Home Fire Safety Using Thermal Imagers
By Joe DeMonte
ASNT/PdM-TIR Level III
ITC Senior Thermography Course Instructor
We have seen, in the past few years, articles on the benefits of using thermal imagers in our own homes. The rising cost of fuel and electricity has brought energy efficiency to the forefront of all of our minds. Infrared thermal imagers can trace these losses and increase the efficiency of our homes reducing money out of our pockets.
But did you know that thermal imagers can also help us to detect dangerous fire hazards before they result in damage and injury, saving money, and potentially lives?
I had just gotten back from a long trip teaching a thermal imager course, and was ready to get to bed on a Thursday night. My wife asked me a peculiar question at a very tired point in my day:
“Honey, your Mom and I smell a burning smell in her basement. Can you check it out with the thermal imager tomorrow morning?”
“Sure thing sweetheart (adding a smile and a wink)”, I replied.
When I got up for work the next morning, I called my Mom and asked her to turn on as many lights and electric appliances as she could. You see, the smell was not only in the basement, but strongest above the TV according to my wife, Mom, and Dad. That is where the house’s main breaker is kept inside a wooden cabinet and surrounded by… you guessed it… more decorative wood on the walls.
I waited about an hour to let everything become steady state. After load is added to an electric circuit, the heat generated by the product of the I2 (current squared) times the R (resistance) takes some time to increase the temperature of the components to its final value depending on the surrounding environment.
When I got to Mom’s house that morning, I powered up the thermal imager, and opened up the wooden door to the breaker cabinet. At this point in time, I do not care what temperature I see with the thermal imager. I am looking at the breaker casing and ANY unnecessary heat is a problem when talking about a residence (especially my Mom’s residence). My next step is to remove the outside metal panel from the breaker box, and with my thermal imager, trace out where the heat is being generated. The image above was taken by my thermal imager in grayscale with the cover removed.
Instead of moving spots around with my thermal imager, or adding line profiles, isotherms, or area functions, I chose another method of analysis. I changed the color palette on my thermal imager to IR Rainbow. This choice of color keeps my 256 bands of color, but separates the scale in a set of 8 color bands to distinguish the different radiances the thermal imager perceives from the bottom to the top of the scale/span. I can therefore use my thermal imager to trace the conductive patterns on the breaker casing and cable to see if it is going from the breaker to the outside, or vice versa.
The heat was being generated from the breaker and conducting up the incoming cable. My next step was to call an electrician and inform him/her of our repair needs. Just to show the electrician the path of heat, our thermal imager took a snapshot of the outside meter area above the incoming line.
The electrician arrived an hour later and de-energized the circuit. I showed him the thermal imager photos and he proceeded to perform the necessary work. He later said that he had found no “burning” or “damaged” components visually. That was not a concern to me, and I just politely asked him to clean and retighten the breaker connection and contacts for us.
When electric circuits have an increased resistance and begin building up excess heat, the problem snowballs and becomes progressively worse. Added heat can mean higher temperatures in those components, which can increase the corrosion rate and the electric resistance of copper and aluminum. I knew from past utility and substation experience that just because we couldn’t see the problem didn’t mean that it didn’t exist. Thermal imagers allow us to detect what we would miss with the naked eye. Using the information from the images taken by our thermal imager, the electrician performed the work and then re-energized the circuit.
That evening, Mom had placed load on the circuit again as I had instructed. I returned to the scene with the thermal imager and performed another inspection. We found that our electrician did EXCELLENT work as our thermal imager showed great results.
For more information on thermal imaging cameras, please visit http://www.flirthermography.com/cameras/all_cameras.asp