300.4 D - "Sleeving a cable between wall plates"

[Bahnsen]

I'm running aluminum 4/0 SER up my 2x4 wall. Because the cable is 1.5" in diameter, even if placed in the centerline of the 2x4 stud it doesn't comply with the NEC requirement of 1 1/4". I know that NEC 300.4 D specifies that a steel "sleeve" that is 1/6" thick serves as protection. My question is, can I use EMT (of an appropriate fill size for the wire) as a "sleeve" between the top and bottom plate of the wall to protect that portion (I understand that the wire also needs to be protected where it passes through the top/bottom plates). If so, do I have to install bushings on the ends of the EMT even though I don't really see damage occurring since the EMT would be strapped in place (not possible of moving) and the wire wouldn't really be exposed to the edges of the tubing since it still has to pass through the upper and lower wall plates. Thoughts?

Thanks,
Matt

 

[mopowr steve]

You may not need to provide additional protection for the cable since it’s “fished in” as the normal fastening of drywall and trim it’s already done therefore the danger of nails or screws are for the most part a mute point.

 

[infinity]

Look at 338.12(A)(1) which directs you to 250.50(B)(4). EMT is on the list as being OK for protecting SE cable from physical damage.

 

[Bahnsen]

Look at 338.12(A)(1) which directs you to 250.50(B)(4). EMT is on the list as being OK for protecting SE cable from physical damage.

Thanks infinity. I omitted an important detail in my original post that I should have mentioned. My meter socket location is being changed, and so my old main load center is now becoming a subpanel. The SER wire I am running and having questions about is from my new meter/main combo to my old main load center.

If I follow your original reference to article 338 for my particular situation, this is how I understand the "flow" of the code:

Chapter	NEC Article	Part	Reference Title	NEC Reference	Points to
3 - Wiring Methods and Materials	338 - Service Entrance Cables Type SE and USE	II - Installation	Uses Permitted	338.10 (B) (4)​	334 Part II [excluding 334.80]
3 - Wiring Methods and Materials	334 - Nonmetallic-Sheathed Cable: Types NM, NMC, and NMS	II - Installation	Through or Parallel to Framing Members	334.17​	300.4​
3 - Wiring Methods and Materials	300 - General Requirements For Wiring Methods And Materials	I - General Requirements	Protection Against Physical Damage	300.4 (D)​	​

When I finally land at 300.4 (D), here is the guidance that I was referencing in my original post:

...the cable or raceway shall be installed and supported so that the nearest outside surface of the cable or raceway is not less than 32 mm (11∕4 in.) from the nearest edge of the framing member or furring strips where nails or screws are likely to penetrate. Where this distance cannot be maintained, the cable or raceway shall be protected from penetration by nails or screws by a steel plate, sleeve, or equivalent at least 1.6 mm (1∕16 in.) thick.

Exception No. 1: Steel plates, sleeves, or the equivalent shall not be required to protect rigid metal conduit, intermediate metal conduit,
rigid nonmetallic conduit, or electrical metallic tubing.

Exception No. 2: For concealed work in finished buildings, or finished panels for prefabricated buildings where such supporting is impracticable,
it shall be permissible to fish the cables between access points.

Since I have already busted open the drywall between my wall studs, I'd like to do what I can to prevent future home owners from accidentally damaging the cable.

So then, if I use appropriately sized and supported EMT to sleeve the cable between the upper and lower wall plates, and I use bushings on each end of the EMT to ensure the sharp edges can't damage the cable, I'm not missing anything that NEC would require me to do, correct?

Thanks!
Matt

 

[LarryFine]

You can use the sleeve, but you don't have to. As long as you can secure the cable at least 1.5" away from the nearest stud, and protect the top- and bottom-plate penetrations with nail plates you're golden.

 

[infinity]

You can use the sleeve, but you don't have to. As long as you can secure the cable at least 1.5" away from the nearest stud, and protect the top- and bottom-plate penetrations with nail plates you're golden.

That's correct but as a practical matter how would you do that with a cable that is 1½" in diameter?

 

[wwhitney]

That's correct but as a practical matter how would you do that with a cable that is 1½" in diameter?

