Are there any special requirements I should be aware of before adding lights and outlets to my covered back patio? I know GFCI protection will be required on the outlets, but can I run regular Romex cable over soffit? It's an open air, concrete patio and wood post construction with typical soffit ceiling.

There is an empty outlet box installed on the far right of the porch, about 15-18 inches off the ground. I would like to use that, and add a second outlet closer to the french doors via conduit and THHN.

I don't have a picture of the porch itself, but it can be seen behind the playground. The ceiling material is the vinyl soffit, which I thought to be typical for porches and patios.


  • 1
    You'll want to either A) Use a GFCI breaker, or B) Use a GFCI outlet inside and put all the patio devices on the LOAD side of the outlet. While outdoor GFCI outlets are made, even when installed in water-tight boxes, the elements are pretty harsh on them and they require more frequent replacing, and they're a bit spendy to have to replace them more often rather than less often.
    – FreeMan
    Commented Jun 25, 2020 at 12:56
  • I'm not too familiar with patio roofs that have a soffit ceiling, so I'm not sure this qualifies as "typical". Can you post an overall shot of the patio/roof, then a couple of detail shots of the soffit where you're planning on running the wiring. Also, indicate where you're planning on putting the outlets. They're probably not going up in the soffit, so there will be extra considerations for them.
    – FreeMan
    Commented Jun 25, 2020 at 13:21
  • I do not think this is a duplicate the op said there was a porch and the construction had soffit type construction the answer you linked was not the same. If the porch had a plastic roof it would not be allowed! So much different.
    – Ed Beal
    Commented Jun 25, 2020 at 13:50
  • Not at all what I was envisioning - the pic makes things so much more clear, thank you! (Nice playground, BTW!)
    – FreeMan
    Commented Jun 25, 2020 at 14:03
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    @FreeMan and Ed Beal thank you both. We just put it up for the kids this past weekend. About 25 work hours with my dad and grandfather's help. Glad it's finished lol
    – clwhoops44
    Commented Jun 25, 2020 at 14:43

1 Answer 1


Code considers areas normally dry to be ok for nm cable 334.10. Under your roof is one of those locations that is not subject to dampness or wetness. Some jurisdictions consider a porch to be a damp location. It usually depends on the roof type. For example, a normal 3 tab roof with tarpaper is considered a dry location, but a roof with corrugated plastic and even metal if not insulated is a damp location.

If you use a GFCI in this location, it needs to be WR weather rated, as the electronics are coated to protect them from moisture. They cannot be located above 5'7", but they can be used to protect the load side.

I would think as long as above 8', exposed romex or NM cable would be allowed by your description of the soffits & normal roofing.

Updating because of change to thhn;

Where damp or wet, THHN /THWN cable (almost all thhn is dual rated but thwn is the wet rating) needs to be used. Your circuit will need to be in conduit box to box. 1/2" will be fine for your setup. All wiring methods below 8' require protection, but THHN requires conduit from start to finish.

The reason most home owners use UF and NM wiring methods is because 12&14 gauge circuits with thhn requires 3 different colors: hot usually black, neutral usually white, and ground usually green. (Hot can be any color other than gray, white, green. Neutral can be white or gray, ground can be green or bare).

Home owners usually use pvc conduit as it is easy to cut and glue. From your box, there can not be more than 360 degrees in bends or 4 90's. Wire pulls get tough after 3. If you need more than 360, a conduit body is normally installed. I use a conduit body at a 90 in many cases, called an LB, LR, or LL (the hole being back, right, or left). There are also form C bodies that are inline. A box can also be used.

The one thing I see home owners do wrong in most cases is the wrong kind of box. Outside, a bell box or weatherproof box is required unless recessed in the building structure.

The pvc conduit needs a strap within 3' from the box and supports per table 352.30 1/2"-1" max space 3'.

These are the additional things to think about, but they should get you on your way to a safe install of your lights and receptacles.

  • Aren't standard GFCI's WR??? +
    – JACK
    Commented Jun 25, 2020 at 13:57
  • I'm pretty sure I've seen some GFCIs specifically labeled "WR" and they were priced higher than others, @JACK, so... probably not.
    – FreeMan
    Commented Jun 25, 2020 at 14:05
  • No freeman is correct WR rated gfci’s are special for outside use but I also use them in bathrooms where humidity is higher they last longer because the electronics are coated / potted to prevent moisture problems.
    – Ed Beal
    Commented Jun 25, 2020 at 14:16
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    I wasn't aware of that but then I always installed the GFCI's inside and daisy chained the outside outlets to it.
    – JACK
    Commented Jun 25, 2020 at 14:24

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