ELECTRICAL CONDUIT BELOW METAL DECKS

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edfred

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Kansas
In the last two years Buckley Roofing has paid out over $40,000.00 due to our roofing screws screwing into conduits installed above the bar joists in the fluts of the deck. With 98% of all roofing systems requiring screws for thier attachment this issue must be addressed. We recently had a claim where the short occured over a year after we had completed the project. There is a real possibility that someone will be killed before this practice of installing the conduits in the fluts is stopped. The requirment for the roofing industry is that the screws must penatrate the deck a min. of 3/4" and many times it will be 2" to 3". What can be done to stop this practice. I recently had an electrician tell my foreman that he should not screw in this area because he had run his conduits there. I didn't know he could rewite the spec book on how I was to install my roof all for his convience. Can any one comment on this subject? Thank you.
 
Re: ELECTRICAL CONDUIT BELOW METAL DECKS

The only way for your company to address this would be at pre-construction meetings or a disclaimer in your contract saying you will not be liable for damages arising from such incidents.
 
Re: ELECTRICAL CONDUIT BELOW METAL DECKS

What about citing a violation of 300.4(B)(2) for this application if the conduit is EMT?
(B) Nonmetallic-Sheathed Cables and Electrical Nonmetallic Tubing Through Metal Framing Members.
(1) Nonmetallic-Sheathed Cable. In both exposed and concealed locations where nonmetallic-sheathed cables pass through either factory or field punched, cut, or drilled slots or holes in metal members, the cable shall be protected by listed bushings or listed grommets covering all metal edges that are securely fastened in the opening prior to installation of the cable.
(2) Nonmetallic-Sheathed Cable and Electrical Nonmetallic Tubing. Where nails or screws are likely to penetrate nonmetallic-sheathed cable or electrical nonmetallic tubing, a steel sleeve, steel plate, or steel clip not less than 1.6 mm (1/16 in.) in thickness shall be used to protect the cable or tubing.
Don
 
Re: ELECTRICAL CONDUIT BELOW METAL DECKS

edfred, I am guilty of doing this, and I can understand your position.

I think if you go into the bidding process with some documentation of past problems along with the code article that Don shows you could make a good argument for something to be put in the job specs. that would both prohibit putting electrical in the "flutes" but it should leave the electrician the option of going into the flutes if proper protection is installed because some times it will be an I beam not a truss and going under may not be an option and if they do make them financially responsible.

Many of the job specs. we get now forbid us from supporting to the deck itself so I do not think an additional requirement to stay 1 1/4" down from the lowest part of the decking would be a big deal I picked 1 1/4" as it is a measurement we already use for something similar.

If you get this into the spec be sure to bring it up at job meetings so the electrical contractor is aware of this (he should read his spec but help each other out).

If the electrician has a bad attitude with you cut him some slack it is probably because he shredded his hands on your sharp screws sticking thru the deck 2" to 12" :D
 
Re: ELECTRICAL CONDUIT BELOW METAL DECKS

I fixed this same problem at a Sears fasion center on 5 AHU and a feeder to a 3ph. 480v. transformer, among some smaller branch circut conduits.
The roofing contractor was charged by Sears for the repairs.
Don. I agree with you on Code, but in our situation, the conduits were existing(we didn't install them). This was a replacement roof. Sears' view was that the roofing contractor should have looked at what they could have potentially hit, took measurements, and marked where any potential obsticles were. Sears won.

Edfred, on your side, I think that conduits shouldn't be run in fluts. I don't think that we'll see this practice stopped.
On the electrician's side, if he had held his conduits down 1 1/4in. you would probably still have hit them with 2-4in.screws.
If the requirement is 3/4in. penetration minimum, is there a need to go 3,4,5 inches more? What would be and acceptable distance to allow for the screws? What precautions, if any, does your company take now to prevent this? Mine won't run in the fluts, but what about the others?? Todd
 
Re: ELECTRICAL CONDUIT BELOW METAL DECKS

The roofing guy may have better info but I think what happens around here is they use different thickness' of insulation to make the water run to the drains (along with roof pitch) so they have one length of screw sometimes 3/4" sticks through but some places I have seen up to 6" sticking through.

