Fire in the Hole!
Transformer vault explosions involving carbon monoxide require specific size-up & tactics
By Freddie LaFemina

We all understand the major difference between transformer vaults and manholes: Manholes can have multiple types of utilities inside their spaces: gas, water, steam, etc. Underground transformer vaults store electrical equipment.

But when there’s a fire in either one, which occurs quite frequently, things can go from bad to worse very quickly. Unfortunately, members can sometimes become complacent and let their guard down during these “routine” incidents, which can cause major problems on the fireground.

What to Do
If and/or when you respond to a smoking manhole in your jurisdiction, and upon arrival, you find both smoke and fire issuing under pressure from the manhole cover, always follow your SOPs. If you’re the supervisor of your engine company, have the members identify a positive water source, stretch a handline, charge it and stand at a safe distance, anticipating an explosion or an increase in pressure from the manhole.


The incident commander should then assign the next-arriving unit to take carbon monoxide (CO) readings in any nearby structure(s) that may be affected by a CO leak. Any abnormal levels should cause an implementation of your department’s tactics for CO emergencies. Remember: Carbon monoxide is always produced at a fire.

Depending on the CO levels found, you may have to evacuate the structure(s) and identify the source of the CO. Note: The structures should never be re-occupied until safe readings are generated on the meter. If the utility company is on scene, confer with them as well before letting occupants back into the structure.

Remember to check for fire in affected structures, as fire could extend from the manhole into the structure and vice-versa, and check adjacent manholes in the vicinity of the affected manhole.

Important: Always maintain a safe distance from the manholes. As the engine supervisor, safety of your members is your first priority as long as there’s no civilian life hazard. Treat underground transformer vault explosions the same as manhole fires and emergencies.

For Your Drill
When drilling on these types of emergencies, discuss the following points to make sure all members are aware of the dangers when operating at these types of incidents.
• Explosions are not uncommon at these types of incidents. They can occur at any time and are not necessarily located at the direct source of the fire. Many times, the condition seems to be alleviated and members get complacent. Explosions have occurred and may occur during these periods.
• Remain alert and maintain situational awareness, regardless of how routine the operation may seem. The conditions encountered may not reveal the dangers normally associated with fire and smoke.
• Identify possible areas where explosions may occur, and establish safety zones around these locations. These locations should be known by members operating at the scene as well as additional responding units. Members shall be under strict supervision to avoid accidentally entering these areas.
• Because these operations can sometimes be prolonged, incident commanders should ensure rehab procedures are in place to avoid crew exhaustion and complacency.
• To prevent civilians from entering the area’s danger zones, request law enforcement to respond. They can provide security around these zones, allowing firefighters to concentrate on the potential explosions and/or fire.
• Instruct the utility company to pull the affected manhole covers and continually monitor the danger zones. CO can travel to other manholes and vaults as well as poles housing traffic signals and the traffic control box. I’ve seen many utility workers injured and/or killed when it seemed the area was safe. During one incident in New York City, a manhole fire produced CO that traveled to a traffic control box. The CO accumulated and when the signal box transmitted the signal to change, an explosion occurred. Luckily, a safe area had been established and no one was hurt.
• Always wear full PPE when operating at these incidents, including SCBA, and wear it properly.

Lastly, expect the unexpected and always maintain situational awareness. Exercise caution at all times when operating near or in the vicinity of the manhole or underground transformer. CO can travel to unexpected places and explode at any time during the incident.

Remember: There are no “routine responses” anymore.

Chief Fred LaFemina is a 24-year veteran of the New York City Fire Department (FDNY), presently chief of Rescue Operations. He has been with Special Operations for more than 20 years and is the task force leader for New York’s Task Force 1 Urban Search and Rescue team. He is also the operations chief on the USAR IST White Team. LaFemina has written many articles on fire operations and technical rescue and lectures throughout the country.

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