Fire rating of plastic cut in boxes

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sandsnow

Senior Member
What if you secure the cut in box to the stud, if you are good you can cut in tight. no gap.

Theoretically....yes. Having the box secured is how other boxes are tested.
Technically.......no. Cut in boxes are not tested in that manner. AFAIK
Realistically....... I remember something about a screw or nail head are not supposed to exposed inside a non metallic box or recessed a quarter inch. I just can't put my finger on it. Maybe someone else can find it, if it exists.
Without screwing the box to the stud from the inside, how would you attach it?
 

wwhitney

Senior Member
Location
Berkeley, CA
Occupation
Retired
Are those rated for use in rated walls?
I don't know anything about them other than what is on the web. Arlington's website doesn't make it clear. Their line drawing

http://www.aimedia.co/media/line-drawings/F101.pdf

says "Class 2H WC" around the UL mark, does that 2H mean it can be used in a 2 hour rated assembly? Several other websites that carry the Arlington One Box say it has a 2 hour rating.

Cheers, Wayne
 

Sierrasparky

Senior Member
Location
USA
Occupation
Electrician ,contractor
I don't know anything about them other than what is on the web. Arlington's website doesn't make it clear. Their line drawing

http://www.aimedia.co/media/line-drawings/F101.pdf

says "Class 2H WC" around the UL mark, does that 2H mean it can be used in a 2 hour rated assembly? Several other websites that carry the Arlington One Box say it has a 2 hour rating.

Cheers, Wayne

IF it is stamped "Class 2H WC" then that means it is listed for a 2hr rated wall. I would generally only need those in a 1 hr wall so they should be good to go.
 

kwired

Electron manager
Location
NE Nebraska
Theoretically....yes. Having the box secured is how other boxes are tested.
Technically.......no. Cut in boxes are not tested in that manner. AFAIK
Realistically....... I remember something about a screw or nail head are not supposed to exposed inside a non metallic box or recessed a quarter inch. I just can't put my finger on it. Maybe someone else can find it, if it exists.
Without screwing the box to the stud from the inside, how would you attach it?
I don't know the section off top of my head either, but believe what you said is mostly correct...

Looks good to me.
I always liked Arlington, they make a lot of products as solutions to real world situations.

and I believe that code mentioned before has a lot to so with the development of Arlington's "One Box" series, without that code there wouldn't be as much need for this product.
 

Ponchik

Senior Member
Location
CA
Occupation
Electronologist
Theoretically....yes. Having the box secured is how other boxes are tested.
Technically.......no. Cut in boxes are not tested in that manner. AFAIK
Realistically....... I remember something about a screw or nail head are not supposed to exposed inside a non metallic box or recessed a quarter inch. I just can't put my finger on it. Maybe someone else can find it, if it exists.
Without screwing the box to the stud from the inside, how would you attach it?


314.23 (B)(1)
if the nail or the screw goes THROUGH the box it has to be within 1/4" of the back.

It will depend how you interpret "THROUGH the box"

The comments in the hand book mention "coarse screw thread" but if all you show after your installation is the the head screw, IMO your installation is fine and you don't need the special boxes from Arlington.
 
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kwired

Electron manager
Location
NE Nebraska
314.23 (B)(1)
if the nail or the screw goes THROUGH the box it has to be within 1/4" of the back.

It will depend how you interpret "THROUGH the box"

The comments in the hand book mention "coarse screw thread" but if all you show after your installation is the the head screw, IMO your installation is fine and you don't need the special boxes from Arlington.
I agree, but there is still some strict interpretations and that maybe provides a need for special boxes mentioned. It is a little harder to reject something designed (and maybe even listed) for the purpose. Same can possibly be said for many other handy products that Arlington makes.
 

sandsnow

Senior Member
Found it. The section for screws being recessed is here......

314.43 Nonmetallic Boxes. Provisions for supports or other mounting means for nonmetallic boxes shall be outside of the box, or the box shall be constructed so as to prevent contact between the conductors in the box and the supporting screws.

Interesting that it doesn't read metal fasteners. It would appear it doesn't apply to nails?????
 

Sierrasparky

Senior Member
Location
USA
Occupation
Electrician ,contractor
Found it. The section for screws being recessed is here......

314.43 Nonmetallic Boxes. Provisions for supports or other mounting means for nonmetallic boxes shall be outside of the box, or the box shall be constructed so as to prevent contact between the conductors in the box and the supporting screws.

Interesting that it doesn't read metal fasteners. It would appear it doesn't apply to nails?????

That is because someone on the CMP was pissed people were using screws to secure those boxes from the inside.

Seems you can use screws in a metallic box from the inside.
 

jumper

Senior Member
Seems you can use screws in a metallic box from the inside.

If you are talking about using screws in the little holes on the side of a 4" x 4" metal box, technically that is a violation, although we have all done it. No one I know has ever been called on it.

Those holes are actually for mounting clips that are used to fasten devices to the box, not for mounting the box.
 

Ponchik

Senior Member
Location
CA
Occupation
Electronologist
If you are talking about using screws in the little holes on the side of a 4" x 4" metal box, technically that is a violation, although we have all done it. No one I know has ever been called on it.

Those holes are actually for mounting clips that are used to fasten devices to the box, not for mounting the box.

I drill my own holes between the KOs.

If I know the screw that is installed from the inside will not harm the conductors, I don't see what the big fuss is about. Sometimes, AHJ gets bent out of shape over minor stuff.
 

roger

Moderator
Staff member
Location
Fl
Occupation
Retired Electrician
Well, there is 314.23(B)(1), of course that is addressing screws passing through the box. OTOH, it does not say screws installed in the box is allowed.

Roger
 

kwired

Electron manager
Location
NE Nebraska
If you are talking about using screws in the little holes on the side of a 4" x 4" metal box, technically that is a violation, although we have all done it. No one I know has ever been called on it.

Those holes are actually for mounting clips that are used to fasten devices to the box, not for mounting the box.

Sorry Jumper I calling for a code cite on that. :)

Agreed, what code is violated?

I've been told I can't use those holes for mounting the box - after having used them for 20+ years for that purpose:roll:

I don't recall specifically but would guess they probably cited 110.3(B).

Same AHJ never gives you any trouble if you drill your own mounting holes elsewhere in a box - so drill your own holes right next to the existing ones and you may be OK?

Totally senseless, and coming from an AHJ that I usually support most of their methods and practices. I guess those factory holes are intended to attach mounting ears - still a mounting method though :rant: Someone got into their heads and convinced them this is how it should be, as they are usually fairly consistent statewide on some issues like this.
 

Strathead

Senior Member
Location
Ocala, Florida, USA
Occupation
Electrician/Estimator/Project Manager/Superintendent
Well, there is 314.23(B)(1), of course that is addressing screws passing through the box. OTOH, it does not say screws installed in the box is allowed.

Roger

that would cover it Roger, thank you. OTOH, interpret ""ends of the enclosure" for me. I don't think I understand what they mean by ends.
 

jumper

Senior Member
Sorry Jumper I calling for a code cite on that. :)

Agreed, what code is violated?

Well, there is 314.23(B)(1), of course that is addressing screws passing through the box. OTOH, it does not say screws installed in the box is allowed.

Roger

Roger got the section I was thinking of, but as he points out it does not apply directly because of the word "through."

Ooops.
 
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