an electrical box be properly mounted to a lamp post and still be in code? Any suggestions? Thank you.

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    What color is the sheath on that "Romex" ?
    – Ecnerwal
    Dec 1 '20 at 3:51
  • 14/2 from the box to the fixture, but the cable running out of the box down through the conduit back to the panel is 12/2.
    – Roabe
    Dec 1 '20 at 3:56
  • Sheath is yellow.
    – Roabe
    Dec 1 '20 at 4:01
  • Always a good bet to keep your electronic devices indoors not outdoors. See ecnerwal's answer for how GFCI protection happens without a "GFCI+receptacle combo device" right there. However protected outlets are supposed to have a "GFCI Protected" sticker. Dec 1 '20 at 18:10
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Misconception: You need a GFCI out in the weather to run your Christmas lights (or whatever.)

More nuanced view from experience: You need GFCI protection for that outlet. You may already have GFCI protection for that outlet that you don't know about. If you spend $3-5 on a plug-in outlet tester with GFCI test button, you can find out if you have GFCI protection on that outlet by plugging it in and pushing the button. If the power turns off, then you get to go looking for where the GFCI protecting it is. They live a lot longer if they are inside the house, out of the weather, with the outside circuit attached to their "Load" terminals.

Misconception: outside outlet boxes must be sealed! Reality: preventing bulk water ingress is good, but all outside conduits are defined as wet locations, and "perfectly sealing" outside boxes tends to mean that condensation does not drain out, rather than that they are dry.

If there's no cable clamp (which might well be sticking out into the lamp-post and require looking carefully from inside the box to notice) and the back of the box is not connected to conduit, that's an issue, but "sealing" is not really an issue, in general. You can stuff conduit openings with "duct seal" to reduce air and water movement, as well as (small) wildlife. That can reduce condensation.

As for mounting a box to a lamp-post, attach it with a couple of screws, drill a hole for the wire access, and either run conduit up to that hole inside the lamppost to run wires in, or use a cable clamp in the back of the box and run cable inside the lamp-post to a junction box with another cable clamp where you transition to wires in conduit, if you have conduit. Many lampposts just have direct buried cables run to them - if they are buried at a sufficient depth and are rated for wet locations and direct burial that meets code, though experience says that running wires in conduit has far less problems in the long run. Edit: actually, the lamp-post itself may qualify as a "conduit" of sorts, so you may not need a conduit inside it to run wires.

However, you have a more extensive problem here - if the cable sheath isn't gray, your cable really is "Romex" or NM/B, and it's not suitable for wet locations - which all exterior conduits are defined to be. The "Romex-like" cable that is suitable for wet locations is UF, and has a gray sheath. So all that cable needs to be replaced back to a point that is inside and dry (if you actually have conduit, you can replace it with THWN wires, rather than cables. Wires are a LOT easier to pull in conduit.)

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    Also, perfectly sealing an outdoor box puts a lot of stress on the seals themselves due to changes in barometric pressure -- having vent/drain holes instead means that the pressure inside the box balances with the pressure outside the box, taking away forces that drive water across the seal Dec 1 '20 at 4:19
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    Thank you for these clarifications. I actually have tried a GFCI tester based on a friend's suggestion that a GFCI somewhere "upstream" could be protecting the post and outlet, but I was unable to find any. The improper cabling is definitely a worry though. Luckily these posts are the only fixtures on the circuit, so I can just leave the circuit breaker off until I get this issue rectified.
    – Roabe
    Dec 1 '20 at 4:23
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    When you fix it, put a GFCI on the circuit inside the house. That can be a "deadfront" GFCI (without receptacles, just the test and reset buttons) or replacing the breaker with a GFCI breaker (but those usually cost more.) It can also be a normal GFCI, just label it to be clear that it's the "garden lamp circuit" and be aware of any additional things plugged into it that might overload the circuit.
    – Ecnerwal
    Dec 1 '20 at 4:26
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    before you dig everything up, look for an access panel on the pedestal of the lamp post. There is the possibility that an appropriate conduit run leads to it (or proper UF NM sheathed cable) and that the romex fed box/receptacle was an add-on that was tied together inside the post. Dec 1 '20 at 6:29
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    If you find proper wiring to the lamp post (as @JimmyFix-it suggested may be the case) but the improper NM-B within it, then it's dead simple to replace the improper NM-B with THHN/THWN for a safe/legal installation. Your local big-box store will have 25' spools of THHN for very reasonable prices, and it's much easier to work with (and cheaper) than UF is.
    – FreeMan
    Dec 1 '20 at 14:03

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