A design package lands on a plant engineer’s desk marked “Class I, Division 2,” and the label alone doesn’t tell the reviewer much. What matters is whether that classification matches what actually happens inside the building, and whether the equipment specified for it would hold up if an insurer or the local fire marshal asked to see the reasoning behind it. Get it wrong in one direction and the owner pays for explosionproof equipment where it isn’t required. Get it wrong in the other direction and a warehouse full of aging inventory is running on gear that was never rated for the vapor it’s sitting in.

How a rickhouse earns its H-3 classification

Wooden barrels aren’t sealed pressure vessels. The wood breathes, and over years of aging, ethanol vapor works its way into the warehouse air. Under the International Building Code, Section 307.5 (Group H-3), a building storing “Class I, II or IIIA flammable or combustible liquids that are used or stored in normally closed containers or systems pressurized at 15 psig or less” gets classified High-Hazard Group H-3. Bourbon and most other whiskeys, at typical barrel-entry proof, put ethanol above roughly 16 percent ABV, which puts it in Class 1B or 1C flammable liquid territory. Once the quantity in a room or building exceeds the Maximum Allowable Quantity for that class, H-3 classification isn’t optional. It’s what the code requires, and it’s the reason a rickhouse gets a different design review than a standard commercial warehouse.

Division 2 versus Division 1, and why it changes the equipment list

H-3 occupancy classification and electrical area classification are two different determinations, and both have to happen before anyone can size an equipment list. Area classification asks a narrower question: where does an ignitable concentration of vapor actually exist, and under what conditions? Class I, Division 1 means ignitable concentrations exist under normal operating conditions. Class I, Division 2 means they exist only under abnormal conditions, such as a barrel failure, a spill, or a ventilation system going down. Most rickhouse space is classified Division 2 because barrels stay intact and vapor release under normal operation is limited. But that classification isn’t a single label stamped across the whole building. It depends on where vapor can accumulate and under what conditions, which is why a design should show classification boundaries tied to actual airflow and barrel handling, not just a blanket note on the cover sheet.

The division distinction is what drives most of the cost difference between hazardous-location designs. Division 1 equipment can always be installed in a Division 2 location of the same class and group. Division 2 opens up a narrower and cheaper path that Division 1 doesn’t: general purpose equipment, if the designer can document that it won’t ignite anything under normal conditions. That second path is where a lot of design review time should go, because it’s also where corners get cut.

What OSHA 1910.307 actually permits

The federal rule governing this is OSHA 29 CFR 1910.307, “Hazardous (classified) locations”. Under 1910.307(e), “Equipment that has been approved for a Division 1 location may be installed in a Division 2 location of the same class and group. General-purpose equipment… may be installed in Division 2 locations if the employer can demonstrate that the equipment does not constitute a source of ignition under normal operating conditions.”

Read that second sentence carefully, because it’s doing a lot of work. It doesn’t say general purpose equipment is allowed in Division 2. It says it may be allowed, if the employer demonstrates the absence of ignition risk. That’s a documentation burden that sits with the facility, not a default the equipment gets to claim on its own. OSHA’s rule incorporates NFPA 70, the National Electrical Code, by reference for equipment groups, wiring methods, sealing, drainage, and the accepted protection techniques: explosionproof, purged and pressurized, nonincendive, intrinsically safe, and hermetically sealed. A design that specifies one of those five techniques for a given device is answering the question OSHA is actually asking. A design that specifies general purpose equipment without a documented demonstration is leaving the burden of proof unmet.

What changed in NFPA 30’s 2024 edition

Fire protection design for rickhouses has run for years on engineering judgment borrowed from general flammable-liquid storage rules, because no code had rules written specifically for barrels. That changed with NFPA 30, Flammable and Combustible Liquids Code, 2024 Edition, Chapter 16, renamed from “Automatic Fire Protection for Inside Liquid Storage Areas” to “Automatic Fire Protection for Control Areas, Liquid Storage Rooms, and Liquid Warehouses.” For the first time, the chapter includes dedicated fire protection tables for distilled spirits stored in wooden barrels, on end, on side, or laying down. Those tables were developed largely from full-scale fire test data contributed by FM Global, not extrapolated from other commodity classes. The 2024 edition also defines a “small distilled spirits facility” as one under 7,500 square feet, a threshold that didn’t exist in code language before.

