C.E.C 300.4 Protection against Physical Damage.

[former inspector]

I am new to site but hope this is a great area to get answers and others opinions. CEC 300.4 calls out protection required, if within 1 1/4 from framing edge member. This is in the Code. No inspectors call out protection at the back of the boxes that are nearer the 1 1/4 " to edge. Some boxes come within a 1/4 to 1/2 inch from edges then you have the wiring coming into and out of the box, and no protection. Why is this missed ? I install protection on the house I build now, but my inspector thinks its a great idea but does not enforce and no consistency at the frame inspection even after I show and explain to him the requirement, its only " Great idea....but no one does it". Is anyone out here call for this protection during the Frame Inspection process ? I greatly appreciate feedback on this Code section.

 

[roger]

Unless it's under the roof boxes do not have the protection requirement that cables and raceways do.

 

[roger]

I see you're talking about where the cable or raceway enters the box. I don't guess there's enough instances of damage to warrant a code requirement.

 

[former inspector]

Unless it's under the roof boxes do not have the protection requirement that cables and raceways do.

But it is on framing inside of a house, and falls within the criteria of the required protection. Wiring is protected within 1 1/4 " of framing member edge with nail plates when passing through bores or bottom/top plates. The back of plastic installed boxes needs to be protected because the wiring going into and out of the box is very close, closer then the distance of 1 1/4 ". One City in Bay Area calls for this protection and I find no other Jurisdictions do.

 

[former inspector]

I see you're talking about where the cable or raceway enters the box. I don't guess there's enough instances of damage to warrant a code requirement.

Hi Roger, yes totally agree but it is stated in the Code and that falls under protected requirements. I try to follow Code and install per requirements, but Its a overlooked area. I have some areas where the box and fill and wires coming out are within 1/4" of edge of framing with a deeper box. I protect everything per Code. I don't use my own opinion, which is in alignment of yours, but install per Code requirements. I greatly appreciate your feedback....

 

[former inspector]

The Electrical handbook used to show a depiction of wiring installed parallel to framing members edge with the 1 1/4 " distance shown, but did not show the box that the wiring was going into and out of. Usually most if not all installs in residential are plastic unprotected boxes.

 

[infinity]

If you use the KO nearest to the stud then you don't have the 1.25". I've never seen anyone enforce this.

 

[electrofelon]

I have thought about this, and I guess in my head I thought there was a written exception to cover this but I guess it's a mental fabrication?

 

[former inspector]

There are exceptions to the code and they are stated. That is my problem here in California, Palo Alto calls this , per my Electrical contractor and they are correct in calling for this protection, Mountain View is now starting to call it, they are trying to be consistent, spoke with my inspector and he said some guys call it and some don't and he had me protect on my last two homes, but they are now consistent and calling for protection at boxes. They are correct. I am just trying to find out with all the folks out there, if they are providing protection per this code requirements. I have talked with other Building Officials who agree, its required. My feedback from professionals I have spoken to is 'YES' it is required unless you meet the exceptions. Everywhere I build now I protect the boxes but I am finding that many inspectors do not and ignore the code requirements, which does not go to far for being consistent . As a retired City Inspector I started informing electrical contractors that they need to start protecting this location. Thank you everyone for jumping on here.....

 

[Seven-Delta-FortyOne]

You’re misunderstanding the Code.

1 1/4” is from the outside edge of the framing member, depth wise. This is why if you drill 7/8” holes in the dead center of the stud, no nail plates are required.

It’s not a horizontal measurement, it’s a depth measurement.

And there’s no Code provision for protection on the backside of Carlon boxes, so you can’t make one up.

 

[infinity]

And there’s no Code provision for protection on the backside of Carlon boxes, so you can’t make one up.

The 1.25" measurement is in two directions from the face of the stud back 1.25" and from the face edge of the stud 1.25" to the side. That's why the cable in the KO next to the stud is a problem because it is still required to be 1.25" away from the front edge of the face of the stud and it isn't.

 

[former inspector]

Infinity , correct !!

 

[acrwc10]

To cover the back of the box Palo Alto accepts a 4-11/16" blank cover screwed to the stub behind the box. Other than that you are arguing to a brick wall. You could also space your boxes off the stud with a block, this gives the 1-1/2" space to not need the plate.

 

[former inspector]

and with that we still have box fill inside that is also close

 

[former inspector]

That's what we are doing is installing plates at face of stud to protect box, and those also get taken off periodically because of planing the studs.

 

[nizak]

I think the intent is to protect the NM cable from a penetration into the stud i.e. drywall screw, etc.


I have over the years found nails used for vinyl siding penetrating the back side and into PVC boxes.

I would suspect in almost 30 years of doing residential work at some point a nail has hit the NM where it enters the box but wasn’t strategically placed to cause a known fault

Actually, quite a few times I’ve found them inside the boxes.

 

[acrwc10]

That's what we are doing is installing plates at face of stud to protect box, and those also get taken off periodically because of planing the studs.

check your personal messages at the top of your screen.
I can't imagine the coming back to check box fill,

 

[former inspector]

I have seen lath staples right through and into the box on backside

 

[curt swartz]

The former PA inspector is the only inspector I have encountered enforcing this. When she first started enforcing it we got in a heated debate. She said she brought it up at the local inspectors meeting and all the inspectors agreed with her. I asked why she was the only inspector enforcing it then. Later I contacted inspectors that were at the meeting and was told they did NOT agree with her on this.

 

[infinity]

I have over the years found nails used for vinyl siding penetrating the back side and into PVC boxes.

I would suspect in almost 30 years of doing residential work at some point a nail has hit the NM where it enters the box but wasn’t strategically placed to cause a known fault

Yes siding guys are famous for finding that cable or box with a long nail. Around here most new houses are exterior wall framed with 2X6 lumber so that is no longer a problem.