NEC 690.31 (E); where did it go?

ArcNSpark

Member
Guys,

Thanks in advance for reading and/or helping out.

The 2011 NEC stated in 690.31(E) that when running conduit or raceway for DC systems within a structure, we had to maintain a minimum of 10 inches below the roofline. The main purpose of this requirement was to protect any firefighters that were using a demo saw to open up the roof to let out the heat and smoke, so that they wouldn't accidentally cut through 500 VDC. (I know, the rapid shutdown should discharge the voltage in the wires, so don't all jump on me :p)

I was on a job today and in one spot, our wiring is 11" below the roof line. I checked my NEC to make sure that it was a 10" requirement, not 12", and discovered that the 10" requirement has disappeared in the 2014 code book.

I asked the local AHJ and fire marshal, but nobody knows what happened. Do any of you?

Thanks again.
 

GoldDigger

Moderator
Staff member
Possibly because the 2014 also introduces rapid shutdown so any new conductors installed under it will not be the same hazard as under earlier codes?
The true explanation will be in the CMP comments.
 

jaggedben

Senior Member
I think you just need to check your code book more carefully, it is still there but has been renumbered to something else. It's now 690.31(G), if I recall correctly, or maybe (F). There were also some errors in the printed version where in other sections it is referred with the wrong letter.
 

GoldDigger

Moderator
Staff member
I think you just need to check your code book more carefully, it is still there but has been renumbered to something else. It's now 690.31(G), if I recall correctly, or maybe (F). There were also some errors in the printed version where in other sections it is referred with the wrong letter.
I did not find it in 690.31 anywhere, nor did I find anything related in [2014] when searching for "beneath".
 

shortcircuit2

Senior Member
I noticed it gone last year and assumed it was related to Rapid Shutdown. I didn't see anything regarding a change in the ROP or ROC though. Anyone know where the 10inch rule went and why?

Anything under the roof for the first 5-feet could still be cut into by the fire department even after Rapid Shutdown.
 

ArcNSpark

Member
OP here. I was able to contact our state electrical inspector. He was surprised by my question, and after he looked into it he was able to draw the following conclusion: It's still there, but the wording and location have changed.

690.31 (G) requires the wiring to maintain that 10" clearance when "embedded within the building structure." He's concluding that that wording means the same as the 2011 code, only in a more confusing manner. He said he would contact NFPA and see if there was a difference in wording between drafts of the 2014 NEC.

Thanks for pitching in, everyone...I'm glad I wasn't the only one who was confused by this.
 

SolarPro

Senior Member
Products that are "embedded" are typically PV roofing systems. The source circuit conductors in these systems are located under the top roofing membrane, but above the insulation and roof deck. So you can't meet the 10" requirement with these systems—until you get circuits into conduit and inside the building shell.

My guess is that the language in question was removed from the NEC because it is now addressed in the fire codes. For example:

605.11.1.4 Location of marking.
Marking shall be placed on interior and exterior DC conduit, raceways, enclosures and cable assemblies every 10 feet (3048 mm), within 1 foot (305 mm) of turns or bends and within 1 foot (305 mm) above and below penetrations of roof/ceiling assemblies, walls or barriers.

605.11.2 Locations of DC conductors.
Conduit, wiring systems, and raceways for photovoltaic circuits shall be located as close as possible to the ridge or hip or valley and from the hip or valley as directly as possible to an outside wall to reduce trip hazards and maximize ventilation opportunities. Conduit runs between sub arrays and to DC combiner boxes shall be installed in a manner that minimizes the total amount of conduit on the roof by taking the shortest path from the array to the DC combiner box. The DC combiner boxes shall be located such that conduit runs are minimized in the pathways between arrays. DC wiring shall be installed in metallic conduit or raceways when located within enclosed spaces in a building. Conduit shall run along the bottom of load bearing members.
 

SolarPro

Senior Member
The quote above is from the IFC (International Fire Code). Here's the language from NFPA 1:

11.12.2.2.4 Location of Direct Current (DC) Conductors.

11.12.2.2.4.1
Exterior-mounted dc conduits, wiring systems, and raceways for photovoltaic circuits shall be located as close as possible to the ridge, hip, or valley and from the hip or valley as directly as possible to an outside wall to reduce trip hazards and maximize ventilation opportunities.

11.12.2.2.4.2
Conduit runs between subarrays and to dc combiner boxes shall be designed to take the shortest path from the array to the dc combiner box.

11.12.2.2.4.3
DC combiner boxes shall be located so that conduit runs are minimized in the pathways between arrays.

11.12.2.2.4.4
DC wiring shall be run in metallic conduit or raceways where located within enclosed spaces in a building.

11.12.2.2.4.4.1
Where dc wiring is run perpendicular or parallel to load-bearing members, a minimum 10 in. (254 mm) space below roof decking or sheathing shall be maintained.
The emphasized subsection is where the 10" language went.
 

shortcircuit2

Senior Member
Ahh...

11.12.2.2.4.4.1

that's where it went!

But here in Massachusetts when we adopted our new Fire Code, 527 CMR 1, they decided that section 11 didn't belong here.
 
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