# fire alarm conduit close to roof deck



## farmantenna (Nov 22, 2012)

I'm fixing an existing fire alarm system with most of the conduits attached to or very close to the roof deck and had numerous screws go through the pipe when the roof was replaced.

In the June issue of Electrical Contractor Magazine someone asked a question about this exact installation and the NEC columnist stated that because Art 760 states that only referenced sections of Article 300 within Art. 760 apply and no mention of 300.4 and roof decks is made you could install conduit within 1.5" of a roof deck for fire alarm. 

I would not do this but what do others think?

I did not look and confirm that the columnist is correct.

included a picture. some 3/4" emt had 10 and 12 #14 soild wires and severed the SLC. 4 NAC 4 SLC 2 door holder and 2 unknown use


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## tjb (Feb 12, 2014)

Roofers don’t consider what’s beneath them. They just buy in bulk whatever length screw they think will do the job, even when it gets absurd. Definitely stay a good 4-6” away from the lowest portion of the corrugation. 

Related, we were snaking a 3/4” pipe run across the ceiling and couldn’t get it through. Thought it might be a buried box (I wasn’t involved in the rough in). Turned out the hvac guys used 5” self-drillers to mount their supports. Also turns out the idiot who roughed in ran this pipe IN the joist (metal studs). Turned out also that the sheet rockers used big heavy duty self drilling screws to rock the ceiling, and these went through the pipe in many places too. Fun.


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## MikeFL (Apr 16, 2016)

That alarm should have activated as soon as he drove the screw through. 

Roofers do often consider what's below, especially those who have made mistakes before.


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## Signal1 (Feb 10, 2016)

MikeFL said:


> That alarm should have activated as soon as he drove the screw through.
> 
> Roofers do often consider what's below, especially those who have made mistakes before.


Had it been a conventional system yes.

On an addressable system this would cause an open or ground fault trouble. (He said SLC).


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## LARMGUY (Aug 22, 2010)

Hang em... hang em high!

Definitely should have thrown ground faults on that one. 

:vs_OMG: :vs_OMG: :vs_OMG:


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## MisterCMK (Jul 5, 2009)

MikeFL said:


> That alarm should have activated as soon as he drove the screw through.
> 
> Roofers do often consider what's below, especially those who have made mistakes before.


There would be a trouble right away but no alarm in this situation.


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## GrayHair (Jan 14, 2013)

I ran fire alarm conduit like this for a number of years. Also ran into the exact same problem. Drove me nuts the first time.


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## MTW (Aug 28, 2013)

I don't know if this was common in other parts of the country, but around here there's a million miles of EMT run corrugations of the sheet metal on commercial buildings built here in the last few decades. It's going to make for some interesting repair work once all those roofs need replacing.


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## Mulder (Sep 11, 2010)

MTW said:


> I don't know if this was common in other parts of the country, but around here there's a million miles of EMT run corrugations of the sheet metal on commercial buildings built here in the last few decades. It's going to make for some interesting repair work once all those roofs need replacing.


I installed at least a couple hundred miles around here and it wasn't EMT. Think blue.


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## B-Nabs (Jun 4, 2014)

Still common practice in Canada to install pipe tight to the deck. Even in the "flute" of the deck above the Wilson joists. 

Sent from my SM-G920W8 using Tapatalk


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## MTW (Aug 28, 2013)

Mulder said:


> I installed at least a couple hundred miles around here and it wasn't EMT. Think blue.


The only things that come to mind are data cable or MC Tuff cable.


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## MechanicalDVR (Dec 29, 2007)

We have all run plenty of emt on top of bar joists right under the deck.


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## Jlarson (Jun 28, 2009)

MTW said:


> I don't know if this was common in other parts of the country, but around here there's a million miles of EMT run corrugations of the sheet metal on commercial buildings built here in the last few decades. It's going to make for some interesting repair work once all those roofs need replacing.



Common here too.




We have lots of old wood buildings too with the same issues, there's a gap above each main beam that you could just sneak a 1/2" or 3/4" emt into so they would do all the lighting runs tight to the sheathing through those gaps.


