[RE-wrenches] My AHJ insisting on "Flammable Vapor Ignition Resistant" 18-inch requirement

Thu Sep 11 14:12:14 PDT 2025

Jason's well-laid arguments won the day here. Very much the logic you laid out and the AHJ reluctantly conceded the point.

He tried going directly to Mechanical Code but I said no, pertinent sections of IMC are in IRC, Ch 12-24. Then he tried saying that IFC had more stringent requirements that R330 (ESS) but I said, no you won't find any reference to 18" in the ESS section of it. And the individual sections of IRC Ch12-24 spell out the 18" inch reqt when appropriate but that is absent from R330.

Really appreciate the great feedback, Jason. If nothing else, this was a good exercise in Code refresher for me and to navigate a way-too-complex IRC that is too easily over-applied by an AHJ. At least my own city's AHJ (the site of the project) was open to robust debate and thick-skinned enough to reverse himself.

Phew...this would have been an expensive "de-retrofit" And I'll say again, the Enphase ESS in a six battery config is awesome. 24,000-watts of continuous power and "whole house" backup is easily gained. Little long time-wise to wire the six together but it's a nice setup. Very pleased with it.

Howard "Scot" Arey
Owner, Solar CenTex
254-300-1228

________________________________
From: RE-wrenches <re-wrenches-bounces at lists.re-wrenches.org> on behalf of Ray Walters via RE-wrenches <re-wrenches at lists.re-wrenches.org>
Sent: Thursday, September 11, 2025 1:39 PM
To: re-wrenches at lists.re-wrenches.org <re-wrenches at lists.re-wrenches.org>
Cc: Ray Walters <ray at solarray.com>
Subject: Re: [RE-wrenches] My AHJ insisting on "Flammable Vapor Ignition Resistant" 18-inch requirement

I second Jason's sentiments.  We need to 'gently' but firmly push back on all these extra code requirements, otherwise we'll be so buried, we won't be able to stay in business.  We've been under attack from various factions since the 1980s, who have thrown unreasonable requirements at us.  Recall utilities requiring gold plated disconnects or million dollar liability policies to grid tie. Many folks are trying to politicize our industry, and we need to let everyone know that energy independence is very American.  So is safe, affordable construction.

Ray Walters
Remote Solar

On 9/11/2025 4:17 AM, Jason Szumlanski via RE-wrenches wrote:
I have had AHJs try to shoehorn solar panels into the mechanical code before. I think your best bet is to argue the applicability of the mechanical code entirely. Expressio unius est exclusio alterius / The expression of one thing implies the exclusion of others. If the IRC authors wanted M1307.3 to apply to ESS, they would have said so in R328.

I would go with something like:

This equipment is a UL 9540-listed energy storage system, specifically tested to the UL 9540A standard. The applicable section of the IRC is R328 (or 2023 IRC Section 327), not the mechanical code. Chapter 13 applies to mechanical appliances such as HVAC equipment or combustion devices—not sealed electrical ESS. This product does not fall under the scope of M1301.1 and is not subject to M1307.3.

If they don't accept that, I would ask them to:

Point to the section in M1301.1 that covers ESS. Explain why R328 doesn’t apply, despite being specifically titled “Energy Storage Systems.”

On another subject, I have been involved in another AHJ battle regarding protection against vehicular traffic, and I have a blog post on the subject coming out soon. Fortunately, the next Florida Building Code draft mirrors the IRC, which includes a clear schematic that clarifies the requirements.

Good luck, and don't let them win!

Jason Szumlanski
Principal Solar Designer | Florida Solar Design Group
NABCEP Certified Solar Professional (PVIP)
Florida State Certified Solar Contractor CVC56956
Florida Certified Electrical Contractor EC13013208

On Tue, Sep 9, 2025 at 3:46 PM scot.arey--- via RE-wrenches <re-wrenches at lists.re-wrenches.org><mailto:re-wrenches at lists.re-wrenches.org> wrote:
Seeking your suggestions and direction. My AHJ - after acknowledging that the Enphase 5p battery has a floor mount option - now insists that it must be 18-inches above the garage floor unless I can produce something that says it is "Flammable Vapor Ignition Resistant."

We all know there is no open flame from an ESS and I know the 9540A depicts a battery at 6-inches.

Anybody run into this and have suggestions on what I might show back to the AHJ?

Howard "Scot" Arey
Owner, Solar CenTex

NABCEP PV Installation Professional
TECL 29755
254-300-1228
[cid:part1.B68JO3LC.NlMT0vw6 at solarray.com]

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