The effect of requiring 1 1/4" would mean you would have to go under the top cord of the truss which would mean by the time you put a support hanging down on the top cord you would be down at least a 2" or 3" unless you offset back up to the deck after each truss
 
Re: ELECTRICAL CONDUIT BELOW METAL DECKS

Originally posted by edfred:
In the last two years Buckley Roofing has paid out over $40,000.00 due to our roofing screws screwing into conduits installed above the bar joists in the fluts of the deck. With 98% of all roofing systems requiring screws for thier attachment this issue must be addressed. We recently had a claim where the short occured over a year after we had completed the project. There is a real possibility that someone will be killed before this practice of installing the conduits in the fluts is stopped. The requirment for the roofing industry is that the screws must penatrate the deck a min. of 3/4" and many times it will be 2" to 3". What can be done to stop this practice. I recently had an electrician tell my foreman that he should not screw in this area because he had run his conduits there. I didn't know he could rewite the spec book on how I was to install my roof all for his convience. Can any one comment on this subject? Thank you.
Part of the problem may be a regulatory one. Some AHJs have taken the position that bar joist are not listed to support weight in any way except on top. What led those jurisdictions that take that position to that dubious conclusion was never clear to me. I had an entire warehouse conversion turned down because we had supported EMT up to an 1&1/4" trade size from the bottom cord of the truss. They were supported with stand off straps fastened by long machine screws and large fender washers resting on the top edge of the two opposing angle irons that made up the bottom cord of each truss. Once that position was taken we ran most of the remaining circuits in MC cable pulled through the little valleys in the metal decking that I think you are referring to. That was the only way to get out of the job with a financially whole skin. We speed lettered the roofers that they were responsible to use the correct screw lengths. The GC hated it but that is what happens when AHJs make up new rules as they go along. Three months later the AHJ was overturned by the appeals board on an identical order issued on the ground floor of an eighteen story building. That job being so much larger the electrical contractor found the cost of the appeal and the inspectors enmity worthwhile and he won.
--
Tom
 
Re: ELECTRICAL CONDUIT BELOW METAL DECKS

Don,
The code article you cited was for ENT not EMT.

Donnie

[ March 13, 2003, 10:08 PM: Message edited by: txsparky ]
 
Re: ELECTRICAL CONDUIT BELOW METAL DECKS

Thanks for the input. IT is very difficult to keep track of the exact location of the conduits. We may have 5/8" gyp on the deck, tapered insulation in 3 to 4 layers and a cover board all screwed down with several lengths of fasteners.
It would be in everyone's best interest that a code be made to not allow any conduits within 6" of the deck. The projet would become safer, the electrician's contact just became a little larger and the employee just got a few more hours of work. Codes protect everyone, in this case we all need to support such a code requirment. Anyone interested in helping request such a code from the NEC?

Ed Fred
 
Re: ELECTRICAL CONDUIT BELOW METAL DECKS

Donnie,
You are very correct, I read the section too fast. Looks like no one else read the section as you are the first person to catch my error.

Ed,
As far as a code change, it will have to wait until the 208 code. The deadline for proposals for the 2005 code was early last November.

Don
 
Re: ELECTRICAL CONDUIT BELOW METAL DECKS

Are these super rush jobs, I have never been on a job where the electricians were running conduit on top of bar joists before the deck was put on. Could it be that you are putting the deck on with a few screws then coming back to add more screws later, if this is the case you shoiuld let other trades know what your doing sounds like bad communication at the jobsite.
 
Re: ELECTRICAL CONDUIT BELOW METAL DECKS

sjaniga, Many times there is a long period between when the corrugated decking goes down by the steelworkers which in my area is welded to the truss, and the time when the roofers screw the insulation down on the decking.

During this time you might run EMTs through the spaces on top of the truss, and when the roofers come and screw down the insulation is when you can get "screwed"
 
Re: ELECTRICAL CONDUIT BELOW METAL DECKS

I have a good one!!!2 years ago in a nudist colony we did there was a Tiki bar.Good sized one 1,500 sq. ft. Anyway the roof was 5/4 T&G,with track lighting,ceiling fans,
receptacles, L.V etc.All of our MC and EMT was behind the T&G ,Over the T&G was 3 in. insulated sheathing.So 300.4 d goes away right ???
NOT !!! with screws required to secure the sheathing to the sub roof there were 4 screws through our wiring.Contractor had to remove sheathing pay to repair and reinstall sheathing. :eek:
 
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