ECN Forum Forums General Topics of the Trade General Discussion Area romex, used on a solid block wall ?

they should, ask for an emt-nm conn.

The adapters pictured are readily available. Home Depot even has them.
On bloc wall jobs I have used NM straps screwed into the block at about 2-3" from the furring strip. If you punch out the block and nail a metal box with a side bracket to the furring strip the cable can be fed into the box. I have done several jobs this way and never had a problem passing.
BTW,
Where can the requirement for 1 1/4" to finished surface be found?

I know this doesn't help the queries re whether this is a violation of the NEC, but it's a situation that crops up regularly in British wiring where brick and block walls are very common.

The common approach is to run the NM on the block wall and "protect" it with galvanized steel channeling before the drywall is installed.

I put protect in quotes, because it doesn't really offer that much protection against a nail or drill.

I didn't know you could run NM cable through conduit?

I thought conduit was only listed for individual wires.

thanks pauluk, the gal steel channel sounds like a great idea to protect the cables from physical damage.

SvenNYC,
check note 9 to Chap 9 Tables (pg 70-617 2002) ,i believe it alludes to nm and similar wiring, listings aside of course....

Paul brings a point of interest,
(insignificant to this thread but of worthy mention) in that a 'channel' may not encapsulate 360 deg's as a conduit....so derating/conduit fill flys out the window...

[This message has been edited by sparky (edited 11-21-2002).]

Around here we wire plenty of concrete block homes.

We use what is called a romex stand off strap. It is a plastic device that is nailed alongside of a furring strip. It has grooves that the romex slides into and it keeps the space from the furring strip at 1 1/4".

We use plastic metal bracket boxes nailed to the furring strips for installing devices.

Locate the box in the hollow of the block and knock a hole in the wall. Use spray foam around the box after the job is done to seal up any air leaks. The spray foam also helps hold the box in the wall too.

For horizontal runs of nm notch the furring strips and run the wire through. Use nail plates over the romex to protect the wire from being hit by a drywall nail.

All of this pases local inspections and the cost is very reasonable both to the electrical contractor and customer.

Two man average crew can do a 1400sf house in about 2-3 days. Down here our houses don't have basements though.

fla sparkey, can you give more details about the romex on block walls? are could someone post a photo of the procedure?

Sorry mj, I don't have a digital camera yet. Kind of hope to maybe get one for Xmas this year.

Because we wire a lot of block houses the local supply houses carry the plastic standoff straps I described. The metal nail plates are a standard item as well.

You might try Lowe's or the big orange box for these items and the boxes as well.

Installing an electrical system this way is fairly simple.

If you have a specific question or two I will try to answer them for you.

mj,
Are these solid block walls or are they the kind that I am use to,16in with a center web and open cells on both sides of the web,except around openings when they are filled with rebar and concrete?
Down here in the Sunshine state there are a lot of block homes that use open cell blocks that are suitable for running NM in the open vertical cells.This will protect the cable from just below the lentil or header block down to the slab.
For cables behind sheet rock we are required to keep the NM 1.25 inches away from any framing member and that includes the furring.There is a stand off clip that screws into the furring and keeps the wire offset the proper distance.We also have used cut nails and wire ties for this purpose.Plastic boxes are punched into the open cells in the block and secured with furring and cut nails.
Once the rough in is inspected then the cells are filled wth foam for better insulating properties.This will not prevent the home owner from driving a long nail or screw into the cable unless the cable is in the cell.
Chris