Many of the homes in this area use a Polyisocyanurate Insulation on the outer block walls and then faced with ½" furring strips for dry wall. This insulation board is typically 5/8" and has an aluminum facer on both sides.

The typical wiring is NM down the walls and secured with stand-offs to 4" sqaure boxes. The NM is kept 1¼" from the furring strips but will be right up against the dry wall.

Any concerns in regard to this or is the possible hazard no more than it is with NM run along metal studding?

We only have to be nervous until July ;-)

I have never liked this method. The drywall guy may be able to hit the furring but the homeowner will just start poking holes until he hits something. A cheap stud finder might actually be happy "finding" that wire.

Bryan,

In 300.4(D), I think the 1-1/4" space is from the outside edge of the framing member, but actually on the framing member, as shown on exhibit 300.3. Therefore, 300.4(D) would not apply for the 1/2" furring strip. I think this furring issue is a lifesafety issue for the homeowners. Couldn't the area between the furring strips be considered "shallow grooves" as in 300.4(E)? I think that if there is less than 1-1/4 in. between the outside surface of the cable and the outside edge of the gypsum board, then some protection is needed.

I just read the new 300.5 and they really didn't fix anything. If the wire is 1¼ off to the side of the furring strip, without protection, it is still OK. They show a picture of unprotected RX running horizontally between furring strips in the analysis oof changes book. It looks like hanging them on a stacker will still be legal. I guess NFPA is waiting for the body count.

Bryan, are your concerns with the nm between the furring strips but in contact with the drywall? If there are grooves notched in the insulation for the nm than I would agree with Vince on using 300.4 (e).Gfretwell did you mean 300.4? I have seen application where they have run SER feeders on an outside wall of an apartment building and the SER was 1 1/4 away from all framing members but ended up touching the drywall in between the studs.I made them fur out the walls to get 1 1/4 inch space between the drywall and the cable, but that was a stretch using ahj as the code doesn't really address this issue.

Yes, I am concerned with the fact that the cable is in direct contact with the drywall and a large sheet of aluminum foil. I know a homeowner has to show some care when driving nails or screws into an outer wall, but it just seems to me the hazard is greater with the conductive covering on the insulation board.

I'm just imagining the entire 4' x 8' board energizing...

You know, going back to the code wording...Greg is right in that they really haven't fixed anything. When I saw the change for the first time in our ANALYSIS book from the seminar, I thought everything was great, but taking a closer look, it isn't.

Look at the illustration. Where the cable is parallel to the furring strip it is protected. But where the cable passes behind the furring strip (perpendicular) it is not nail plated 1 1/4" on either side. So, the logic here is flawed. Additionally, look at where the cable goes over the top of the furring strips.

Missing some nail plates ?? You think ?

We should do a proposal to add the words "and perpendicular" to the article. If you feel that this is valid, please comment.

Bridgeport Fittings recently received UL listing for Steel Protector Strips that will provide protection of NM and low voltage cables in homes built with block wall and furring strips. They will be available mid-March.

These strips are the same thickness as steel plates ('kicker' plates) used on wood studs and furring strips as required by Article 300 and come in 3-foot lengths. Steel Protector Strips were displayed at IAEI metting in Cocoa Beach in October 2005.

While my home was being built in Port Saint Lucie I noticed that the NM cable could, and was, attached anywhere along the block walls. In some outlets two cables were stacked and attached to wall. I had concern that once wallboard was installed all cables are hidden and could be penetrated by nail or screw when hanging pictures, mirrors, etc. My concern wasn't for myself but for other homeowners who would have no idea if cable, or how shallow behind, cables are attached to wall.

If anyone would like further information regarding these Steel Protector Strips please contact me at kenk@bptfittings.com.

(Disclosure: I am the Engineering Manager at Bridgeport Fittings, a home owner in Port Saint Lucie, and a member in IAEI chapter 90 since 1985)

Thanks for that information Ken.

I look forward to seeing some more details on this product. Do you guys have a brochure or webpage on it yet?