05' NEC 314.23(B)(1) Would it be allowable "Let's say" to fasten a Nonmetallic box (In a tight location where normal manufacturer installed fastening is not possible) with screws toward the front edge interior? I see this a lot and have done this before. What are your interpretations? Thanks.
Fastening NM Boxes
- Thread starter triphase
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bphgravity
Senior Member
- Location
- Florida
Re: Fastening NM Boxes
I believe what you are desribing is a direct violation of this section.
I believe what you are desribing is a direct violation of this section.
ty
Senior Member
- Location
- 3rd Rock from the Sun
Re: Fastening NM Boxes
There are boxes specifically made with the screws pre-installed. P&S I'll have to search for a link.
There are boxes specifically made with the screws pre-installed. P&S I'll have to search for a link.
electricman2
Senior Member
- Location
- North Carolina
- Occupation
- Retired Electrical Contractor
Re: Fastening NM Boxes
I have done this using round head screws although technically not allowed as the intent of this section I believe is to prevent conductor insulation damage from exposed metal fasteners.
I have done this using round head screws although technically not allowed as the intent of this section I believe is to prevent conductor insulation damage from exposed metal fasteners.
- Location
- New Jersey
- Occupation
- Journeyman Electrician (retired)
Re: Fastening NM Boxes
Here is one such box:
Here's a link for more info:
http://www.aifittings.com/whnew78.htm
I think that the head of the screw argument is lame. Metal boxes have 10/32 screws holding in a metal clamp and these don't seem to compromise the wiring.
Here is one such box:
Here's a link for more info:
http://www.aifittings.com/whnew78.htm
I think that the head of the screw argument is lame. Metal boxes have 10/32 screws holding in a metal clamp and these don't seem to compromise the wiring.
bill addiss
Senior Member
Re: Fastening NM Boxes
Here's a picture of the 'Original' Smart Box:
more info can be found at www.Smartboxinc.com
Bill
Here's a picture of the 'Original' Smart Box:
more info can be found at www.Smartboxinc.com
Bill
electricman2
Senior Member
- Location
- North Carolina
- Occupation
- Retired Electrical Contractor
Re: Fastening NM Boxes
nails are permitted if at least ?" from end or back. So are screws if threads are protected. Go figure.
electricman2
Senior Member
- Location
- North Carolina
- Occupation
- Retired Electrical Contractor
Re: Fastening NM Boxes
Thats why the rules are so restrictive for plastic boxes.
Accidental contact of a bare conductor with a screw in a metal box would open the OCPD. (assuming the box is properly bonded). This would not happen in a non-metallic box. You would end up with an energized screw.
Thats why the rules are so restrictive for plastic boxes.- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Re: Fastening NM Boxes
I believe this is another case of thinking the NEC says something it does not actually say.
314.23(B) does not have different rules for metallic and non-metaliic boxes. There is one set of rules regardless what the enclosure is constructed of.
Screws and nails that PASS THROUGH (from the outside of one wall, through the box, and exiting the opposite wall) the box must be placed in an area that does not interfer with the mounting of a device into the box/enclosure. This is the part of the reason for the requirement that these items be located not more than than 1/4" from the back or ends (top and bottom) of the box. The only special provision for screws is that only exposed threads must be covered.
I can find nothing in the code that addresses screws that do not pass all the way through a box. For screws that start in the box and exit only one wall, there is nothing that says they even need to be bonded. For example look at an old-work box with internal mounting clamp screws or one with cable clamp screws.
I believe this is another case of thinking the NEC says something it does not actually say.
314.23(B) does not have different rules for metallic and non-metaliic boxes. There is one set of rules regardless what the enclosure is constructed of.
Screws and nails that PASS THROUGH (from the outside of one wall, through the box, and exiting the opposite wall) the box must be placed in an area that does not interfer with the mounting of a device into the box/enclosure. This is the part of the reason for the requirement that these items be located not more than than 1/4" from the back or ends (top and bottom) of the box. The only special provision for screws is that only exposed threads must be covered.
I can find nothing in the code that addresses screws that do not pass all the way through a box. For screws that start in the box and exit only one wall, there is nothing that says they even need to be bonded. For example look at an old-work box with internal mounting clamp screws or one with cable clamp screws.
- Location
- Massachusetts
Re: Fastening NM Boxes
Jim I have brought this up before and no one seemed to see it that way. I agree with you entirely.
IMO these screws..
...do not pass through the box and therefore are not covered by 314.23(B) at all.
This next picture shows nails passing through the box that 314.23(B)(1) allows.
And finally nails passing through a box that 314.23(B)(1) prohibits.
Jim I have brought this up before and no one seemed to see it that way. I agree with you entirely.
IMO these screws..
...do not pass through the box and therefore are not covered by 314.23(B) at all.
This next picture shows nails passing through the box that 314.23(B)(1) allows.
And finally nails passing through a box that 314.23(B)(1) prohibits.
sandsnow
Senior Member
- Location
- Southern California
Re: Fastening NM Boxes
Bob
Did you drill the holes or are those factory holes?? The ones with the nails. I did not think boxes like this were still made
Box number complies.
edit: box number one complies.
[ January 16, 2006, 02:02 PM: Message edited by: sandsnow ]
Bob
Did you drill the holes or are those factory holes?? The ones with the nails. I did not think boxes like this were still made
Box number complies.
edit: box number one complies.
[ January 16, 2006, 02:02 PM: Message edited by: sandsnow ]
- Location
- Massachusetts
Re: Fastening NM Boxes
They are just old works I had in my basement, they are no more than a couple years old.
No drilling.
They are just old works I had in my basement, they are no more than a couple years old.
ryan_618
Senior Member
- Location
- Salt Lake City, Utah
Re: Fastening NM Boxes
But if you are going to bring up the "pass through the box" vs. not passing through the box, then any nail or screw that doesn't pass through th ebox doesn't comply. 314.23 gives you two ways of mounting a box with nails or screws:
1) Brackets on the outside, or
2) Nails and screw that "pass through the box" and meet the 1/4 rule.
I'm not saying I like what I am saying, but that is the way I read it.
But if you are going to bring up the "pass through the box" vs. not passing through the box, then any nail or screw that doesn't pass through th ebox doesn't comply. 314.23 gives you two ways of mounting a box with nails or screws:
1) Brackets on the outside, or
2) Nails and screw that "pass through the box" and meet the 1/4 rule.
I'm not saying I like what I am saying, but that is the way I read it.
sandsnow
Senior Member
- Location
- Southern California
Re: Fastening NM Boxes
Thanks Bob
I'll have to look at HD next time. Would be great to use as hands on to explain this section.
Thanks Bob
I'll have to look at HD next time. Would be great to use as hands on to explain this section.
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