The Fire investigator must determine the potential for electrical involvement during all structural fire investigations. Most occupied residential or commercial buildings have energized electrical systems, which present many potential heat sources. Therefore, the investigator cannot simply ignore the “electrical fire cause” possibilities available during the fire investigation. However, identifying even the possibility of electrical involvement in the fire may be extremely difficult, depending on the extent of the fire damage.
Most fire investigators are not qualified electrical engineers. Although you may have a good basic understanding of the electrical system works, rendering a conclusive opinion on an “electrical cause” may jeopardize your case in court. However, in the elimination process used to identify the fire’s point of origin and probable cause, the investigator must constantly consider the electrical potential or be able to conclusively eliminate it in an energized structure.
In addition to the electrical fire cause potential, the fire investigator should always make sure that the building under investigation is de-energized prior to any physical examination. Failure to do so may seriously jeopardize the investigator’s personal safety.
The following checklist is designed to assist the investigator in determining if electricity was a contributing factor in causing the fire, and, if not, eliminating electricity as a fire cause. This checklist is not conclusive, nor does it eliminate the need for proper expert assistance; however, it offers the fire investigator with a series of essential checkpoints to use when examining the electrical system.
- Is the Building Energized? If not, the electrical system can be eliminated as a fire cause.
- Check the power pole to determine if power lines are supplied from the pole to the house.
- Is the electric service provided through underground wiring?
- Check the electrical masthead. Are the wires connected to the building? (From either underground or above-ground service?)
- Are the electrical wires connected from the masthead to the meter?
- Has the electrical meter been removed?
- Is there evidence of fire damage inside the meter housing? (Determine if the fire department or utility company disconnected the wiring or removed the meter after the fire was discovered.)
(Safety Note: Make sure that disconnecting the electric meter interrupts electrical service to the building. Inspect for a jumper wire.
- Check the Main Service Panel.
- Is the main panel breaker switch (fuse) on, off, or tripped? If off or tripped, did this condition occur before, during, or after the fire?
- Is there evidence of fire inside the panel box?
- Is there evidence of arcing visible inside the panel box?
- Are all circuits connected to the panel box? To breaker or fuse?
- Identify the type of overcurrent protection devices: Edison base plug fuses, “S” type plugs, Cartridge fuses, Circuit breakers, and Ground fault interrupters (GFI).
- What is the switch position of each circuit breaker: Open, Closed, or Tripped?
- What is the condition of the fuse: Screwed into the base, the fuse link is blown?
- Are fuses or circuit breakers rated adequately for conductor sizes?
- Are there signs of improper wiring within the panel?
- Are there signs of tampering with the service panel?
- Defeated fuses or breakers (conductors such as foil or coins behind fuse sockets, nails through cartridge fuses, jumper wires, tampering with breakers.)
- Check Building wiring.
- What is the wiring type: Copper, Aluminum, Combination?
- What is the condition of branch circuits: Fire involvement, signs of arcing?
- What is wire type? Non-metallic sheathed cable (Romex), armoured cable (BX), knob & tube, thin wall conduit, rigid steel conduit, plastic conduit?
- What is the condition of the wiring insulation?
- Are there short circuits? Where are they? Why?
- Are wiring connections inside appropriate junction/switch boxes?
- Check Junction Boxes.
- Is there evidence of fire inside the box?
- How is the wiring connected? Plastic wire nuts, twisted & taped, soldered, crimps, other?
- Are there loose splices or connections?
- Are improper wire sizes connected?
- Improperly rated outlets or switches?
- Improper aluminium to copper wire connectors?
- Defective outlets or switches?
- Bare or exposed wires?
- Dust, dirt or other foreign material in the junction box?
- Open knockout holes, not in use or covers missing?
- Worn connections?
- Electrical Equipment connected to the building’s electric system in the area of origin.
- Extension cords?
- Lamps or lighting equipment and connecting cords/plugs? (Lamp
- wattage?)
- Recessed lighting? (Was insulation in contact with recessed fixtures? Were recessed fixtures rated for direct insulation contact?)
- Electronic equipment (televisions, video recorders, stereo equipment, radios, recorders, telephone answering machines)?
- Personal computing equipment?
- Fax machines?
- Copy machines?
- Appliances (refrigerators, electric stoves/ovens, microwave, toaster ovens and other small kitchen appliances)?
- Electric heating equipment (furnaces, portable heaters)?
- Personal grooming equipment (hair dryers, curling irons, etc.)?
- Electric iron?
- Electric blankets?
- Heat tapes?
- Portable cellular phone and battery charging transformers?
