Fires are organized into classes that describe either their primary cause or the type of material that burns. The unique danger posed by a Class C fire, by definition, involves energized electrical equipment—more specifically, “appliances and wiring in which the use of a non-conductive extinguishing agent prevents injury from electrical shock.” In simpler terms, a Class C fire can occur anywhere there is electrical wiring or equipment in use. They can be caused by faulty wiring, short circuits, and similar issues.
The electrical shock bit is worth emphasizing, since it means attempting to use water on a Class C fire is an extremely dangerous idea. Water, after all, can conduct an electrical current. So, what fire suppression system is appropriate for this class of fire? We are answering some common questions about electrical fire protection, so you can keep your facilities, equipment, and people safe.
What Is a Class C Fire Extinguisher?
A Class C fire extinguisher is one that is designed to be safely used in the presence of energized electrical equipment, often found in industrial settings. Using the right type of extinguisher for Class C fires is paramount, so you don’t create any additional hazards—like electrical shock—in the process. In certain industrial settings, it’s also vital to consider factors such as not using any fire suppression agent:
- That conducts electricity.
- That can potentially damage sensitive equipment.
- In a closed, occupied space that can be toxic to humans.
Which 2 Types of Fire Extinguisher Should You Use on Live Electrical Equipment?
Among standard fire extinguisher types, the three recommended options for Class C or electrical fires are:
Clean agent systems use gaseous fire-suppressing agents, which are electrically non-conductive and leave no residue after their deployment. These systems are especially useful for server rooms and similar areas, where other fire suppression methods could endanger people or risk damaging valuable equipment.
A dry chemical fire extinguisher separates an electrical fire’s fuel source from the surrounding air by creating a barrier of chemical dust, effectively smothering it. When a dry chemical extinguisher is discharged, it can leave a powdery residue that can damage some equipment if not promptly and properly cleaned afterward.
A third potential option would be a CO2 fire extinguisher, which uses non-flammable, pressurized carbon dioxide gas to displace the oxygen that keeps a fire burning once ignited. However, there are disadvantages to using a CO2 fire extinguisher for a server room or similar setting. The discharge of CO2 can cause a cold shock which causes freeze water vapor in the atmosphere and when in close proximity to various components, the freeze water will attach. Once the space warms up it introduces water into those components. In addition, the CO2 is concentrated and floods the area, which is toxic to humans. For these reasons, CO2 extinguishers are inappropriate for occupied spaces and around sensitive equipment.
With each of these fire extinguisher types, it’s important to take their potential disadvantages into consideration. While they will certainly work to extinguish a fire, you’ll want to minimize the chance of damaging equipment or endangering humans.
Can You Use a Foam Extinguisher on a Class C Fire?
No, foam extinguishers are only appropriate for Class A and B fires, since one of the substances they contain is water. Using one on an electrical fire would present a shock hazard.
So far, we’ve identified four types of fire extinguisher or suppression systems that would effectively put out an electrical fire, but not without presenting dangerous conditions or damage to equipment in the process. What’s really needed is a clean agent fire suppression system, which is detailed below.
What Is a Clean Agent Fire Extinguisher?
A clean agent fire extinguisher or suppression system uses what’s known as a “clean agent” in order to suppress a fire without risking damage to equipment or people. More specifically, the National Fire Protection Association (NFPA) defines a clean agent as “an electrically non-conducting, volatile, or gaseous fire extinguishant that does not leave a residue upon evaporation.”
Clean agent fire extinguishers work quickly and effectively to put out a fire, without leaving any residue behind or endangering people who work in occupied spaces. This increases workplace safety greatly, and minimizes potential disruption/downtime.
The three most common clean agents are:
- FM-200™, also known as HFC-227ea
- 3M™ Novec™ 1230 fire protection fluid (FK 5-1-12)
- Inert Gases, such as argon and nitrogen
What Fire Suppression System Is Best for Class C Fires?
All things considered, the best fire suppression system for Class C fires is one that can extinguish fires…
- Quickly and effectively.
- Without posing the risk of electrical shock.
- Without risking damage to sensitive equipment/facilities.
- Without risking human health.
- Without requiring extensive clean-up.
Modern fire suppression systems using clean agents are ideal for use within electrical enclosures, server racks, and server or electrical rooms. They’re easy to install and maintain, and can effectively stop a Class A, B, or C fire before it can spread and become catastrophic. Not only are installation and maintenance quick and easy, but when a fire is detected within an electrical panel or similar enclosure, the system automatically and immediately suppresses them to protect your equipment, facilities, and people.
