By July 13, 2017: Alex Elting, then living on the Upper West Side, caught a dramatic moment on his cell when he videotaped the billows of black smoke and flames rising from a manhole fire at Sherman Square at 71st Street just about 100′ ft. from where he was standing.
The event caused ConEd to turn off power in over 40 buildings, affecting 600 residents. FDNY firefighters took five hours to get the fire under control and extinguished. No injuries were reported. Power was restored 12 hours after being shut down by ConEd. Manhole fires are not infrequent. Recently, in June 2024, there was a manhole fire on 71st. Street and West End and multiple manhole fires the next month on 84th Street, again on West End. In addition to manholes, ConEd also maintains transformers on the streets. These are filled with 500 gallons of transformer oil and covered by grates. When fires occur, residents in nearby buildings have reported seeing flames reach as high as five stories. When you hear the details about manhole fires from experts, there are reasons to be concerned.
In some ways – when it works – all that goes on underground in an urban environment is a marvel of complexity and technological achievement. When things break down – you might literally “fear to tread” on a city street.
FDNY Chief Frank Montagna, is undeniably an expert. He served FDNY for 43 years until he retired. He is the author of Responding to Routine Emergencies: What You Need to Know and has taught at John Jay College. His website goes into minute detail about the character of fires and emergency response.
He attributes manhole fires principally to exposure to the natural environment which causes deterioration of wires. “Overheated equipment in the summer and road salt damage during a snowy winter are typical causes. Rodent damage also.” In addition, he said, “Basically, a spark damages the insulation on cables, and the wires burn, giving off lots of black smoke and toxic and flammable gases. Explosions can occur with a three-hundred-pound manhole cover flying up into the air.
A major fire in the manhole can turn the equipment and wires in a manhole into garbage, and it will all have to be replaced. Also, fire can spread to other manholes, burning up the wires connecting the manholes.”
The realistic threat of Carbon Monoxide poisoning also comes along with the occurrence of manhole fires. According to Polywater.com,
Most manhole events – 75% – are combustion-driven low-voltage events. The most common source of energy in these events is from the anaerobic decomposition of the cable insulation and, in many cases, the duct materials. The energy is coming from gases that are created by smoldering insulation. That burning material makes enormous amounts of carbon monoxide that is pushed through the duct into nearby buildings.
The article also notes that “We all know that carbon monoxide is toxic, but it is also incredibly flammable. Carbon monoxide has been forced into buildings or adjacent structures and has caused serious explosions. The gases are the more significant hazards.” According to Chief Montagna Carbon Monoxide is the greatest threat in these fires as it is toxic, with even low doses causing fatalities.
FDNY does not typically determine the cause of these fires. That is up to the utility, according to Chief Montagna. Rapid response to manhole fire is basically the only way that these fires can be managed. And, the FDNY’s and ConEd’s goal is to work seamlessly together
“ConEd workers work inside of manholes with live power. FDNY does not turn off the power to manholes. Firefighters typically do not enter a live manhole. To save a life, without ConEd on the scene, we might.” Chief Montagna explained in more detail, “ConEd will usually cut the feed lines from manholes located adjacent to the one on fire to the manhole when necessary, rather than turning off power to a large area. When they are finished, they will reattach the feeders.” Arriving at the scene of a manhole fire, FDNY immediately readies hose lines to flood the manhole and takes Carbon Monoxide readings at surrounding buildings, setting up an exclusion area and, when necessary, evacuating residents – even pulling them from their beds.”
Firefighters are all trained in utility-related fires. That includes manholes, overhead, and substations. “We are not experts, and when we are called to these fires, we call ConEd said Chief Montagna. “Frequently, we get there first and must operate alone until they arrive, they are the experts. We, however, are responsible for life and property. We operate well together because we are trained by ConEd experts in Probationary ‘Proby’ Firefighter School and again at each promotion, Lieutenant, Captain, Battalion Chief and Deputy Chief.”
Chief Montagna emphasized the importance of good communication between ConEd and FDNY. ConEd has employees dedicated to working with the fire department at major utility emergencies. They wear white helmets and are known as ‘White Hats.’ These same people do the FDNY training relating to electrical and underground fires. As a result, we work well together. During the training sessions, they explain their needs and concerns, and we explain ours.”
Asked about the complex challenges of manhole fire prevention and mitigation, Stuart Hanebuth an expert in the field and former ConEd manager, pointed to the authoritative IEEE P2417 Guide for Early Detection Mitigation, Preventive Measures and Response to Smoke, Foreyand Explosions in Underground Electrical Structures (February 2022). Having led the development of this guide, he noted that “The methods outline (for practitioners) includes many of the measures that ConEd has pioneered, including the understanding of the electrochemistry of events early detection and modeling of event dynamics.”
From the viewpoint of a cautious NYC resident walking on the street, is any sign of steam coming out of a manhole a cause for concern – a reason to call FDNY or ConEd?
“Yes” Chief Montagna answered. “ConEd has some high-pressure steam manholes that sometimes leak steam for a number of reasons. These are located in downtown Manhattan. A minor leak is no big deal. You can get steam from an electric manhole sometimes. One reason is if a transformer is heating up and it is wet. The water turns to steam. It could be nothing or it could be something. Since you don’t know the cause, call ConEd and call the fire department.”
On the question of the ongoing development of precautionary and preventive measures, Chief Montagna said, “ConEd has taken some measures to make manholes safer. They do inspections and have monitoring equipment that keeps tabs on electric manholes. They also have tried tethering manhole covers so they do not blow up into the air and kill people and pets. I’ve heard they are exploring new types of monitoring techniques. They are taking steps to mitigate leaking electricity that can charge the manhole cover and kill people. A lawsuit was filed by the father of one victim who came to help his dog after she was injured by an electrified manhole cover. Now they have vehicles that ride around the city checking for electrical leaks in manholes.”