PV roof pathways

Hi,

So...this comes up every now and again when we are cramming into a tight roof and I scratch my head not so sure about it. The way I read the code (IFC 2015), all roofs need a centerline pathway; however, nobody else seems to interpret it that way. The installer says its only needed if the array is greater than 150', which in my eyes is something entirely different, that is a venting pathway specifically. I say OK get FMO approval and we'll stamp it as FMO approved exemption. Every time they get the approval and questioned why they even asked. What am I missing or is everyone else just missing it because that's how everyone does it and the FMOs have never thought about it that detailed in our area.

Thoughts?


605.11.1.3.2 Pathways.
The solar installation shall be designed to provide designated pathways. The pathways shall meet the following requirements:

  1. The pathway shall be over areas capable of supporting fire fighters accessing the roof.
  2. The centerline axis pathways shall be provided in both axes of the roof. Centerline axis pathways shall run where the roof structure is capable of supporting fire fighters accessing the roof.
  3. Pathways shall be a straight line not less than 4 feet (1290 mm) clear to roof standpipes or ventilation hatches.
  4. Pathways shall provide not less than 4 feet (1290 mm) clear around roof access hatch with not less than one singular pathway not less than 4 feet (1290 mm) clear to a parapet or roof edge.

605.11.1.3.3 Smoke ventilation.
The solar installation shall be designed to meet the following requirements:

  1. Arrays shall be not greater than 150 feet (45 720 mm) by 150 feet (45 720 mm) in distance in either axis in order to create opportunities for fire department smoke ventilation operations.
  2. Smoke ventilation options between array sections shall be one of the following:
    2.1.A pathway 8 feet (2438 mm) or greater in width.
    2.2.A 4-foot (1290 mm) or greater in width pathway and bordering roof skylights or gravity-operated dropout smoke and heat vents on not less than one side.
    2.3.A 4-foot (1290 mm) or greater in width pathway and bordering all sides of nongravity-operated dropout smoke and heat vents.
    2.4.A 4-foot (1290 mm) or greater in width pathway and bordering 4-foot by 8-foot (1290 mm by 2438 mm) “venting cutouts” every 20 feet (6096 mm) on alternating sides of the pathway.
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
To give you my blunt opinion, I think the installer's interpretation is common because the provision that you are highlighting just seems dumb. We all know what it says. It just doesn't make any obvious sense. And if installers are getting fire marshall approval for exceptions every time, well, that just proves the point.

Compared to other pathways, does a centerline pathway have a special purpose that particularly requires it to be at the centerline? How far off the centerline is close enough? What if there are existing non solar obstructions on the centerline? If there are pathways every 150ft then why does a particular pathway need to be near the centerline? If it's acceptable to have an array that's 150ft x 150ft on a large building why is not acceptable on a building that is smaller than that in each dimension? Suppose I have a building that snugly fits three 150ftx150ft arrays in a line; why would two pathways across in the middle be inadequate but three is required? Compare to a building that fits four such arrays in a line; why does this building get to take full advantage of the 150ft allowance but the other one doesn't? Suppose I have a building that's 200ft by 40ft; why do I need a centerline pathway in both directions?

What about buildings that are L shaped, or U shaped, or otherwise not rectangular or symmetrical? Buildings with multiple roof levels?

Maybe a firefighter will chime in as to why the actual centerline of the building is special for firefighting operations in some way. If so, that would educate me as to something that I wager is far from obvious to the rest of us.

Obviously the rule is most frustrating when it means reducing the total number of panels that can be put on a building, which is particular stark when the building is less than 150ft in either direction. It seems the provision would make more sense if it did not require a centerline pathway that is shorter than 150ft in length. That is, if there is any real reason that a centerline pathway improves safety where the other pathway requirements don't.
 
So that's the thing, I was actually a volunteer FF for a while. I could say that as written it doesn't really address anything, I would think the biggest thing that would concern me, which I assume is part of the rational of the 150' array, is egress (though they do have venting requirements at 150' as well to be able to vent frequently enough) - something goes south you need another way to get out and you may be in smoke so you wouldn't see a skylight or a hatch or a vent-pipe that could cause a tripping or larger safety hazard (like falling through a skylight).

