John H. Diggle, III

Principal Consultant / PE, CFEI / Chicago


Mr. Diggle received his Bachelor of Science degree in Electrical Engineering from Cedarville University. During his professional career, he has participated in more than 500 forensic investigations. He has extensive experience in the inspection of electrical systems and appliances for the purpose of analyzing and evaluating potential electrical failure scenarios. He has provided technical assistance as well as expert opinions and testimony on matters involving residential, commercial, and industrial building fires, as well as vehicle fires, lightning damage, electrocutions and arc flashes. He is proficient in electrical equipment grounding and consumer products failure analysis.

Mr. Diggle has also provided electrical design services for projects including the renovation of a 13-story residential building, the installation of a public high-school athletic field complex and the renovation of a retirement-home facility. He has taught the electrical section of the "Fire and Arson Investigation" course for the University of Illinois Fire Service Institute.

Mr. Diggle is a Certified Fire and Explosion Investigator (CFEI) and is a licensed Professional Engineer (PE) in multiple states.

Representative Engagements

  • Fire investigations involving electrical systems and components include
    • Industrial complexes
    • Residential and commercial buildings
    • Land and marine vehicles
    • Consumer appliances
  • Electric shock and electrocution investigations
  • Electrical arc-flash and explosion investigations
  • Lightning damage claims
  • Utility power surge damage claims
  • Electrical failures in industrial machines
  • Investigation of electrical manufacturing and design defects
  • Electrical bonding and grounding issues
  • Electrical safety of consumer products
  • Determining compliance with codes and standards


  • B.S Electrical Engineering - Cedarville University, OH