# 2008 Nec 300.4(e)



## JohnJ0906

This is a new addition to the NEC for '08. When installing cable or conduit under a roof deck, it must be installed and supported 1 ½" from the decking. 

I just saw a perfect illustration of the need for this. If the conduit had been secured, I'm sure the screw would have pierced the EMT. As it was, it pushed it down.


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## Chris Kennedy

(E) Cables and Raceways Installed Under Roof Decking. A cable- or raceway-type wiring 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 38 mm (1½ 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 installation and may be penetrated by the screws or other mechanical devices designed to provide “hold down” strength of the waterproof membrane or roof insulating material.
Exception: Rigid metal conduit and intermediate metal conduit shall not be required to comply with 300.4(E).


As it reads in 08. 

Sorry John, I got a new toy.:thumbup:


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## JohnJ0906

Did someone get their '08 NEC on CD? :whistling2:

Thanks for posting the entire section. :thumbsup: I wasn't trying to type that much. :no:


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## Mackie

OK, so how would one go about installing the conduit 1.5" away from the roof? Is there a certain type of pipe strap that would do the trick or would you have to construct something out of 2x4's, feed the conduit through the trusses, etc?


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## nap

beam clamps and minnies or bang on minnies (caddy or B line) hanging from the bottom of the top rail.


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## ralph

Would


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## ralph

Would that be a roof deck ? I have seen alot of poured decks , as im sure tons of others have, that would not be included. This picture looks like a poured deck , but between floors. I probably am wrong , its hard to tell from pix


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## JohnJ0906

ralph said:


> Would that be a roof deck ? I have seen alot of poured decks , as im sure tons of others have, that would not be included. This picture looks like a poured deck , but between floors. I probably am wrong , its hard to tell from pix


Roof deck. Hard to drive a screw through a poured deck.... :whistling2:


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## randomkiller

JohnJ0906 said:


> Roof deck. Hard to drive a screw through a poured deck.... :whistling2:


 
Very true but for the cheaper buildings it's corragated all the way. I was doing a cut out for a unit curb and hacked through a mound of phone wiring, oops. Shouldn't have been there.


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## ralph

JohnJ0906 said:


> Roof deck. Hard to drive a screw through a poured deck.... :whistling2:


I love this site. I wish I could have the knowledge that some of you guys have.


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## JohnJ0906

randomkiller said:


> Very true but for the cheaper buildings it's corragated all the way. I was doing a cut out for a unit curb and hacked through a mound of phone wiring, oops. Shouldn't have been there.


Ouch! Hope it wasn't active....

I don't really see roofs with concrete, it is floor decks with the steel on the bottom and concrete on top - that is what I thought Ralph was talking about.


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## randomkiller

JohnJ0906 said:


> Ouch! Hope it wasn't active....
> 
> I don't really see roofs with concrete, it is floor decks with the steel on the bottom and concrete on top - that is what I thought Ralph was talking about.


It was and it put the whole dealership down. Funny thing is the installer is their own IT guy. He was ticked about the repair. The deck had been marked out top and bottom for about a week before the cut was made.


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## JohnJ0906

He was supposed to move it before the cut, then?


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## macmikeman

Another nice gimmie to the people who make and sell electrical stuff. Oh yeah, Unistrut and Bline both have 1-5/8" channel. My new name for the NEC is the National Electrical Catalog.:whistling2:


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## randomkiller

JohnJ0906 said:


> He was supposed to move it before the cut, then?


 
Yeah the GC had marked out the whole place. It was my supervisor that actually cut through all the cables in several spots to prove the point.


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## JohnJ0906

macmikeman said:


> Another nice gimmie to the people who make and sell electrical stuff. Oh yeah, Unistrut and Bline both have 1-5/8" channel. My new name for the NEC is the National Electrical Catalog.:whistling2:


I don't see this particular change like that. IMO, this is a good change.

Is screw penetrations in conduit or cable a good thing?


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## matapus

I've seen that before, but it was a peice of romex instead of pipe. My apprentice almost crapped himself when i flipped the breaker, sounded like a shot gun going off. Replaced the lighting circuit with MC and ran it along the bottom of the beams. This code change is just common sense.


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## Bkessler

I think this new code stinks, So now I cannot put pipe between the ceiling and the top of the I beam? Or screw a box up there and come into the side of it? I have ran mile's and mile's of pipe against the ceiling and this will make it more challenging. And I think that if it was that common for a screw to go through the pipe I think maybe I would here happening once in while. Has anyone here every personally seen a screw go through a conduit in this situation. I have seen the roofer cut a square hole in a roof while standing in the middle of it.. He fell about 25 feet came through the drop ceiling in a bathroom. There was a lot of blood.


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## patrick35205

It does happen, I have seen it a few times. Most recently a few weeks ago. I counted 9 screws in one run of conduit in about 20ft. If you are wedged between the top angle of the joist and the deck your pipe won't get pushed out of the way, it will get run through. How is this rule going to make overhead more challenging? Run the bottom of the joist for a rack or use the beat ons as talked about before. You can mount your box to the joist as well and still run straight into it.


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## nap

just takes away a very convenient run that is out of the way of everything else (except screws from the roofers). You could also run multiple conduits is a relativily narrow area without attachements as the sahpe of the roof restricted the pipes from moving around. Not going to work the same when running on the top of the bottom rail.

as with every other rule, we will adapt


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## Aiken Colon

macmikeman said:


> Another nice gimmie to the people who make and sell electrical stuff.


:thumbsup: 

hehe sorry I couldn't resist. Actually it is mainly the manufactuers that make a killing. They go through the new code books every year for stuff like that. Then sell stuff at jewerly type mark ups. Then a few years later the stuff is fairly priced. You can thank the Chinese for that though. They sell ya cheap tools, but they also make your small time consumables super cheap because the US manufactures have to compete with them. It just takes the imports a few years to catch up to codes usually.


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## jbfan

I have seen what looks like a spike driven into a piece of conduit. I was removing the wirs to pull in a different circuit. I pulled the white wire out from the jbox side, thouught it was kinda short, and was going to use the hot as a pull wire. When I tied to the hot with the new wire, the white was still in the pipe.
The guy on the other end begin pulling and pulled about 6 foot of wire in and it came to a dead stop. I went into the ceiling and the found the spike driven into the conduit, remove the spike and the wire pulled freely. Whe I got the rest of the white wire out, it was cut clean into, but the spike clamped it dow to the conduit, and the pipe became the netural. It was a wonder no one had ever been hurt with that circuit, and no one knew how long it had been that way.


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