You raise the bigger point though, sometimes there is no clear path from one side to the other anyway. If it were for egress and thought out, it would seem there should be some more provisions behind it....to your point being center or not has nothing to do with it, just being a reasonable distance from where the FF is at the time they need to bail and over top of a sound structure which the fire likely hasn't affected yet - in which case the reasonable distance should be specified. Anything over 150' I simply just break up to get something near center that has the same number of break points. Generally speaking, I would also say provisions should also consider building occupancy because I can tell you now, any smart incident commander isn't going to send his guys on the roof of a full involved building with no one in it - they would do an external attack and protect surrounding structures as their primary goal. I would also say exemptions for buildings with skylights reasonably frequent would also make sense; honestly with no as-built of the PV system handy but with direct 4 ft paths to skylights from the edge of the building, you'd be crazy to vent anywhere else, in and out and no need to lug equipment other than a Halligan tool (which is like a hitchhikers towel equivalent - you'd be asking for trouble to go anywhere without it).

With that said there are plenty of other conflicts with research vs. smoking and venting procedures...even conflicts with engineered heat and smoke venting devices where it has been proven that they are more of a detriment in a fully sprinkled building yet the code still requires it.

Too many cooks in the kitchen...
 
Sorry to wake up the dead on this but get this coincidence...

The project that sparked (no pun intended) this question ended up having a fire on the top floor of that building, go figure! The fire was unrelated to the PV but the PV became a huge topic of discussion because the FD didn't feel they had adequate room to work or vent.

All of the sudden they want to listen when I ask them questions about pathways :rolleyes: :LOL:.

FWIW if you have a discussion in the future with an FD or the FMO, the biggest thing they didn't understand was rapid shutdown (something we spend a lot of money on and the training never makes it to the people who it is intended for). The system was still work in progress when it happened, so there could have been confusion anyway (AC side wasn't done yet so no disconnect on the building) but when I explained the panels were all isolated so voltage is limited to a safe level, and they realized they could just toss sections of racking where they wanted them with low risk of shock it was like I just told them they won the lottery.
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
I've definitely daydreamed about a side career in explaining rapid shutdown to fire fighters. Problem is they have to rely on unreliable labeling and placarding and three different generations of requirements (or lack thereof) on existing installations. Add energy storage to the mix and I wonder how helpful it can really be when the adrenaline is flowing.
 

pv_n00b

Senior Member
Location
CA, USA
There is a lot of firefighter training on PV, ESS, EVs, etc. that is available, both in-person and online. But that does not mean everyone is taking advantage of it. If the folks who set up the training for your local firefighters don't schedule it then it won't happen.
 

BandGap1.1eV

Member
Location
East Coast
I've definitely daydreamed about a side career in explaining rapid shutdown to fire fighters. Problem is they have to rely on unreliable labeling and placarding and three different generations of requirements (or lack thereof) on existing installations. Add energy storage to the mix and I wonder how helpful it can really be when the adrenaline is flowing.

Nearly every recent experience I've had with Fire Chiefs have been negative. On a recent site walk the Chief chimes in "Why is this the first time I'm hearing about solar on this building". It wasn't. He signed off on the permit submission.

The common retort when trying to discuss access pathways, walkways, laydown areas, rapid shutdown, etc is nearly always some derivation of "how many of my guys do you want to be responsible for killing!?"
 

pv_n00b

Senior Member
Location
CA, USA
When I started out in PV almost every interaction with a building department AHJ was negative. They did not understand PV, since they did not understand it they thought it was unsafe, they did not want to approve anything that they thought was unsafe. It took years of educating AHJs to get to where we are today where to most AHJs PV is just another building system. We need to educate firefighters about how safe PV is for them. It's going to take years of being patient, answering the same questions over and over, and dealing tactfully with people who don't understand PV and think that it is unsafe.
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
Nearly every recent experience I've had with Fire Chiefs have been negative. On a recent site walk the Chief chimes in "Why is this the first time I'm hearing about solar on this building". It wasn't. He signed off on the permit submission.

The common retort when trying to discuss access pathways, walkways, laydown areas, rapid shutdown, etc is nearly always some derivation of "how many of my guys do you want to be responsible for killing!?"
It's like their trump card. One day I'll say, "Tell me how many have already died in a PV related structure fire, and I'll give you a number."
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
<Knocking vigorously on my wooden desk> The only significant issue with a fire marshal I have had in the past few years was over whether the 48" perimeter clearance should be measured from the inside or outside of a parapet. Inside prevailed and I lost a few modules. It makes sense.
 
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