Rib of Metal Decking and Electrical

Status
Not open for further replies.
Dean83169

Dean83169

Senior Member
Has anyone heard of if its against NEC or Building code to run cables above the metal joists but below the roof decking in the rib. We have done this for years but an inspector in CT has said its against code because if they drill a screw from the rrof they may hit the wire. Well if thats the case we should put nail plates on all studs because they MAY use a 4" sheetrock screw. Somenoe else said its because of the crush factor of the roof, but if that rib crushes I think you have more problems then a cable being POSSIBLY destroyed. Does anyone know if this is a building code or heard of such a thing. Is it that the new inspectors have nothing else to gripe about so they have to find something?
 
This sounds like one of those it's-done-all-the-time things that you'd have to ask the inspector to cite in the rule book.
 
I have never heard that....then again, have you ever seen the length of the screws those guys use? I mean they are obscenely long ...worse than cabinets guys screws.


I would ask him to cite an article that prohibits it.

"IF" is a very vague term .....should all homes be built of steel reinforced poured concrete so that IF a plane hits it, the people in the house won't suffer any loses?

When does it end?

"IF" w/o any substantiation, IMHO, is opinion and not "code".
 
John Arendt said:
Celtic:
The only thing that comes to mind is the 1-1/4" rule.
John
Click to expand...

I said to myself out loud:
What 1 1/4" rule with pipe??

Then I re-read the OP...opps
 
I'm not sure that I am visualizing correctly how the cable is being installed, but it sounds like 300.4(D) might apply?
 
Regardless of the screws they use, I as I am sure others have, seen these screws come through the decking and directly into a pipe that is through that rib. The height from the bottom of the upper rib to the top of the joist is about 3 inches. Now take into consideration that the roof material is almost 5 to 6 inches thick. So what I am looking for now is an inspector who can quote to me such a code from this forum.

Years upon Years of doing this and now in this city; its a problem. Why doesnt the inspector say to himself:

"Self, I need to talk to the roofing guy to make sure he doesnt use those 10" drill screws when he only needs the 6" screws"

I am so tired of inspectors making their own codes and whats ok in this town isnt in that town,,:mad: ,,,ok note to my self "BREATHE",,,,,,,,,:confused: ,,
 
Last edited:
The 2008 code will address this issue. The following is the result of CMP3's action on comment 3-10.
(E) Cables and Raceways Installed Under Roof Decking. A cable or raceway type wring method, installed in exposed or concealed locations under metal-corrugated sheet roof decking, shall be installed and supported so the nearest outside surface of the cable or raceway is not less than 1 ? in. from the nearest surface of the roof decking.
FPN: Roof decking material is often repaired or replaced after the initial raceway or cabling and roofing installion may be penetrated by the screws or other mechanical devices designed to provide “hold down” strength of the water-proof membrane or roof insulating material.
Exception: Rigid metal conduit and intermediate metal conduit shall not be required to comply with 300.4(E).
Click to expand...
[FONT=&quot]
Don[/FONT][FONT=&quot]
[/FONT]
 
Thanks thats what I am talking about, Will this conflict with building codes don?
BTW what is CMP and 3-10 in your post don?
 
Last edited:
Dean,
CMP is Code Making Panel. This is the group of people that review and act on on code change proposals and comments. The results of the CMPs action is voted on at the NFPA membership meeting and if passed becomes the new NEC. 3-10 is comment 3-10 in the Report on Comments for the 2008 NEC. The ROC will be published online here in the near future. The ROP (Report on Proposals) is there now.
Don
 
Eddie I have too myself and been contracted a few times to fix this very thing. But we have done this for years and its no different then the 1 1/4" rule for wood studs. We can only assume the rocker will install 3/4" screws if we are scared of the roof guy then we should be scared of the rocker too of installing 2" screws or the cabinet guy or the homeowner installing pictures on the wall. If that were the case we should install nail plates on all studs. It common practice to use what you need for material but not over do it. I do not think the roofers need to use such long screws nor do I feel that when a portion of roof deck needs to be replaced, that the unqualified non english speaking person, start without looking to see whats down below or to set his blade to the proper depth.
 
Dean,
As far as the screw length, many roofs used tapered insulation to provided high and low points for drainage. The installer will use the same length screw all the time even though the build up thickness may vary 2 to 3".
Don
 
I did an outdoor tiki bar at a nudist colony here (caliente) that had 5/4 t + g above the trusses and 3 in insulated sheathing on top covered with 3D shingles.The sheather's hit our emt and MC that was wired from above the T+G in 4 places.Luckily it was caught before the shingles were installed.They had to remove the sheathing so we could do the repairs and reinstall it so they could shingle the roof.

A guy I was doing it with decided to do a continuity check before the final roof was installed and a good thing he did.Cost the owners a bundle. But then again is you saw the millions of $$$ of rv`s that came there for the opening the cost was just a tip to us.

Want to see the place.

http://www.calienteresort.com/home/about.htm

On a side note I saw the most horrible sights there.:) Why is it that old rich people feel the need to run around in B Day suits ????
 
Status
Not open for further replies.
Top