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## readydave8 (Sep 20, 2009)

MTW said:


> The only things that come to mind are data cable or MC Tuff cable.


Thought he meant smurf:vs_shocked:


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## MechanicalDVR (Dec 29, 2007)

readydave8 said:


> Thought he meant smurf:vs_shocked:


Me too, classically blue!


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## nrp3 (Jan 24, 2009)

Me too.


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## Mulder (Sep 11, 2010)

readydave8 said:


> Thought he meant smurf:vs_shocked:



Yep, smurf tube. It was run on top of the roof in the corrugations. A 4 inch square was cut in the roof and a plate was screwed to the back of the 4 square. The roofer would then put the roof on. We never had a problem with the roofers screwing into the smurf tube.


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## 360max (Jun 10, 2011)

farmantenna said:


> I'm fixing an existing fire alarm system with most of the conduits attached to or very close to the roof deck and had numerous screws go through the pipe when the roof was replaced.
> 
> In the June issue of Electrical Contractor Magazine someone asked a question about this exact installation and the NEC columnist stated that because Art 760 states that only referenced sections of Article 300 within Art. 760 apply and no mention of 300.4 and roof decks is made you could install conduit within 1.5" of a roof deck for fire alarm.
> 
> ...


When you stated that only referenced sections of Art 300 apply when applying the rules of art 760, that is incorrect.

While 760 does state specific art within art 300, it also states, “and other appropriate articles of chapter 3”. Art 358 falls within chapt 3, so 300.4(E) applies to FA Systems and restricts conduit within 1 1/2” of the underside of metal roof decking.


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## CTshockhazard (Aug 28, 2009)

360max said:


> When you stated that only referenced sections of Art 300 apply when applying the rules of art 760, that is incorrect.
> 
> While 760 does state specific art within art 300, it also states, “and other appropriate articles of chapter 3”. Art 358 falls within chapt 3, so 300.4(E) applies to FA Systems and restricts conduit within 1 1/2” of the underside of metal roof decking.



Um, no.




> *760.3 Other Articles.* Circuits and equipment shall comply
> with 760.3(A) through (M). Only those sections of Article 300
> referenced in this article shall apply to fire alarm systems.


That's pretty dam clear and there's no mention of 300.4(E) in 760.


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## farmantenna (Nov 22, 2012)

thanks for code quote. I didn't look for it but it's clear


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## cabletie (Feb 12, 2011)

And this is why people don’t care about the NEC. To much BS at times. 

So if I run an empty conduit under a corrugated roof I have to keep it down 1-1/2” or fail inspection. But if I pull a fire alarm wire in it, the conduit can be screwed to the underside. 

That’s ridiculous! Anyone can see what the true intent of the code is.


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## MTW (Aug 28, 2013)

cabletie said:


> And this is why people don’t care about the NEC. To much BS at times.
> 
> So if I run an empty conduit under a corrugated roof I have to keep it down 1-1/2” or fail inspection. But if I pull a fire alarm wire in it, the conduit can be screwed to the underside.
> 
> That’s ridiculous! Anyone can see what the true intent of the code is.


The NEC has been taken over by manufacturers to sell products, plain and simple. Oh I know, some guys over at Holt's will say it's as pure as the driven snow and things get in the code only after being voted on in committees. So it must be totally free of corruption then.


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## Switched (Dec 23, 2012)

MTW said:


> The NEC has been taken over by manufacturers to sell products, plain and simple. Oh I know, some guys over at Holt's will say it's as pure as the driven snow and things get in the code only after being voted on in committees. So it must be totally free of corruption then.


They have to be right, it is virtually impossible to corrupt a voting system.


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## Wiresmith (Feb 9, 2013)

how is this the NEC's fault?

NEC is a MINIMUM standard not a design manual. does the building burn down when a low voltage cable gets a screw through it, shock hazard? does NEC forbid you from staying further away? doesn't panel alarm? MINIMUM standard, not design manual.


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## MikeFL (Apr 16, 2016)

Minimum code = As crappy as we're allowed to build.


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