Run MC cable/Romex Cable behind baseboard?

[zemingduan]

Hi guys does NEC allow you to run MC cable/Romex Cable behind the baseboard? I know NEC require the MC, Romex cable to be protected from the physical damage. And I know It is not recommended and is not a good idea to run them behind the baseboard since you don't want the nails damage the cables.

However, for the old houses and historical buildings with solid wall, there are many situations that the architect asks to install the receptacle outlets in the baseboard and conceal the wiring inside the baseboard. Seems many architects don't like the look of surface mounted raceway for many historical buildings.

I found NEC 300.4 Protection Against Physical Damage

(F) Cables and Raceways Installed in Shallow Grooves
Cable- or raceway-type wiring methods installed in a groove, to be covered by wallboard, siding, paneling, carpeting, or similar finish, shall be protected by 1.6 mm (1/16 in.) thick steel plate, sleeve, or equivalent or by not less than 32-mm (11/4-in.) free space for the full length of the groove in which the cable or raceway is installed.

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: 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.

It seems that NEC allow you to install behind the baseboard as long as you leave 1-1/4" free space. I am also thinking to ask rigid metal conduit behind the baseboard for the wiring. Is it feasible? Not sure in most cases if you can have enough space for the rigid metal conduit behind the baseboard.

Thanks,

 

[Rick 0920]

Interesting question. Are you referring to a new install or remodel? If a new install, my question would be why do you want to do that? A lot of houses in Florida are built with cinder block and furring strips. If a customer wants you to add a receptacle it would be difficult to drop it from the attic and fish it down through such a thin space. I have popped the baseboards off, notched a little sheetrock, and fished a cable up 13" to a receptacle and ran it along the slab (since the sheetrock is usually installed about 1/2" to 3/4" above the slab.) You have to measure to make sure where your hollow cells are in the block because you will have to bust out the block for your new box. The Code compliant way would then be to use a nail plate(s) all along the floor line to maintain your 1 1/4" clearance. But if you're the one putting the baseboard back up, is that really necessary? If you drive a nail into a wire that you ran 5 minutes ago, you might want to rethink your career choice! Now something I just now thought of........If we run NM cable directly on the slab behind the baseboard, is this a damp or wet location because concrete is porous? Then again, hasn't the NM cable been secured to porous cinder block for over 50 years in new installations? Seems like a great opportunity for the cable industry to dig their claws into the CMP's to require UF cable on all exterior walls of concrete or block! LOL

 

[Fred B]

334.12(A)(9) Prohibits NMC and NM from being embedded in poured concrete.
334.12(B)(3) only prohibit NM in hollow of Cinderblock walls but would allow NMC. (Never seen NMC though)

If you able to secure the NM on the block or concrete wall as well as provide protection or 1-1/4" depth, on the surface of interior is allowed. Biggest issue is the securing as no easy means to do that for the typical 12 or 14 cable. Arlington makes a strap listed for use with NM but not sure it is usable in shallow wall.

 

[Rick 0920]

334.12(A)(9) Prohibits NMC and NM from being embedded in poured concrete.
334.12(B)(3) only prohibit NM in hollow of Cinderblock walls but would allow NMC. (Never seen NMC though)

If you able to secure the NM on the block or concrete wall as well as provide protection or 1-1/4" depth, on the surface of interior is allowed. Biggest issue is the securing as no easy means to do that for the typical 12 or 14 cable. Arlington makes a strap listed for use with NM but not sure it is usable in shallow wall.

My inspectors would allow us to use a small piece of the NM jacket, fold it over the cable, and use a case hard nail (cut nail) to secure the cable to the block wall. This allowed us to maintain our 1 1/4" distance from the furring strips.