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Old 12-04-2009, 01:18 AM   #1
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Metal Plate for Stud's Face to Protect Cable


My understanding of the NEC is that cable has to be recessed at least 1-1/4” from the edge of studs or a metal plate should be used on the face of the stud to protect the cable.

Does BX (AC-90) also require this additional metal plate? I assume so, but I wonder of the metal cladding on the cable is sufficient protection.

Also, I know that a variety of nail plates are manufactured for this purpose for use on wood studs for example, but does the NEC have specific requirement parameters for the type of plate: thickness, type of metal, etc?

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Old 12-04-2009, 05:51 AM   #2
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Metal Plate for Stud's Face to Protect Cable


From the 2008 edition of the NEC:

Quote:
300.4 Protection Against Physical Damage ...

(A) Cables and Raceways Through Wood Members.

(1) Bored Holes.
In both exposed and concealed locations, where a cable- or raceway-type wiring method is installed through bored holes in joists, rafters, or wood members, holes shall be bored so that the edge of the hole is not less than 32 mm (1¼ in.) from the nearest edge of the wood member. Where this distance cannot be maintained, the cable or raceway shall be protected from penetration by screws or nails by a steel plate(s) or bushing(s), at least 1.6 mm (1/16 in.) thick, and of appropriate length and width installed to cover the area of the wiring.

Exception No. 1: Steel plates shall not be required to protect rigid metal conduit, intermediate metal conduit, rigid non-metallic conduit, or electrical metallic tubing.

Exception No. 2: A listed and marked steel plate less than 1.6 mm (1/16 in.) thick that provides equal or better protection against nail or screw penetration shall be permitted.
There is no provision to exempt type AC cable ("bx") from the nail-plate protection requirements.

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Old 12-04-2009, 09:49 AM   #3
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Metal Plate for Stud's Face to Protect Cable


Big box stores carry the Simpson nail plates
That's all I've used
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Old 12-04-2009, 09:54 AM   #4
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Metal Plate for Stud's Face to Protect Cable


You may find larger plates in the plumbing aisle.
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Old 12-04-2009, 11:07 AM   #5
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Metal Plate for Stud's Face to Protect Cable


I went to Lowes (usually go to Home Depot but they were closed) and they only had a plate measuring 2.5" x 1.5", not wide enough to cover the wide face of a 2x4 stud (3.5" actual width). Also, the plates look to be made for Romex as they have spikes that enter the wood and they are narrowly space for Romex to fit under, I doubt BX would fit.

I need a plate 3.5" long and not much wider than 1"-1.5".

What size are the plumbing plates?
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Old 12-04-2009, 11:12 AM   #6
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Metal Plate for Stud's Face to Protect Cable


I have seen plates about 6" long for larger pipes.

The plate can be wider.
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Old 12-04-2009, 12:11 PM   #7
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Metal Plate for Stud's Face to Protect Cable


Quote:
Originally Posted by Lovegasoline View Post
not wide enough to cover the wide face of a 2x4 stud (3.5" actual width). Also, the plates look to be made for Romex as they have spikes that enter the wood and they are narrowly space for Romex to fit under, I doubt BX would fit.
can you expand on that a bit?


this is a nail plate:


the cable doe not go under the cleats. The plate is placed longitudinally along the stud and the cleats are only to hold the plate into the stud.

Since a standard 2X4 is 1 1/2" wide, the 1 1/2" wide plate would be fine for a 2X4.

Now, if you need to protect the wide side of the 2X4, you can place 2 of those side by side or hunt for a wider plate.
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Old 12-04-2009, 12:14 PM   #8
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Metal Plate for Stud's Face to Protect Cable


Quote:
Originally Posted by Lovegasoline View Post
I went to Lowes (usually go to Home Depot but they were closed) and they only had a plate measuring 2.5" x 1.5", not wide enough to cover the wide face of a 2x4 stud (3.5" actual width). Also, the plates look to be made for Romex as they have spikes that enter the wood and they are narrowly space for Romex to fit under, I doubt BX would fit.

I need a plate 3.5" long and not much wider than 1"-1.5".

