attach plastic box with metal screw through side ?

[RustyShackleford]

I need to extend a circuit by splicing into a 1-gang box containing a duplex outlet. I need to go to a bigger 1-gang box for box-fill, but there's no old-work box that's big enough. So I can pull some drywall so I can nail in a large enough new-work box. Or I can mount it in a different way; the question is, will this pass code ? I'd just cut off the nailing ears, insert the box through the existing drywall hole, and attach it using a screw (or two) through the sides of the box into the stud. I'm thinking maybe the problem would be the metal screw head inside the plastic box. Maybe ok if I ground the screws ? Cover 'em with RTP ? Or forget the screws and glue the thing to the stud ? Anyone ever dealt with this ? Maybe easier just to patch some drywall ...

 

[jumper]

Try these:

http://www.smartboxinc.com/electrical_boxes.php

 

[infinity]

If the box isn't designed like the one Jumper posted then forget the screws through the side. Use a different type of box or just secure it using a different method.

 

[RustyShackleford]

Try these:

http://www.smartboxinc.com/electrical_boxes.php

Thanks. Never see those before. Are they readily available (in local supply stores) ?

 

[1793]

Thanks. Never see those before. Are they readily available (in local supply stores) ?

My supply house does not stock that exact box but they do have a box very similar, it is a "Sliderbox". :thumbsup:

 

[Ponchik]

Besides 110.3 what is the code violation if installing boxes like the OP?

 

[Little Bill]

Thanks. Never see those before. Are they readily available (in local supply stores) ?

Arlington makes one too.

http://www.galesburgelectric.com/Arlington-F101-ONE-BOX-with-Side-Angled-Screws.html

 

[jumper]

Besides 110.3 what is the code violation if installing boxes like the OP?

This section is often cited:

314.23(B)(1) Nails and Screws. Nails and screws, where used as a
fastening means, shall be attached by using brackets on the
outside of the enclosure, or they shall pass through the
interior within 6 mm (1⁄4 in.) of the back or ends of the
enclosure. Screws shall not be permitted to pass through the
box unless exposed threads in the box are protected using
approved means to avoid abrasion of conductor insulation.

 

[infinity]

I'm not seeing how that would apply to mounting a plastic box with two metal screws through the side.

 

[tkb]

This section is often cited:

314.23(B)(1) Nails and Screws. Nails and screws, where used as a
fastening means,...Screws shall not be permitted to pass through the
box unless exposed threads in the box are protected using
approved means to avoid abrasion of conductor insulation.

I take this to mean nail or screws through the box from one side to the other as in the nail on type. The code article mentions protecting the threads. This would not be nessesary if the screws simply were through the side of the box next to the stud.

 

[kwired]

I take this to mean nail or screws through the box from one side to the other as in the nail on type. The code article mentions protecting the threads. This would not be nessesary if the screws simply were through the side of the box next to the stud.

I used to think that myself, but read it carefully, exactly what the wording is intended to mean is not that clear at all. It can be interpreted to mean no nails or screws in the sides of the box at all except for the back 1/4 inch of the box sides. This makes some sense for narrow device boxes where device terminals may be real close to contacting the mounting screws. Makes no sense at all for something like a 24x24 pull box, but as worded it applies there also.

 

[Ponchik]

The code section 314.28(b)(1) says "through the box" and "exposed threads are protected". Well, once the screws goes through the side wall into the 2x4 then there is no more thread left to damage the wires.

I think this code section is talking if the screw or the nail is going from one side of the box through the inside and out the other side. In that case it will have exposed threads in the box.

 

[George Stolz]

That's brilliant! I had never looked that close at this before - I agree, as written, it only applies if the screw starts on one end of the box, passes through the interior and exits the other side of the box. I always thought it prohibited a screw through one side of a box as well!

 

[infinity]

I used to think that myself, but read it carefully, exactly what the wording is intended to mean is not that clear at all. It can be interpreted to mean no nails or screws in the sides of the box at all except for the back 1/4 inch of the box sides. This makes some sense for narrow device boxes where device terminals may be real close to contacting the mounting screws. Makes no sense at all for something like a 24x24 pull box, but as worded it applies there also.

It means something like this regarding nail and a metal box which would be code complaint:

 

[iwire]

In my area I have often found old metal basic single gang switch boxes nailed to the studs with nails that went all they through the both sides of the box but they would be located all the way at the rear so they complied with the code section above.

 

[iwire]

It means something like this regarding nail and a metal box which would be code complaint:

Thank you, that is exactly what I have found in old buildings.

 

[infinity]

A plastic box is required to comply 314.43 with which means that it must contain a provision to keep the conductors from contacting the screws.

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

 

[George Stolz]

This section changed in the 2005 to clarify that a screw in one side wasn't being addressed. My rememberer was still in the '02 on this.

 

[kwired]

That's brilliant! I had never looked that close at this before - I agree, as written, it only applies if the screw starts on one end of the box, passes through the interior and exits the other side of the box. I always thought it prohibited a screw through one side of a box as well!

Well I would like to know just exactly what it means, and don't think it is all that clear. I have mounted 4x4 boxes through the two holes near the front edge of the side walls for nearly 25 years and then used a mud ring to make it a device box. Very common for me to do this in installations using MC cable. Never had an inspector even think about whether or not it was wrong, and have had virtually no performance problems of the method that I am aware of. More recently have had an inspector tell me he doesn't want to see that anymore - "those holes are not listed for that purpose"??? He let them go on the installation at that time but I told him I didn't think that was an NEC violation. Have not encountered this situation since then, but it will come up again someday and if I am to use my old method I want to have good support as to why it is allowed. If I find good support that says it is not allowed, I will not install that way anymore.

The only thing I can find that maybe disallows it is dependent on how you interpret 314.23(B)(1).

 

[infinity]

Thank you, that is exactly what I have found in old buildings.

Yup, pretty standard practice around here for houses built in the 50's.