Discussions

I have new construction 2x6 wall with 1&1/2” styrofoam on the exterior. The siding will be vinyl with vinyl mounting blocks. What is the best way to mount receptacle boxes and light fixtures? I have a couple ideas but am curious to see if there are some better ways.  
Thanks

For recepticles and lights you can get the mounting boxes at your local supply store (McMunn, Home Hardware, Home Depot, etc.). Make sure you use an appropriate sealant on the back to ensure the air barrier is preserved. For conduit or any other holes you need to create (sump pump, ultilities, etc.), cut a piece of PVC trim board (or equivalent, make sure the thickness is about equal to your vinyl siding depth. Wood blocking in the pic is just for stability, remove it when you install the siding. Spray foam all openings when complete.

Good info for finishing but I’m actually wondering what people do to get the metal electrical boxes and octagon light boxes out to the face of the mounting blocks.  
Should I cut a section of styrofoam out and replace it with wood blocking to mount the electrical boxes? Or is there another way?

Most hardware stores will have something called a box extension, it screws onto main box 2 corners and provides 2 more corners to mount to further out, I assume most people use those and maybe a combination of multiples if gap is deep.