I am considering using EPS foam insulation on my basement walls.
How do I wire the walls for the outlets? Do I need to use armoured wire? How do I cut out the channel for the wire? Is it best to use thicker furring strips and run the wire behind the drywall?
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Greetings ASENNAD,
This post in response to your question will bump the thread through the 'recent discussion' listing again.
Perhaps it will catch someones eye that can help you with advice.
Cheers
It's very simple with the right tools. You use a tool that heats up like a soldering iron to melt channels for the cable, put a few staples into the eps to hold the romex and then use expanding foam insulation in the spray can to seal up the grooves and maintain your insulating value lost by burning out the groove.
For boxes you can either get a tool specifically made for melting out the right size for an electrical box (it is adjustable for double boxes, etc.) or use the first tool and sort of freehand it. I found the best thing was to use plastic boxes and silicone them in, then fill around them with the insulation from the can. It held 95% of them, a couple I had to (shh) shoot a tapcon into the concrete behind (ICF's) to get them to hold.
Be careful with the electric melting tools. They are extremely hot, the melted foam can drip onto something and it is also very hot. The fumes are not good for you. Open all the windows and doors, wear a respirator, take a lot of breaks. When it gets a foam coating, it tends to get some nice fires going. The EPS I use has a fire retardant in it but it still burns, so if yours doesn't have this, it may be worse. The fires are very quickly and easily put out, just keep an old towel handy to smother them with.
If the expanding insulation protrudes from the grooves it is easily cut back with those long, snap off utility knives, fully extended. It can be surformed as well.
Whether you need to use one type of electrical cable or another is mostly up to your local code. I've always used romex for this.
Are you planning on using furring strips ?
Will they be 3/4" thickness with 3/4" foam ?
If so, are you using 3/4" deep electrical boxes ?
If so, this may be an electrical code issue with the number of conductors in a box.
Yes, thicker furring is a solution, but then so is studding the walls which would get you all the room you need.
carpenter in transition
I'm not planning to use it myself.The reason I asked is I saw in the installation literature the use of plain romex. I assumed it would be subject to damage from a nail or something so I was wondering if any areas required the use of armoured cable with it when only foam and drywall are used to form an exterior wall.
Where I'm running foam insulation, I'm making sure to use MC wiring. Flammable foam and conductors gnawed by mice do not make a happy combination. I've found MC as easy to cut as NM (with the right tool), much easier to handle than AC (and has better grounding), though it is tricky to route sometimes (fishing through a stud bay can play havoc with plaster keys....).
The first choice for cutting channels in EPS foam among ICF builders is a small electric chain saw. Routers are often used to cut boxes and more precision stuff. I saw one guy make a template to route for light switch and receptacle boxes. A second person with a shop vac is not a bad idea on a DIY project. Hot knives are slow but a make lot less mess.
Please check your code, this can be butt simple or a real complex hassle (your choice) what requirement does your community have? can you run romex behind sheetrock now? Then you can do so with foam.!!!
As for someone complaining about mice eating wire, why wouldn't they eat the wire if it's in fibergas or cellilous? Nah, not a real issue unless you want to use it as an excuse not to use foam.. PS check, you can get foam with Borax in it if you have a real problem, but why wouldn't you deal with the issue of rats or bugs in the house first? As for bugs, there is nothing in foam that has any nutrition! They may tunnel through it to get to their real target (wood) but I know of no bug that likes to eat plastic,,,. same with mice or rats..
The more you think about it the greater the "urban myth" factor comes into play here..
You can do any thing to put wire chases in foam, simple cuts with a saw or bore holes with a drill and an extension, (extensions) foam is real easy to work with.. I have old dull bits that I use and they work like a hot knife thru butter when boring holes for wiring.. .......(slow up a bit when I hit wood but maybe someday I'll spend a minute to sharpen them..)..
Now I'm using armoured cable simply because the old house used it, it was in good shape and I like to recycle. when I run out of Armoured I'll convert over to romex... No big deal!