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Community and Q&A

Installing Outdoor Electrical Outlets

jeffsgta | Posted in Mechanicals on

I want to add a couple of outlets outside to plug in uplighting and Christmas lights. I need to drill though brick to get the 14/2 outside. Should I run conduit through the wall from inside to outside to get power outside? It seems like the right thing to do but it requires a large hole in the wall. I see a lot of people just run the 14/2 through the wall and caulk it. That seems kind of strange to me, I just want to do it right.

Also, should I run 12/2 or 14/2? Should I use a 20 amp or a 15 amp breaker? Should I use 15 or 20 amp receptacles? I know I need a GFCI too. Should I use outdoor or indoor wire?

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  1. Expert Member
    Akos | | #1

    If you are in the great white north, I would get a copy of PS Night's Electrical Code Simplified. Well worth to have it if you are doing any wiring for your own house.

    As for the outdoor connection, you can run standard 14-2 romex to the device box. No need for conduit or outdoor wire as long none of the wiring is run inside the brick and not exposed to the outdoors. You do need a wire retainer at the back of the box. What I've done is drill a 1/2" hole for the wire and enlarge it a bit on the outside with a 1" bit to make room for the wire clamp.

    Pull the wire into the outdoor box, clamp the wire than mount the box to the wall. You'll need to seal around the wire with putty inside the box. A squirt of spray foam into the hole in the brick before you set the box also doesn't hurt.

    1. jeffsgta | | #2

      I am in Indiana. Not exactly the great white north. Is that code book still good to get?

      Thanks for the info. So 14/2 and a 15 breaker? What kind of putty would I use? Does it have to be fire break spray foam?

      1. Expert Member
        Akos | | #9

        Canadian electrical code is tends to be fairly close to US. There might be a similar US version of simplified electrical code though which would be better in your case.

  2. christopherw | | #3

    If you're doing all the work to run a new line, I would run 12/2 20 AMP myself. Works for anything 15 amp does, but you can optionally plug in something that needs 20 amps if you ever run into the need.

  3. Expert Member
    BILL WICHERS | | #4

    You can run the NM cable through the wall and seal it, but my preference is to run a short stub of conduit (called a "sleeve" in the trades) through the wall. I use an NM-to-EMT clamp on the end of the conduit where it pokes through wall inside (assuming you're in basement rim joist area here). You then just seal around the conduit. I like to stuff a short piece of backer rod into the conduit as a sort of removeable air and bug seal.

    I only use 12/2 these days for receptacles. I'd especially wire that way for any outdoor receptacles that are likely to run tools. The heavier gauge wire has less volt drop for a given load, which is a good thing. I would use either a 15 or 20 amp breaker (20 amp requires the use of 12 gauge wire), and I'd use a GFCI breaker to protect an exterior plug. I don't like using the combo GFCI/receptacle devices outdoors since they never seem to last.

    BTW, use a "weather resistant" receptacle in your outdoor box. They are a little more expensive, but they're made to hold up better in outdoor applications.

    The usual sealing "putty" use for sealing around cable penetrations is known as "duct seal" in the trades, and is a sticky clay-like material. It's cheap, and is usually sold in 1 and 5 pound bricks.


    1. jeffsgta | | #6

      Ok. I do like the sleeve idea. What size sleeve would you use? With the adapter in the back of the box it it looks like a 1.25 inch hole. What would you use to seal around the sleeve? Spray foam? Caulking? Do I need to any kind of fire break spray foam?


      1. Expert Member
        NICK KEENAN | | #7

        Presumably you're using an outdoor box? If it's metal it will have threaded holes, if it's plastic the holes can be either threaded or smooth. Smooth is meant to be glued to PVC conduit. Threaded is meant for a threaded fitting. I would go with 1/2" PVC conduit. If your box is threaded a threaded adapter like this is what you want:

        Generally the box will have either 1/2" or 3/4" holes. If you have 3/4" holes a bushing gets it down to 1/2":

        Note that electrical fittings are sized in what is called "trade size" which has no relationship to inches as they are used in the rest of the English-speaking world. So 1/2" trade size fittings are nowhere near 1/2", they're quite a bit bigger. Don't try to measure the holes, go by what the label says and if that fails pull things out of the parts bin and make sure they fit. A 1/2" PVC conduit has an outside diameter of just under 7/8" and needs a hole drilled with a 1" bit to fit easily.