A plastic strap across the stud bay, with one wrap around the cable, at a couple different heights?

Cheers, Wayne

 

[LarryFine]

That's correct but as a practical matter how would you do that with a cable that is 1½" in diameter?

Flat 2x4 with a large staple or a 1- or 2-hole strap in a coupe of places.

 

[LarryFine]

A plastic strap across the stud bay, with one wrap around the cable, at a couple different heights?

Cheers, Wayne

Or that. Or anything that effectively functions as a large Colorado Jim.

Even a Mineralac strap on a spacer or a plumbing standoff could work.

 

[Dennis Alwon]

That is what I did. 2x4 flat across the studs mounted to one end and the cable strapped to it.

 

[LarryFine]

That is what I did. 2x4 flat across the studs mounted to one end and the cable strapped to it.

After all, isn't that what we usually do between the studs above a panel?

A couple of pics I found on the interwebs:

 

[Dennis Alwon]

After all, is't that what we usually do between the studs above a panel?

A couple of pics I found on the interwebs:

Yep That is what I used to do only with 2x4's not metal

 

[LarryFine]

Yep That is what I used to do only with 2x4's not metal

The one in the left pic is wood.

 

[Bahnsen]

Appreciate all the comments. What I (and also infinity) were pointing out above is that NEC requires (see 300.4 D reference above) protection for a cable if it is closer than 1.25 inches from the face of the 2x4. The cable I am using is 1.5" diameter. Given the width of a 2x4 being 3.5 inches, you can quickly see that if the cable is run down the center of the stud that there is only 1" of clearance on each side of the cable, thus requiring protection per the code.

I get that some local practices might overlook this, but it nevertheless is not NEC-compliant.

My question to the group is if anyone can tell me if I am overlooking anything in my approach above (repeated below here):

So then, if I use appropriately sized and supported EMT to sleeve the cable between the upper and lower wall plates, and I use bushings on each end of the EMT to ensure the sharp edges can't damage the cable, I'm not missing anything that NEC would require me to do, correct?

 

[infinity]

The idea is to support the cable so that it is 1.25" or farther from the stud edge like in Larry's photo. Or use EMT as you've proposed.

 

[retirede]

Appreciate all the comments. What I (and also infinity) were pointing out above is that NEC requires (see 300.4 D reference above) protection for a cable if it is closer than 1.25 inches from the face of the 2x4. The cable I am using is 1.5" diameter. Given the width of a 2x4 being 3.5 inches, you can quickly see that if the cable is run down the center of the stud that there is only 1" of clearance on each side of the cable, thus requiring protection per the code.

I get that some local practices might overlook this, but it nevertheless is not NEC-compliant.

My question to the group is if anyone can tell me if I am overlooking anything in my approach above (repeated below here):

Appreciate all the comments. What I (and also infinity) were pointing out above is that NEC requires (see 300.4 D reference above) protection for a cable if it is closer than 1.25 inches from the face of the 2x4. The cable I am using is 1.5" diameter. Given the width of a 2x4 being 3.5 inches, you can quickly see that if the cable is run down the center of the stud that there is only 1" of clearance on each side of the cable, thus requiring protection per the code.

I get that some local practices might overlook this, but it nevertheless is not NEC-compliant.

My question to the group is if anyone can tell me if I am overlooking anything in my approach above (repeated below here):

The 1-1/4” from the front face applies if the cable is within 1-1/2” of the stud laterally. Anchor it in the cavity away from the stud and it can be touching the wallboard.

See posts 5 & 8.

 

[Little Bill]

Sorry to have to do this but the Forum rules won't allow us to assist, even Engineers, with DIY projects.
I think sufficient info has been given. With that said......

I am closing this thread in accordance with forum rules. This forum is intended for use by electricians and electrical contractors, inspectors, engineers, and vendors with their job-related duties. We are not allowed to provide how-to advice to persons who are not employed in this industry, or persons who do not perform electrical installation or maintenance as part of their jobs. Engineers are welcome to participate, but only if their questions do not involve attempts to perform their own electrical installation, troubleshooting, or maintenance work.

If I have misread the situation, if for example you have an electrical contractor on board to perform the installation work, then send me a PM to explain the circumstances.