Forensic Engineers and Consultants

Tag Archive: electrical loss

  1. In a Flash – The Transfer of Energies in Our Global Electrical System

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    According to published weather data for the year 2019, 2.35 billion lightning strikes were recorded across the world, with 223 million of these in the United States.  The movement of atmosphere causes electrical charges to build up between clouds.  A tipping point is reached where the insulating properties of the air cannot withstand the level of energy and a discharge occurs.

    Image Credit: Charleston Post and Courier. A lightning strike over Charleston, SC on July 3, 2019.

    Such discharge is rapid, lasting between a fraction of a second to just a few seconds.  With voltages between 40kV to 120kV and currents from 5kA to 200kA, each discharge can transfer up to 10 billion watts of power.  Such large bursts of energy can cause significant physical damage to structures and people.  The sudden expansion of moisture in a tree can cause it to be ripped apart and pieces thrown a significant distance from the base.   Wires can be melted as the energy is conducted to the ground reference of the earth.

    Using technology that came out of detecting nuclear weapon discharges, lightning is tracked around the globe.  Distributed sensor networks measure the intensity of lightning strikes and triangulate the precise locations.  This information is collected and made available to support the investigation of lightning claims.

    Nearby, non-direct lightning strikes can also cause damage.  Significantly high voltages can be induced through the soil to cause damage to electrical components nearby.  A good example of this situation is an inground well pump.  The high voltages induced can degrade insulating materials on conductors that in turn can cause an electrical failure.  The electrical properties of wiring can be tested to determine if lightning is a cause of a failed device.

    Protecting against lightning can be difficult and costly.  Lightning protection systems can be designed and implemented to help mitigate the effects of a lightning strike to a structure.  The National Fire Protection Association (NFPA) Standard 780 is a standard that guides the selection and installation of lightning protection systems (LPS).  Annex L of the NFPA 780 standard describes a method of performing a risk assessment to determine if a structure would significantly benefit from an LPS.  Factors in the assessment include physical properties about the structure, terrain considerations, geographic location, and neighboring structures.

    The selection and installation of surge protection devices is another means of reducing damages from the power of lightning.  These devices will be discussed in detail in an upcoming blog.

    Tom Kelly has a Bachelor of Science in Electrical Engineering and a Master of Science in Electrical Engineering from Florida Atlantic University, Boca Raton, Florida, along with a Master of Business Administration with emphasis in strategic leadership from Winthrop University, Rock Hill, South Carolina. Tom’s 30 plus year career in electrical engineering includes forensic engineering investigations involving industrial electrical accidents, electrical equipment failure analysis, control system failures, robotics and automation components, and scope of damage assessments.  He has conducted investigations for fires, arc flash incidents, electrocution and electric shock accidents and lightning strike evaluations.

  2. Congratulations Tom Kelly on CESCP Certification!

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    Congratulations to Tom Kelly for completing his Certified Electrical Safety Compliance Professional designation. The National Fire Protection Agency (NFPA) program, CESCP, is designed to meet the needs of electrical and safety professionals who oversee electrical safety programs or who manage electricians and other personnel exposed to electrical hazards.

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  3. The Demise of Insulation on Electrical Wiring

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    Unlike fine wines and some types of cheeses, not everything ages well.  Such is the case with the materials used as insulation of electrical wiring.  While the copper metal used as the conductor in many wire types will last virtually forever, the cladding used to protect and insulate the wire allowing electrons to flow to their final destination does not. (more…)

  4. Hidden Heat: The Unseen Hazard of a High Resistance Connection

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    A typical residence can have upwards of 10,000 feet of electrical conductors installed, most of which are buried in the walls, attics and crawlspaces.  A commercial building can have 100,000 to upwards of 1 million feet of electrical conductors.  At each device such as a switch or a receptacle are at least three, and typically six or more connections of these conductors within a junction box.  The connections can be in the form of twisted connectors, screw terminals, push in terminals and crimped connectors.

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  5. Testing…testing… Is this thing on?

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    Many people just take for granted that something is just going to work, and in many cases assume that it will work forever.  One such device that does not get enough attention is the Ground Fault Circuit Interrupter (GFCI).   Simply put, a GFCI is a protective device that compares the current flowing on the hot and neutral wires of the circuit and will “trip” to disconnect power to the circuit if a small imbalance of current is detected.  The imbalance of current is an indication of a dangerous alternate path for the current to flow from a damaged line cord or a fault inside an appliance and constitutes a shock hazard to a person. (more…)

  6. Ready, Set, Fly! – Understanding Another Technology for Forensic Investigations

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    This is the first blog in a series on integrating new technologies into the process of forensic investigations.  Documenting the scene of an incident accurately, efficiently, and safely is a key step in every investigation.  Busy roadways and unstable structures present hazards to the investigator during the investigation process. The use of remote sensors can reduce these risks and provide data that otherwise could not safely be obtained. (more…)

  7. Grounding versus Bonding – Understanding the Difference in Building Electrical Systems

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    While a teenager might be very familiar with being “grounded”, there is confusion over the meaning of the word in the electrical sense. In building electrical systems, “grounding” and “bonding” are two terms that are often misunderstood. Improper application of the concepts of grounding and bonding may create lethal shock and fire hazards. “Earthing” is a term which comes from the European International Electrotechnical Committee (IEC). Earthing is synonymous with grounding but often thought to have a different meaning. (more…)

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