10 Indicators of an Electrical Infrastructure Fire

By Chris Greene and Mark Cox

Electrical infrastructures, for the purpose of this article, are infrastructures that require voltages greater than 600V service. For further clarification, high voltage is anything over 600V.  These voltage delineations are important to properly understand the electrical hazards all around us. 

For example, service for a typical single-family R-3 (R-3 is a classification of building construction identified by the United Building Code as a “Single Family Residential” structure; this includes town homes of less than three units) is 120V. Single-family residences do not require “high voltage,” as current demand is low and predictable. On the other hand, electrical service for an apartment building or high-rise office building often exceed 12,400V. As you can see, the jump from a single-family R-3 to a commercial structure is tremendous. There is no middle ground. You are generally dealing with sub 600V or above 12,400 volts when it comes to typical metropolitan service voltage requirements.

Electrical infrastructure hazards are high-voltage hazards and require the most earnest level of respect.  These incidents need to be identified early and communicated to on scene resources: “Units on scene from Command, be advised, this is an electrical infrastructure hazard.” This communication alone should tell everyone that the electrical hazard is extreme, and advancing on this hazard will likely exceed your training and personal protective gear. In these situations, your ability to quickly read the signs of electrical infrastructure involvement will be critical. Here are a couple of tips that will help you identify this unique hazard quickly and result in a more robust risk assessment.


  1. There is smoke from a door marked “High Voltage,” “Vault Room,” or Manhole.” This goes without saying.
  2. Power loss to a large building and an alarm indicating the initial detector is in the basement are clear signs that this is infrastructure. This is due to the primary electrical service entering from underground and accessing the building through a vault or manhole space in the garage/basement.
  3. Illuminated egress lighting tells you that the building has lost its primary electrical power.  Whether the issue is in the building vault or the street vault, it is infrastructure that is the cause for power loss.
  4. Smoke from a basement door with power loss in the building and egress lights illuminated is literally “the Lindbergh baby holding the Hope diamond.” This is one of the clearest indicators that what lies behind the door is high-voltage electricity.
  5. Limited power loss to a building (intermittent floors) with elevators disabled is a telling sign that the electrical infrastructure has faulted.
  6. Odor of ballast with power loss to the building is not ballast. Odor of ballast and odor of electrical are completely different.
  7. An active manhole/vault fire in the street near a building fire response. These two should be considered connected until proven otherwise. Complicating this situation is that they may receive different/parallel fire responses. The presence of a manhole fire near a building fire response address needs to be communicated to the dispatchers as well as responding units for both responses.
  8. Reports of explosion sounds in the building followed by power loss and/or signs of power loss
  9. Fire or smoke involving the switchgear room/space. While switchgear does not generally require voltages above 600V, these rooms contain all the electrical current/amperage needed for the building and will provide direct access to the electrical vault space.
  10. Power loss to a building accompanied by elevated carbon monoxide (CO) readings in the building. An active street vault fire may also cause this, as the CO is pressed into the building through electrical feeder conduit.

It is important to note that these represent some of the most obvious indicators of infrastructure involvement, with the loss of power being tied to many of them. Consider them infrequent and high-hazard incidents. Resolving these incidents effectively and safely will most certainly involve early recognition and coordination with your electrical energy provider. 

Chris Greene is a captain and the Energy Response Team supervisor for theSeattle (WA) Fire Department.

Mark Cox is a firefighter and an eight-year veteran of the Seattle (WA) Fire Department.

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