I have two exterior lights that need installed. I have the vinyl siding blocks and am not sure if I can just run romex to the light itself or if I have to have a 3 or 4" round light box installed before I mount the light?

This is an image of what MY siding block looks like.

enter image description here

The family handyman has an image showing just what I want to do but I do not know if that is allowed in new construction and more for a retrofit job? My only guess is they are allowed to do that because their mounting block has a recess for the fixture to attach and may even be water tight?

enter image description here

  • That mounting block appears to have a built in box. Some fixtures also have them, but a box is needed, either integral or separate. Often a round pancake box is drilled into the siding, or mounted on the surface of the siding.
    – bib
    Commented Oct 11, 2017 at 14:15

1 Answer 1


Your guess is correct. The mounting block shown in the Family Handyman image has a self contained wet rated box.

You cannot run Romex to your fixture and connect it behind the mounting block and expect it to pass inspection. The mounting block in your image would be appropriate for attaching an outdoor electrical box on top, to house a receptacle or light switch for example.

Here's a mounting block containing a wet-rated box:


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