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Below is my current understanding of end-to-end project for installing a garage security flood light. Wonder whether this is NEC 2017 code compliant or not. Any suggestions/recommendations are welcome!

Context:

  1. An outlet is protected by 20 amp breaker
  2. There is no attic access (another room above)

Outside:

  1. Install 4 in. PVC Round Weatherproof Box with Five 3/4 in. Outlets
  2. Glue 2 male adapters on 6" PVC and stick it through the wall
  3. Use THHN to go from the round box to a junction box
  4. Use 3/4 in. ACC Non-Metallic Strain Relief in central outlet [goes into a wall]
  5. Use UF-B 12/2 cable to go through the wall

Questions:

  1. How to screw something to the external wall like this (with and without a stud)?
  2. Should I cover all 4 remaining outlets? Or should I leave the bottom one open?

enter image description here

Inside:

  1. Use Wiremold 700 series to extend a ceiling outlet (protected by 20 amp breaker), use it as a conduit and a junction box
  2. Use 12/2 THHN wires from the outlet to the junction box
  3. Use UF-B 12/2 cable 12/2 THHN wires to go through the wall (in PVC pipe)

Questions:

  1. I would like to have an ability to turn off this security flood light. Is it allowed to install a switch in unreachable location (> 9 feet)?

enter image description here

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  • The Halex connector is not Listed for UF cable. "Use to connect S, SO, ST, SJ, SJO, and SJT cord..." halexco.com/… . I would likely make a pvc nipple.
    – NoSparksPlease
    Commented Feb 20, 2021 at 16:42
  • Thank you @NoSparksPlease, this makes sense. What can I use instead to connect to such box?
    – ZakiMa
    Commented Feb 20, 2021 at 22:31
  • Two screw connectors would work. I would glue two terminal adapters (male adapters) on a +/-6" piece of PVC and stick it through the wall, that way you can run the same THHN through it that you are running in the V700 Wiremold. Actually I developed an aversion to V700 after doing so much work in old schools that I likely would use a Raco 187 extension at the outlet box and run PVC or EMT all the way to the round box.
    – NoSparksPlease
    Commented Feb 20, 2021 at 23:56
  • This is very interesting idea! Am I allowed to run THHN wires to outside? Is the round box itself considered a wet location? Or since it is fully insulated it is okay to use THHN wires?
    – ZakiMa
    Commented Feb 21, 2021 at 1:59
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    Astute of you to catch the tech difference, the reality is nobody makes just THHN rated wire any more, it is all dual rated and electricians get sloppy not going into detail clarifying the difference/nondifference. mysouthwire.com/medias/sys_master/product-specifications/… generalcable.com/na/us-can/products-solutions/construction/…
    – NoSparksPlease
    Commented Feb 21, 2021 at 5:32

1 Answer 1

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A surface mount box can be attached to the exterior siding (what is the siding?) In some cases I like to cut the siding an inset the box and screw it to the sheeting OR cut through the sheeting and make the box flush mount (old work box could be used in this case). Since you have the UF a surface mount is fine I usually use 2 screw clamps, cheaper than a CGB and 2 screw clamps are listed for the UF. a CGB may or may not be listed for use with flat cable it depends on the seal some are hard plastic and those are not on the ones I have used and some are a soft neoprene and some of those are. But I would use the cheaper 2 screw clamp. All the unused holes are required to be plugged if you are concerned with water accumulation it is acceptable to drill a drainage hole in the bottom of the box. The maximum hole size is 1/4”. As far as height NEC 404.8.A all switches and circuit breakers used as switches limit the switch to 6’7”. There are switches that can be up high but these are a specific type not a common snap switch.

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  • What is the example of 2 screw clamp? Something like this? homedepot.com/p/…. Is it allowed to use it for non-metal boxes?
    – ZakiMa
    Commented Feb 20, 2021 at 19:57
  • Thank you for pointing to a NEC article about switches.
    – ZakiMa
    Commented Feb 20, 2021 at 20:01
  • Re: exterior siding. It looks and feels like wood shingle siding. So, would it be fine just to attach to it?
    – ZakiMa
    Commented Feb 21, 2021 at 5:43
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    Yes you can attach the box directly to the siding. When I do this I seat the top and sides not the bottom so if by chance some water gets behind the box it will drain and not end up inside the wall. To answer the above comment about THHN, almost all THHN has been dual rated for ~20 years some main US brands going back much further the dual rating today is usually THWN-2 , +additional types but the THWN provides the wet location protection when going outside similar to UF. The difference is the THWN requires conduit the whole way box to box where UF only requires a bushing or clamp at the box
    – Ed Beal
    Commented Feb 21, 2021 at 17:08
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    No clamp is required when conduit is used box to box.
    – Ed Beal
    Commented Feb 22, 2021 at 13:00

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