One limit matters as much as what the chapter added. Chapter 16 does not apply to Class IA liquids, because no full-scale fire tests exist for that class. If a facility’s product classification falls into Class IA anywhere in the storage area, the new barrel-storage tables in Chapter 16 simply don’t cover it, and the designer needs a different basis for the fire protection scheme. A design that cites Chapter 16 without addressing that gap hasn’t finished the job.

Where general purpose equipment does not belong

The demonstration requirement in OSHA 1910.307(e) is not paperwork for its own sake. The scale of loss when a rickhouse does ignite is why the classification gets scrutinized at all. On July 2, 2019, a fire destroyed 45,000 barrels of bourbon in a single rickhouse at a Beam Suntory warehouse complex in Woodford County, Kentucky. Initial reporting pointed to a lightning strike during a storm as the cause, but that cause was preliminary and unconfirmed. No injuries were reported (Associated Press via ABC News, 2019). Whatever ignited that fire, the loss shows what’s at stake in a structure built almost entirely of wood and holding tens of thousands of gallons of ethanol vapor over its lifetime. That’s the environment general purpose equipment has to survive, not on paper, but during whatever abnormal condition eventually shows up. A demonstration that equipment “does not constitute a source of ignition under normal operating conditions” is not a statement about a good day. It’s a statement about every day, including the ones with a failed gasket or a downed fan.

Questions to ask before accepting a design

A facility manager reviewing a proposed design doesn’t need to reclassify the building. The questions below are enough to find out whether someone already did the work correctly.

1. What document establishes the electrical area classification, and does it name Division 2 specifically, rather than a general phrase like “hazardous location”?
2. Where exactly does the classification boundary fall inside the building, and what airflow or barrel-handling condition justifies drawing it there?
3. For every piece of general purpose equipment shown on the drawing, where is the written demonstration, required under OSHA 1910.307(e), that it won’t ignite anything under normal operating conditions?
4. For every other device, which protection technique is specified: explosionproof, purged and pressurized, nonincendive, intrinsically safe, or hermetically sealed, and does that technique match the division and group assigned to that location?
5. If any product stored in the building is Class IA, what fire protection basis is being used instead of NFPA 30 Chapter 16, since that chapter doesn’t cover Class IA liquids?
6. Has the authority having jurisdiction reviewed and approved the classification drawing itself, separately from the fire alarm and controls design built on top of it?
7. Has the property insurer seen the classification and the equipment list, and do their requirements match, or exceed, what’s shown on the drawing?

No design should be accepted on the strength of a label. It should be accepted because the answers to these seven questions hold up under someone else’s questions too, including the AHJ’s and the insurer’s. No contractor should tell a facility manager a design will pass review before it’s been through the AHJ and the insurer. Nobody can promise that. What a design can do is answer these questions clearly enough that both of those reviews go faster.

What this looks like when it’s handled well

Versys has spent years designing fire alarm systems for Kentucky bourbon warehouses under C1D2 and H-3 classification, working alongside commercial industrial electricians on the equipment and wiring methods those classifications require. That work extends past the alarm panel into the industrial controls layer: ethanol sensors, programmed responses tied to those sensors, fire alarm interlocks to fans and louvers, and gas detection integrated with the exhaust system. None of that replaces the facility’s own responsibility to confirm classification and design with its AHJ and its insurer. It does mean the classification questions above get answered in the design documents before anyone has to ask them in a review meeting.

Facility managers with a design in hand, or a rickhouse due for a classification review, can call Versys at (270) 358-2200 to walk through it before signing off.