My electrician is out of town for the week, but its time for rough in. Neither of us has done ICF walls before. He gave me a heads up to start pulling wires without him, but we’re not sure about which boxes to use in ICF walls.
My original thought was to use metal boxes with built in clamps. We had a conversation this morning – his thought was to avoid metal, and the boxes I could find might not be big enough for many wires anyway. He recommended plastic boxes w/plaster rings for attachment.
The big question is: How do you clamp the wires? Is there a simple clamp that would fit in the box that would meet the requirement to attach the wires within 8″ of the box? I’m thinking there is no easy solution for clamping outside the box, and foaming the wires in place won’t pass our local inspector.
Replies
Brian
If foaming won't pass the inspector then you need an inspector with a grain of common sense. How likely is that?
Ron
The funny part is my electrician IS the inspector, just in another county. I mentioned ICFs and he at least knew what they were. The good news is I've always sailed through inspections since he knows every jot and tittle of the code. (except our county's interpretation of gray areas)
But the inspector here has a reputation of being unreasonable. And when I mentioned ICFs to the permits and inspections department locally, it was like I had sprouted another head.
So I need to be thorough in my approach, and maybe over-thorough, cause I'm not moving to another county...
Treat every person you meet like you will know them the rest of your life - you just might!
What the inspectors are looking for are secure boxes and wiring with a clearance factor for the wiring.
You can use either the metal or plastic 90 degree offset boxes - with the flange to allow attachment to the built-in stud in the ICF or you can mount a box any where with tapcons after scooping out a hole. The face of the box you choose should protrude from the face of the ICF just as if it were nailed to a regular framed wall. There are mud rings or extensions for that purpose. In fact, if you use nothing less than a 2-gang box for your single work, with a single gang mud ring, you have all sorts of room in the box for your wiring.
Rout the channel for wiring all the way to the concrete and hold it in place with expanding foam. Some (probably most) inspectors want to be sure nothing moves and will require a clamp at 8" from a plastic box and every 4 feet. 1 1/4" clearance depth is still required and a simple conduit strap works every time.
Wire paths are best when kept away from the drywallers so routing halfway between the "studs" works for me.
Thank you Ralph, very helpful.
Treat every person you meet like you will know them the rest of your life - you just might!