NMSC in SIP construction

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DHefler

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In a structural insulated panel, would fishing romex through PVC conduit into a metal box be legal? Wouldn't the cable need to be clamped in the box per 314.17(b)? Any help or suggestions would be apprciated as this is the first SIP constructed house I have wired.
 
DHefler said:
In a structural insulated panel, would fishing romex through PVC conduit into a metal box be legal?
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In my opinion, yes. Why would you want to? Just fish the romex directly into the box and install a normal romex clamp.

Any help or suggestions would be apprciated as this is the first SIP constructed house I have wired.
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I have wired one, the house I worked in had chases every so many feet for wiring. We used Bowers Steel Stud boxes screwed to the OSB, they worked pretty good. We just fished our romex into the chase and called it a day.

Hope this house was bid well, they can be a treat. ;)
 
Thanks for the reply George. To clarify, this panel manufacturer provides electrical chases by imbedding PVC, either 1/2" or 3/4", in the polyurethane core. They'll place the chases anywhere you want them, horizontal or vertical. They say they'll also terminate this PVC into a steel box for $10 more a hole. I'm not aware of any steel box that has a knockout in the top for conduit and provisions to clamp romex. My thinking is this method would not be legal, if you don't secure the romex to the box. The only alternative I can think of is to have them imbed the PVC with no box and router the openings on site and use a regular romex box, secured to the OSB, as you suggested. No worries about the bid on this one, as it's my own home.
 
I should rephrase my answer: No, I don't think it's technically legal to omit clamping the cable, but I don't think it is a stonable offense.

I'd just have them install the PVC sleeves, and fish through them, in your own NM box with clamps already a part of them. Unless you want to call the local AHJ and get their view on it.

What part of the country are you building this house?
 
In a metal box, a ground screw can do a great job of keeping an NM cable in it without a clamp.
 
George,
The House is in rural Arizona, no inspection other than the service, but being an electrician, I didn't want my own home to not be up to code. Knowing some of my fellow electricians, stoning is a possibility. LOL

Larry,
Never thought of that, but it would be pretty darn hard to pull the cable out of the box with the ground around the screw. Just not too sure that would satisfy the "cable shall be secured to the box" though.

Thanks for your input guys. Appreciate all the help I can get.
 
I know when running romex through emt to a box........the open end(let's say the top of a conduit running down a concrete wall in a basement) has to have a connector or some type of bushing. We use the yellow push on ones.
Arlington EMT50 http://www.aifittings.com/b_1.htm


I would think the same goes for PVC
 
It might be a pain... but why can't you just screw an NM clamp into the back of the box like in a regular metal NM box? You might have to drill and tap a few holes but it never says how or where it has to be clamped to the box.

How about connecting to the box by threading an nm-box connector from the inside into a threaded coupling on the outside and threading a PVC adapter into that?

Why is it no one makes an NM clamp that that threads on like a bonding bushing or any of the other fittings I usually wish they made?
 
If you've never tried it....A 3/8" metal romex connector will thread nicely into the end of a 3/4" sch 40 PVC male adapter. Don't know if it's legit, but it anchors the NM nicely.
steve
 
Thanks for the ideas. Mounting a NM clamp to the back of each box or Hillbilly's suggestion of a romex connector in the end of the PVC adapter should do the trick.
 
Usually when we have done homes like this we get them with NO boxes or Holes or anything....we have done MANY in Wintergreen,VA at the resort.

Basically we have to use a circular saw to cut our box openings...usually just large enough for the box....BUT no where to actually staple them....since well it is all foam.....

What we had to do was confront the local AHJ and present that the foam that Dow Chemical makes is rated for firestop AND dries hard....so it itself will secure and support the wires as they enter the plastic boxes we use for this application.

In your case......I have seen a few homes with the PVC piping already run in the walls and the BOXes are already in the wall....no room to get below them, under them...anything....just PVC running into the box......brings up issues I wont go into....BUT very hard to terminate them entering the box in that style....now if they did the boxes and left a larger GAP around them....you could do as Pierre stated and have the PVC end before it gets to the box and then bring them in to the box through standard connectors... I dont think anyone would gripe about the support issue on that end.

Problem is I usually see these with NO room to even get to the box....but again different manufacturers I guess.

AS for the GAPS around the boxes when we cut our larger holes and holes for fishing wires...since they usualy dont come with any....yeah...its a pain in the BUTT to wire them......anyway the Dow Chemical Great Stuff Orange foam is fire rated.....fills the areas fine...when it tries it cuts off with a saw flush and no gaps.........the AHJ agreed and it became the standard for doing them in that area of Virginia that is getting the "GREEN" homes.

Just thought it may be helpful to you.
 
hillbilly said:
If you've never tried it....A 3/8" metal romex connector will thread nicely into the end of a 3/4" sch 40 PVC male adapter. Don't know if it's legit, but it anchors the NM nicely.
steve
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"That's one of those things that make you stop and say 'Hmmm.'" ~ Arsenio Hall
 
Paul, thanks for the input. I was fooling around with a few parts and found that the threaded half, cut off a PVC female adapter, will join a PVC male adapter to a 3/4" NM connector quite nicely. Enough room for a 12-3 and a 12-2 with some left over. Have to use a deep box to have enough room for a GFCI or a dimmer, but it works. Hmmm!
 
I found the rotozip to pay for itself in the SIP house I did, too. You can make a hole that looks good, fits the box snugly, and as a result, stops a draft fairly well too. Just throwing that out there. :)

Can't imagine using a circular saw for it - but if there was no chase, I can see why that would be the tool of choice. I was under the impression that such a gash would torpedo it's structural soundness.
 
George, I questioned the manufacturer about the size of hole you can cut in the panel and to my surprise you can make huge openings with little effect. He said as long as you leave 1 foot at top, bottom and sides it's OK.
 
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