After the Fire

If you haven’t been made aware of the fact that electrical equipment exposed to water can be extremely hazardous if re-energized without proper reconditioning or replacement, then you just may also be surprised to hear that a similar message is applicable to electrical equipment exposed to the smoke/soot that may result from burning materials during and after a structure fire. One could argue that a structure fire not only creates an environment that is hazardous to the health of the occupants and first responders, it also has the ability to create a hazardous location caustic to electrical equipment.

As electrical professionals who provide a service to our customers, it is important that we make the right decisions for safety when reviewing electrical equipment located in structures that have experienced fire and/or smoke damage. In addition to your years of experience and training on how to appropriately apply electrical equipment, a resource is available from the National Electrical Manufacturers Association (NEMA) to help make correct decisions with this regard. A recently published NEMA document titled “Evaluating Fire- and Heat-Damaged Electrical Equipment” may be helpful when reviewing electrical equipment in structures that have experienced fire and/or smoke damage. In addition to this NEMA resource, product standards and the National Electrical Code® (NEC) are important during this process as well. The activities that occur after a structure experiences fire, or even just smoke damage, is important for a safe electrical installation. You don’t have to make important decisions alone.

Releasing Chemicals

To understand the caustic environment created by a fire, just look around at the inventory of items in a structure that may ignite and become fuel. There are plastics, wood, various fabrics, glue, electronic equipment, fiberglass, and much more. When materials burn, they experience a chemical change where the elements that make up the materials change state: Some remaining a solid, some taking the form of a liquid, and others take the form of a gas. Materials that burn are considered fuel and when a fuel burns four products of combustion are experienced: Fire gases, flame, heat, and smoke.

The vapors released during a fire have the most ability to extend far beyond the direct location of the fire. This would include fire gases and smoke. Some of the gases released during a fire will rise and others have a tendency to hug the ground, and all of them can be carried by wind or other reasons for air flow. These gases can leave a residue on everything it engulfs. Residue on electrical equipment, especially energized parts, can be quite hazardous.

Structure fires can release large amounts of smoke. Even the smallest of fires, depending on the fuel, can produce a large amount of smoke. Merriam Webster defines smoke as “the gaseous products of burning materials especially of organic origin made visible by the presence of small particles of carbon.”

A fire can release many chemicals toxic if inhaled. They include the following:

  • Carbon monoxide – Produced from organic materials
  • Hydrogen cyanide – Originating from polyurethane, wool, silk, and paper
  • Acrolein (aldehydes) – Result of burning wood, acrylics, cotton, and rubber
  • Nitrogen Dioxide – From cellulose and wood
  • Ammonia – Common due to burning nylon, wood, silk, and polyurethane
  • Hydrogen chloride – Polyvinyl chloride (PVC pipes) and upholstery
  • Hydrogen fluoride – Teflon
  • Hydrogen bromide – Fire retardants
  • Sulfur dioxide – Rubber
  • Isocyanates – Polyurethane, wool, silk, and paper
  • Acrylonitrites – Polyurethane, wool, silk, and paper
  • Hydrogen sulfide – Wool, silk, and rubber
  • Benzene – Petroleum-based plastics
  • Styrene – Polystyrene
  • Phsogene – Polyvinyl chloride (PVC)
The bottom line is that smoke is v