BY MICHAEL N. CIAMPO
With the onset of spring and melting snow and rain showers, we’ve had our share of runs that involve manhole fires or emergencies. The road salt combines with the water and makes a corrosive mixture that seeps into the manholes or transformer vaults in the street, eating away the wires’ protective casing and coming in contact with the live wires. During this time of year, we will respond to numerous calls for smoking manholes. Many may involve steam or light smoke issuing from them; electrical arcing from the mixture that’s running down into them; or smoke issuing under pressure, evolving into a fire or an explosion.
As we responded to a report of a manhole fire, the dispatcher informed us of receiving numerous calls that the cover had blown. Arriving on the block, we could see the acrid black smoke and some small flames escaping out of the hole. Plus, there was bright white and purple arcing and loud hissing and popping noises.
We approached the cover with care so as not to step on any other cover or metal object (curb edging metal strip, utility shut-off covers, or sidewalk grating) and sized up if others were in the vicinity; suddenly, the manhole let out a loud muffled “BOOM,” startling many of us even though we were proceeding cautiously! Since the smoke was issuing on the corner near a traffic light, we reminded the crew to use caution in that area. There have been times when the burning wires underground have pushed up carbon monoxide (CO) through the conduit and, when the signal changed, a spark inside the control box caused a small explosion.
Approaching the hole and using the thermal imaging camera (TIC), we could read the heat erupting from the hole; the road pavement in the area was also showing signs of heat a few feet around the rim. We radioed the chief that there were no cars in the immediate vicinity and that this was a transformer vault rather than a manhole so he could notify the utility company.
As one member cordoned off the area with barricade tape, the truck split into two teams to check the surrounding occupancies’ basements. Teams were wearing self-contained breathing apparatus and were equipped with CO meters, because these fires often emit CO back into the buildings through the electrical conduit running under the sidewalk to the building.
As our team entered the basement of this large multiple dwelling, we noticed that the lights were flickering; then, the whole building’s electrical service went out. Proceeding into the basement with our flashlights on, we began to hear loud noises. One member said, “Did you just hear someone break a glass?” Another said, “I hear loud popping.” Turning the corner in a hallway, we could smell the burning wires, and our CO meter started to go off. We immediately went back a few feet and let the chief know what we had and donned our face pieces.
Now that we were on air, we continued our search. As we turned the hallway and traveled a few more feet, we saw flashes of white light in a room in front of us. Moving slowly, we heard the loud sounds of arcing and popping; the closer we got, the louder they became. Getting near the door, we directed the TIC into the room. All of a sudden, we heard a loud pop and the sound of breaking glass; the room lit up like a lightning bolt, lighting up the night’s sky. We could see that there was an electrical emergency in the meter room and the sounds of breaking glass were the individual apartment meters exploding. The wires burning underground had compromised the power feed to this building, and we were in a defensive posture at the moment and still in awe of what we were watching. The popping and arcing seemed to stop, and one member asked if we were going to shut down the building’s main electrical panel. We were not, because if CO was built up in the panel box, it could explode if a spark occurred while we shut the power down.
We informed the chief of the situation and let him know that we would continue with a primary search and ventilate the high levels of CO in the basement. Our search proved negative. The chief ordered us outside once we told him that the electrical room was an isolated room with a concrete ceiling.
Because of the utility company’s backlog of runs, we were slated for the next available crew. The other exposures checked out fine, although another building on the block lost power while we were operating. While waiting for the utility company, members checked the elevators in each building to ensure no one was trapped and performed recon of the electrical meter room. The engine stretched a precautionary line to the basement of the multiple dwelling and another line to the street.
The utility company showed up quickly, and we assisted. The crew suggested we try expelling a few dry chemical extinguishers into the vault, but that had no effect. So the plan was to use a hoseline without a nozzle, off a hydrant, and flood the manhole; before allowing anyone to touch the hydrant, the utility crew checked it to make sure it wasn’t electrically charged. After we discharged the water, we performed secondary searches in the basements to get meter readings and checked the electric panels with the TIC. The CO levels had dropped; all panels showed no indications of heat. The utility crew began its work and joined in our informal critique; we both commented on the brutal winter and busy spring, with plenty of manhole madness.
MICHAEL N. CIAMPO is a 29-year veteran of the fire service and a lieutenant in the Fire Department of New York. Previously, he served with the District of Columbia Fire Department. He has a bachelor’s degree in fire science from John Jay College of Criminal Justice in New York City. He is the lead instructor for the FDIC Truck Essentials H.O.T. program. He wrote the Ladder chapter and co-authored the Ventilation chapter for Fire Engineering’s Handbook for Firefighter I and II (Fire Engineering, 2009) and is featured in “Training Minutes” truck company videos on www.FireEngineering.com.
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