Develop your base of normal and abnormal

Firefighters investigating an underground electrical vault fire use a TI to isolate the electrical problem and identify it as the source of the smoke. (Photo courtesy of Bullard.)

By Manfred Kihn

Firefighters live for the unexpected. From day to day, their job is far from routine. When a call comes in, firefighters must be ready for the unusual or the unknown and rely on their training and instincts to stay safe.

Have you ever responded to an underground fire? A firefighter friend of mine recently shared his experience with me when his crew responded to a fire in an underground utility hydro substation vault. Upon entering the underground structure, the crew was faced with maneuvering through thick black smoke and a multitude of electrical panels and general wiring, all operating in close quarters and generating a lot of heat. The environment firefighters faced bordered on thermal saturation, meaning that most or all the items in the field of view were close to or at the same temperature with very little definition apparent on the screen of a thermal imager (TI).

Investigations in such an unusual environment, such as an underground fire, are hampered since a mechanical/electrical room is not the norm and becomes an atypical comparison of multiple systems generating heat under normal operations. This scenario is not a typical baseline process of locating an item that is obviously warmer than its surrounding objects. With additional investigation, the firefighters were able to isolate the electrical problem and identify it as the source of the thick black smoke.

We often speak of locating the seat of a fire, conducting a primary search, or finding an extension of a fire in an attic or wall, but these applications usually create a sharp contrast of solid surfaces on the TI display. In many circumstances, especially in the case of investigations, the signs and clues are subtle and not as clearly defined, making image interpretation anything but automatic. I’ve talked often in this column about how a TI works. TIs process emitted infrared heat signatures that the firefighter interprets from the information shown on the TI’s screen. It’s this information that helps guide the firefighter to quickly recognize a heat signature as normal or abnormal.

Let’s look at an electrical fire scenario with another fire department. In this incident, the firefighting crew was responding to a suspected electrical issue, prompting the crew to grab the TI. Using the TI, the crew identified an electrical wiring short that was underground and only accessible through a manhole cover. The firefighters were quickly able to mitigate the situation by using the TI and correctly interpreting the information provided to them. Fortunately for the fire department, which recently battled the electrical fire in an underground substation, the crew was well-trained on image interpretation when using a TI.

Training with your TI is essential to understand the most unknown fires and what the TI is telling you. Proper training with your TI develops a knowledge base of what is normal so you can immediately recognize that which is abnormal. Use your TI on calls such as car accidents and medical calls as well as routine inspections of heaters, ballasts, freezers, stoves, furnaces, plumbing, lighting, and electrical panels to develop greater familiarity with your TI.

Before COVID-19, I spent most of my days training firefighters on how to interpret what the TI is telling them. Every application is unique, and situations may be similar but appear vastly different on your TI display because of a host of variables including the time of day, outside/inside temperatures, building materials, weather, access, and location. The more experience you have using the TI, the safer you will be.

Train with your TI in daytime and nighttime situations so you can experience how the environment, context, and ambient temperatures can affect your speed and ability to interpret what your TI is telling you. Understanding your TI is critical to making an informed decision so you can respond quickly and appropriately in the most common and unusual situations.

The evolution of thermal imaging in the fire service is trending to smaller, lighter, and more advanced TIs at a much lower cost. As TIs become even more sophisticated, firefighters have a responsibility to stay up-to-date on training so when the unknown fire situation arises, the TI tool will be the most valuable on the scene. 

Manfred Kihn is a 19-year veteran of the fire service, having served as an ambulance officer, emergency services specialist, firefighter, captain, and fire chief. He has been a member of Bullard’s Emergency Responder team since 2005 and is the company’s fire training specialist for thermal imaging technology. He is certified through the Law Enforcement Thermographers’ Association (LETA) as a thermal imaging instructor and is a recipient of the Ontario Medal for Firefighters Bravery. If you have questions about thermal imaging, you can e-mail him at

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