Emergency Generator Fuel Oil Storage – Control Area, Group H (High Hazard Occupancy), Or Other?

How are the quantities of generator fuel oil storage regulated by the building code?

The most common emergency generator fuel source we see utilized on projects is diesel, which is classified as a Class II combustible liquid, in accordance with International Building Code (IBC) hazardous materials classifications. The storage or use of Class II combustible liquids within a building is regulated either as part of a control area, or as a High-Hazard Group H occupancy if control area maximum allowable quantity (MAQ) limits are exceeded. One exception to this is fuel oil storage. Specifically, IBC Table 307.1(1) footnote i exempts fuel oil storage complying with Section 603.3.2 of the International Fire Code from control area MAQ limits. There are two major thresholds to consider when determining if IFC Section 603.3.2 can be satisfied:

  1. The aggregate capacity of all tanks is not permitted to exceed 660 gallons, or 3,000 gallons if in protected above-ground tanks (integral secondary containment, thermally insulated, listed per ANSI/UL 2085) complying with IFC Section 5704.2.9.7.
  2. Tanks in basements must not be located more than two stories below grade plane.

If both above criteria cannot be satisfied and assuming the fuel storage quantity exceeds control area MAQ limits, a High-Hazard Group H occupancy would be required. This does however come at a cost with potential upgrades to room fire resistance ratings, ventilation, and emergency alarms to name a few.

Irrespective of whether a High-Hazard Group H occupancy is triggered, it is important to note that compliance with NFPA 37, Standard for the Installation and Use of Stationary Combustion Engines and Gas Turbines, is required. The criteria within this standard would apply in addition to the requirements previously outlined above with examples such as increased room fire resistance ratings, specialty ventilation, and spill containment.

If you have any questions or would like assistance on the generator fuel oil storage approach for your project, please do not hesitate to contact us info@crcfire.com.