        With a glue-style box the conduit goes in with no adapters and the hole can be the same diameter all the way through.

        I like to shoot silicone into the hole before putting the conduit in. I also draw a horseshow shaped bead of silicone on the back of the box on the top and sides. Once the box is in place I seal it from the inside too.

      2. Expert Member
        BILL WICHERS | | #8

        I would use 1/2" EMT. You'll need about a 1" hole to clear the fittings though, maybe even a bit bigger. I would use a metal exterior box.

        You can use canned foam to seal around the sleeve. That's what I always do. If you use the fire rated canned foam you're safe regardless, and that's all I ever use since that's all that they make for the pro gun. I don't think you really need firestop here though, since you're not putting a pathway in between fire spaces. Fire stops are usually used in firewalls (between living space and an attached garage), or vertical pathways such as wall cavities. The purpose of fire stop materials is to slow the spread of fire and smoke within a structure.

        I would use polyurethane caulk around the top and sides of the outdoor box in an inverted "U" shape. I'd leave the bottom edge open to allow for drainage.


    2. jeffsgta | | #10

      This has all been great help. It is kind of funny how many different way and materials you can use. Everyone has a different opinion.

      On the breaker, should I use only a GFCI breaker or a combo AFCI/GFCI breaker?

      Does it really matter if you use EMT or PVC conduit?


      1. Expert Member
        NICK KEENAN | | #11

        AFCI doesn't do well powering electric motors. If you're like me one of the primary uses of an outdoor outlet is running power tools so that's not a good application.

        There's a lot of room for regional variation and personal preference. I've always lived in damp, high-corrosion places and I wouldn't dream of using EMT outdoors, it would rust away in no time. For me it's PVC all the way. But I'm not a real electrician like Bill. EMT is what real electricians use. I could probably come up with ten reasons PVC is better and Bill could probably come up with ten reasons for EMT. I do think PVC is easier for someone who doesn't work with conduit all the time to work with.

  4. Expert Member
    NICK KEENAN | | #5

    Note that the code differentiates between wet locations, which are exposed to the weather, and damp locations, which are outdoors but sheltered. If you can put your outlet in a sheltered spot, even the equipment made for wet locations sometimes fails.

  5. joenorm | | #12

    Another vote for PVC conduit in this particular application

    1. jeffsgta | | #13

      So you would say PVC conduit and box?


  6. Expert Member
    BILL WICHERS | | #14

    I thought I'd give my reasons for recommending EMT here, which is the thinwall metal conduit:
    EMT, and it's fittings, will be slightly smaller compared with the equivalent trade side of PVC conduit. PVC conduit doesn't have an option for the handy "conduit to NM clamp" fittings that are available from EMT -- and they're available from the box stores, not even special order. Metal boxes are smaller and more durable too in many cases.

    If this were going to be something out in your yard, with an underground conduit run, I'd recommend PVC no question. For a simple sleeve through an exterior wall, EMT is generally easier to work with.

    BTW, if you're worried about a fire rated assembly, PVC isn't even an option -- you MUST use metal conduit in this case.


    1. jeffsgta | | #15

      This is true. There are not a lot of options for PVC fittings. Not planning on going underground yet, maybe in the future. I can always run PVC from the metal box later if needed.

      A concern with a metal box is rust and/or corrosion and possibly bleeding on my brick. I have had coated metal do this before. The metal box I have is a 2 gang from Sigma, is that any good? Do you have a better one you recommend?


      1. Expert Member
        BILL WICHERS | | #16

        I typically use boxes from red dot and hubbell. They’re cast aluminum boxes and I’ve never had a problem with corrosion or staining from them. I would be sure to mount them with stainless steel screws to avoid any issue with streaking though, and to avoid galvanic issues between the aluminum and regular steel screws.


        1. jeffsgta | | #17

          Will do. I will look for those brands. Thanks so much for the help. Lots of good info.

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