- Electric tools and utility equipment?
- Doorbell transformer?
- Other electrical appliances or devices?
- Determine:
- Was electric wiring involved at the point of origin?
- Was any electrical equipment at the point of origin connected to the electric system?
- Was the electric equipment switch in the on/energized position?
- Was the electric equipment in use?
- Was the electric equipment connected to an extension cord?
- Were appliances connected to improperly rated extension cords?
- Was the electric equipment in an improper location?
- What is the electrical equipment’s type, brand name, model, and serial number?
- Was the fire confined to the wiring or electrical equipment?
- Is there evidence of heating or arcing in wiring or electrical equipment?
- Is there evidence of heating or arcing on metal parts not usually conducting electricity?
- Does the fire pattern indicate fire spread from wiring or electric equipment?
- Were there other non-electric heat sources at or near the area of origin, such as a fireplace, wood stove, kerosene heater, cooking, gas pilot lights, smoking materials, candles, or others?
- What was the material first ignited? An ordinary combustible such as wood, paper, drapes, clothes, trash, electrical insulation, etc. or a highly flammable vapour that an arc or spark could have ignited? (Were there any electrical devices (light switches, etc.) or equipment (motors, etc.) that could have provided an arc or spark?)
- Consider:
- Improper electric installation.
- Careless or improper use of electrical equipment.
- Amateur electric repairs.
- Intentionally caused electric fires.
An essential part of the fire investigation involves conducting detailed interviews with owners, occupants and other witnesses that may provide information about the fire’s origin and cause or conditions that may have contributed to the fire. The following questions should be included in the interview to determine whether or not there was electrical involvement in the fire:
- What type of electrical wiring or appliances were located in the identified area of origin?
- Was this equipment in use just before or at the time the fire started?
- Was any electrical equipment involved in the fire recently purchased and/or installed? (Details?)
- Who installed the equipment?
- Was electrical equipment overturned, knocked down, or damaged before the fire?
- Was the electrical service damaged in any way before the fire? (Details?)
- When was the building constructed?
- Who was the builder?
- Who wired the building originally?
- Have any electrical repairs or improvements been made recently? By whom? What type of repairs or improvements?
- Were there recent repairs to the electric service or appliances in the area of origin?
- Was the building energized before the fire?
- Have you noticed any electrical type problems or unusual occurrences?
- Fuses blowing or circuit breakers tripping frequently? (Details?)
- Any light or appliance switches operating improperly?
- Any light or appliance plugs loose, bent, or otherwise defective, causing the equipment to operate erratically when putting in or removing plug?
- Hot electric outlets?
- Television picture shrinking?
- Lights dimming?
- Static on the radio? (Excluding static caused by electric storms)
- Hot surfaces on the electrical product?
- Shock or tingling from electric appliances, devices, piping, etc.?
- Use of appliance causing fuses or breakers to trip?
- Was there an electric storm before or at the time of the fire discovery?
- Evidence of melted wiring or metals, isolated charring and exploded wood.
- Were there earthquakes, flooding, or other natural phenomenon before the fire?
- Were any high heat-producing appliances being used in the area of the fire, such as iron, curling iron, soldering iron, portable heater, dryer, stove, etc.?
- Were there any volatile liquids or gases being used before or at the time of the fire?
- Was there open flame used in the area, such as candles, fireplaces, wood stoves, smoking, and kerosene heaters?
- Personal observations of witnesses present before or at the time of the fire:
- Bright flash?
- Glowing?
- Small explosions?
- Light bulbs blowing?
- Crackling or popping?
- Other usual noises?
- Unfamiliar odours?
- Burning rubber or “hot” wiring smell?
- Smoke?
- Fire? (Where?)
Other Considerations for determining potential electrical involvement in the fire:
- In order to determine the cause, the investigator must accurately identify the fire’s origin.
- All potential heat sources or probable causes at the fire’s origin must be considered.
- Rule out all other possible causes.
- Determine all electrical possibilities.
- If the electrical situation is not energized, there will be no heat and no electrical fire.
- If the appliance or electrical device is unplugged, it can’t cause an electrical fire.
- If the suspect circuit is off prior to the fire, it didn’t cause the fire.
- The presence of an electric service or appliance at the fire’s origin does not necessarily prove it caused the fire. Determine “Why” the electrical problem caused the fire. Why did it fail?
- A fire caused by cooking on an electric appliance or placing combustible materials too close to an electric heating appliance is not an electrical fire.
- Remember, an intentionally set fire may be disguised as electrical.
- Electrical appliances and devices are used to set arson fires.
~by Kenneth M. Goodnight
