How to secure cable to styrofoam

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Old 08-02-16, 07:02 AM
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How to secure cable to styrofoam

I need to run some nmd through 2" Styrofoam by cutting a little section out of it.
How can I secure the wire in the Styrofoam - can I use the NMD cable staples or will they eventually fall out?

Secondly, can the junction boxes be completely surrounded by Styrofoam?
 
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Old 08-02-16, 07:50 AM
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I would try to attach it to the wall behind the Styrofoam using a half strap.

Yes, boxes can be surrounded by Styrofoam.
 
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Old 08-02-16, 08:31 AM
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You mean put the Styrofoam on top of the cable?
Cable attached to concrete will be a lot of drilling.
Also, if I or someone ever needs to find the cable run it will be hidden.
 
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Old 08-02-16, 09:05 AM
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Yes. Put the Styrofoam over the cable.

Yes, it will be a lot of drilling, but NM cable in the US only needs to be secured every 4.5' and 8-12" from the box. Another option would be to sleeve the cable with EMT or PVC. Conduit only needs to be secured 3' from a box (or end) and every 10' along a run.

Cable is almost always buried behind/in stuff (insulation, drywall, etc) That is just a fact of life and not and issue.
 
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Old 08-02-16, 09:35 AM
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Yeah I guess the issue is that once covered in Styrofoam, the strapping has to go on top of the Styrofoam and drilled into the concrete with tapcon.
The contractor will not know exactly where the wires are.
Whereas if I rough it in after he has done the framing then I can add nail protectors.
 
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Old 08-02-16, 11:29 AM
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I would not do any wiring until all framing is done. I always tell people that framing out the walls in a basement is better done using standard 2x4's rather then just trying to use furring strips or strapping. It is MUCH easier to wire through 2x4's and you do not have the issues that you are describing. Yes, you will lose some space but it will only amount to a few square feet.

If you are bound and determined to use foam and strapping, I would for sure sleeve the cable in EMT and fasten it to the concrete wall. That will keep it away from any drywall screws and hopefully the guy installing the tapcons can figure out if he is on a pipe.
 
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Old 08-03-16, 07:19 AM
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Because it's a concrete wall below grade, the stryofoam is going on before the framing.
The alternative way would be studs in direct contact with the concrete and then fit Styrofoam in between the 16" space but that will allow cold air to circulate where the studs and possibly moisture into the wood.
 
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Old 08-03-16, 08:23 AM
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I would then install the foam (which is a very good idea) and tape the seams. Then install your 2x4 framing if front of that and wire as normal. If you want you could then even add some fiberglass for more r-value.

You could frame with 2x2's but you then be required to use metal 4x4" boxes with mud rings and get "fancy" with your cable routing, or cut into the foam to fit standard plastic boxes. This is just another reason(s) to frame using 2x4's.

This is also why I would not do any wiring until the framing is done.
 

Last edited by Tolyn Ironhand; 08-03-16 at 08:38 AM.
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Old 08-03-16, 11:21 AM
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why mud rings?
why not just dig a bit of Styrofoam out and put junction box in and nmd cable through the cable clamps?
 
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Old 08-03-16, 03:31 PM
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4x4 steel boxes require mudrings so that you can attach a device/plate to them. Otherwise the only thing you could install is a 4"x4" blank cover, or an industrial cover which would not look very good on a finished wall.

Sure you could dig a hole in the foam to install a plastic box, but you still need framing to attach the box to, and framing to secure the cable with staples.
 
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Old 08-04-16, 09:21 AM
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the receptacle just screws into the junction box directly:
Outlet Box | RONA

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I can just attach this junction box to the 2x2?
 

Last edited by ray2047; 08-04-16 at 12:14 PM. Reason: Add box image.
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Old 08-04-16, 12:08 PM
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Handy boxes such as you posted are never handy. They are just too crowded for very many wires.
I can just attach this junction box to the 2x2?
No easy way. Handy boxes are usually used for surface mount in places like unfinished basements and garages.
 

Last edited by ray2047; 08-04-16 at 02:19 PM.
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Old 08-04-16, 01:08 PM
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If you want to use 2x2's, (which I wouldn't suggest, but we have been there already) I recommend using 4x4" boxes with a bracket and 1/2" (or 5/8") mud rings. They are available in 1 1/2" deep and have much more space then a handy box. As Ray mentioned, they are not handy for anything!

4"x4" box with bracket (picture is of a 2 1/8" deep box) :

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Mud ring:

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Old 08-04-16, 01:37 PM
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Ok, wrong thing, I just meant a normal single or 2 gang box like for receptacles and switches.
That just screws into a 2x2?
 
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Old 08-04-16, 02:19 PM
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Are you talking metal or plastic?
 
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Old 08-04-16, 02:25 PM
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There are the Arlington's ONE-BOX Non-Metallic Outlet Boxes. The box mounts directly to a wood or steel stud.

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