Which Class of Fires involves energized electrical equipment?

Fire classifications categorize fires based on their fuel source to ensure the correct extinguishing agent is used. Class C fires are specifically defined as those involving energized electrical equipment. In a data center context, this includes servers, power distribution units (PDUs), and network switches. The key characteristic is the presence of an electrical current, which acts as a continuous ignition source and poses a severe electrocution risk if a conductive extinguishing agent (like water) is applied. For this reason, non-conductive agents such as carbon dioxide or clean agents are mandated for Class C fires.

A. Class A: Involves ordinary solid combustibles like wood, paper, and plastics, not energized electrical equipment.
B. Class B: Involves flammable liquids and gases, such as fuel oil or propane, which are different fuel sources.
D. Class K: Pertains to fires involving vegetable or animal oils and fats in commercial cooking appliances.

1. National Fire Protection Association (NFPA). (2022). NFPA 10: Standard for Portable Fire Extinguishers. Section 5.2.1.3 states, "Class C fires are fires that involve energized electrical equipment."

2. Massachusetts Institute of Technology (MIT) Environment, Health & Safety. (n.d.). Fire Extinguisher Types and Classes. Retrieved from https://ehs.mit.edu/fire-safety-program/fire-extinguishers/fire-extinguisher-types-and-classes/. The guide explicitly defines "Class C: for use on energized electrical equipment."

3. U.S. Department of Labor, Occupational Safety and Health Administration (OSHA). (n.d.). Standard 1910.157 - Portable fire extinguishers. Section (d)(5) requires that "Fire extinguishers shall be provided for the protection of the employer's employees... for Class C hazards where they are present." The standard's definitions align with the NFPA classifications.