What size are the plumbing plates?
Why are you using the wide side of the 2x4?
The nail plate you have is pretty standard.
You drill the hole into the center of the stud, then nail the nail plate on the front of the stud, centered over the hole you drilled.
the plate is not used to pass romex or any other wiring methed under them.
The prongs are made to nail inito the face of the wood.
I have never seen any wider than 1.5 inches.
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Old 12-04-2009, 12:29 PM   #9
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Metal Plate for Stud's Face to Protect Cable


It sounds like the wall was built with the studs turned 90 degrees from normal. The Op now needs to protect a cable across a 3 1/2" face and is trying to use the length of the plate across the width. This means the teeth are around the cable or too small to allow the cable between the teeth.

I might just use some old box sides or a 1900 blank.
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Old 12-04-2009, 12:55 PM   #10
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Metal Plate for Stud's Face to Protect Cable


Quote:
Originally Posted by Jim Port View Post
It sounds like the wall was built with the studs turned 90 degrees from normal. The Op now needs to protect a cable across a 3 1/2" face and is trying to use the length of the plate across the width. This means the teeth are around the cable or too small to allow the cable between the teeth.

I might just use some old box sides or a 1900 blank.


Jim, you've described the situation precisely. Also, the plates' length is too short to span the full 3.5" wide stud, and the prongs are in the way.

The 2x4’s wide side faces the room. I’ve used a router to make a 5/8” groove across the face of the 2x4 and that is where the 12/2 BX (cable outside diameter = 1/2”) is sitting.

Trying to minimize the mess and repair work, I’ve made as small a hole in the plaster/lathing as possible…so I can’t use a huge wide plate. Generally the hole is 10" long x 3" tall, but I tired only to remove one section of lathing strip and ran the router there on the exposed wood stud. I left the other lathing strips intact so I can screw sheetrock plugs in.

The metal protection plates' prongs will likely interfere with the BX cable, they aren’t spaced wide enough apart (never having worked with Romex, I had incorrectly assumed that Romex would fit under the metal plate’s prongs)



"I might just use some old box sides or a 1900 blank". Can you elaborate on that, not sure what exactly you are suggesting?

I really need to get this done ASAP. Is there a product/solution that would work?


Last edited by Lovegasoline; 12-04-2009 at 01:00 PM.
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Old 12-04-2009, 01:11 PM   #11
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Metal Plate for Stud's Face to Protect Cable


Quote:
"I might just use some old box sides or a 1900 blank". Can you elaborate on that, not sure what exactly you are suggesting?

I really need to get this done ASAP. Is there a product/solution that would work?

I think you could use the blanks (the ones intended for hex or square boxes), as they are certainly at least as thick as the nail plates are.
You would just need to drill two holes to attach the plate to the stud.
Just make sure you drill these holes so that they don't interfere with the cable passing beneath

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Old 12-04-2009, 01:11 PM   #12
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Metal Plate for Stud's Face to Protect Cable


so you use 3 of the plates side by side. I don't see what the problem is. The prongs on the nailers are about 3" apart so there is plenty of room for the cable between them.

or keb2k's suggestion is a great one as well.

you are trying to put the nail plates on the wrong direction. They are not made to run the NM the length of the nail plate, the bore hole or cut out runs perpendicular to the plate.



If you cannot fit a proper plate in what you have cut out, you are simply going to have to cut out enough so you can install a plate. SImple as that.

Last edited by nap; 12-04-2009 at 01:14 PM.
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Old 12-04-2009, 01:14 PM   #13
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Metal Plate for Stud's Face to Protect Cable


I've got some on my truck that are 6" long, but all of them are 1.5" wide.
Check the plumbing section.
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Old 12-04-2009, 01:21 PM   #14
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Metal Plate for Stud's Face to Protect Cable


Quote:
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I've got some on my truck that are 6" long, but all of them are 1.5" wide.
Check the plumbing section.
I think the problem is lovesgasoline has cut a hole not large enough to place the plate on in the proper orientation and is trying to put it sideways. That is why the prongs of the plate are a problem for him. He just needs to do what he needs to do to install a proper plate and fix as needed.
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Old 12-04-2009, 01:28 PM   #15
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Metal Plate for Stud's Face to Protect Cable


Buy a strip of metal, 1 or 1.25" wide, 1/16" thick, cut it to the proper length, and use it to cover the groove you cut. Set it in place, add some quick setting mud to hold it in place, and you are done.

You can find these at the home stores in 3 or 4 ft lengths.

FWIW, AC (bx) is treated just as like Romex as far as required physical protection needs.

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