Romex and cement block wall

Status
Not open for further replies.
M

mudcat555

Member
Location
Mentor, Ohio (25 miles east of Cleveland)
Occupation
Retired Electrician IBEW Local 38
The walls are cement block with 3/4 furring strips to which 1/2 inch drywall has been mounted. Can romex be run in the vertical channels behind the drywall as long as I don't penetrate thru the cement block or do I have to use mc cable. The walls are dry. Any code reference?
 
This would seem to be a "concealed" location as allowed by 334.10(A)(1), (B)(1), and (C)(1). I think if you had to go behind a furring strip you would need a nailer plate at that point.

Not sure how you would meet the requirements of 334.30 though.

Keep in mind there are restrictions on what kind of buildings can use NM at all.

Just how do you plan to mount boxes in that space though?
 
The first person that hangs a picture with a sheet rock anchor and screw will most likely find your wire behind the rock. That would be my luck. I'm designing a safe room into a home for us right now. I'm interested in any advice or fancy tricks anyone here has to offer on this. I figured we'd just furr the walls out with 2x4's laying flat ways.
 
This is a residential house. Where the boxes are mounted, they punched out the block wall in the block hollows. They ran ac cable. I am doing some remodeling for them and I would rather replace the boxes with plastic boxes and use romex.
 
You can run the NM vertically, horizontally, or diagonally. You can run it on the face of the block or make a hole and run it down the core. If you cross a furring strip, cut out a 1/2" channel and cover it with a nailing protector strip. If you run vertically, stay 1.25" away from the furring. There are various support devices for the NM cable that attach to the furring. You can also support it away from the furring with various straps or tape. I've used metallic duct tape successfully (passed inspection) but the concrete has to be dust-free for it to stick well. You are not required to protect the NM as long as you are 1.25" away from the furring which is the assumed location for drywall nails.
 
Coppersmith said:
You can run the NM vertically, horizontally, or diagonally. You can run it on the face of the block or make a hole and run it down the core. If you cross a furring strip, cut out a 1/2" channel and cover it with a nailing protector strip. If you run vertically, stay 1.25" away from the furring. There are various support devices for the NM cable that attach to the furring. You can also support it away from the furring with various straps or tape. I've used metallic duct tape successfully (passed inspection) but the concrete has to be dust-free for it to stick well. You are not required to protect the NM as long as you are 1.25" away from the furring which is the assumed location for drywall nails.
Click to expand...
Tape is not one of the means the code allows for securing and supporting NM. Just because the inspector allowed it (which is not within his authority) does not make it code compliant.
 
petersonra said:
Not going to work where you only have three quarters of an inch
Click to expand...
The metal is fairly easy to bend, so you can reduce the offset by making a new bend through the hole in the middle of the transverse leg.
Then flatten the short leg that has two holes.

Cheers, Wayne
 
mudcat555 said:
This is a residential house. Where the boxes are mounted, they punched out the block wall in the block hollows. They ran ac cable. I am doing some remodeling for them and I would rather replace the boxes with plastic boxes and use romex.
Click to expand...
Punch a hole in same hollow column and fish the cable down to the box, or drop it from top if that is accessible.
 
Status
Not open for further replies.
Top