Fire Technology

, Volume 54, Issue 4, pp 921–941 | Cite as

Pinched Cord and Overdriven Staple Failures: Research on the Causation of an Electrical Fire

  • Cameron Novak
  • Michael Keller
  • Theresa Meza
  • James McKinnies
  • Erik Espinosa
  • Kristie Calhoun


In the past, some fire investigators have determined the cause of a fire to be electrical in nature based, in part, on the presence of an electrical cord or cable found beneath a furniture leg or a cable wedged tightly under a staple. While fires resulting from these events are possible, the mechanisms that lead to these failures are poorly understood. In this paper, the results of four research projects are presented. The first three projects focused on the creation of a pinched cord failure under various current loads and pressures. In the last project, a typical nonmetallic-sheathed cable was damaged and then installed with an overdriven staple over the damaged location. In all tests, the cords and cables were subjected to current loads varying between 100 and 250% of the rated ampacity. The failure rate of pinched cords was approximately 1%, but required the use of overloaded circuits and pre-existing damage or special orientation of the cord under test. A critical factor worth considering with these failures, which is often not accounted for, is time. These failures may take weeks, months, or years to occur under normal conditions, although some investigators may assume they develop nearly instantaneously. The conditions of the circuit are also important, as the only way a failure developed in these tests was by operating the circuits in excess of their rated parameters.


Fire investigation Pinched cord Pinched cable Overdriven staple Electrical failure 



The authors would like to thank the support of the Bureau of Alcohol, Tobacco, Firearms, and Explosive’s (ATF) Fire Research Laboratory and the ATF Certified Fire Investigator program, both of which supplied money and resources to conduct this research. The authors would also like to thank James Zurenko, Steve Little Jr., Dennys Hernandez, RJ Markward, Matt Rimland, and Joe Bettenhausen, whose assistance was instrumental in the completion of this research. Hopefully the many pinched fingers have healed!


  1. 1.
    United States Fire Administration (2017) Fire estimate summary—residential building fire trends (2006–2015). Accessed 4 Oct 2017
  2. 2.
    NFPA 921: guide for fire & explosion investigations. National Fire Protection Association, Quincy, MA (2017)Google Scholar
  3. 3.
    DeHaan J, Icove D (2012) Kirk’s fire investigation, 7th ed. Pearson, Upper Saddle RiverGoogle Scholar
  4. 4.
    Babrauskas V (2003) Ignition handbook: principles and applications to fire safety engineering, fire investigation, risk management and forensic science. Fire Science Publishers, Issaquah, WAGoogle Scholar
  5. 5.
    Dini D (2008) Residential electrical system aging research project (report). Underwriters LaboratoriesGoogle Scholar
  6. 6.
    He F, Brazis Jr. P, Chen L (2011) Assessment of NM cable to resist arc conditions (presentation). Underwriters LaboratoriesGoogle Scholar
  7. 7.
    He F, Brazis Jr. P (2011) Assessment of NM cable installation damage (presentation). Underwriters LaboratoriesGoogle Scholar
  8. 8.
    He F, Brazis Jr. P (2013) Influence of damage and degradation on breakdown voltage of nm cables (report). Underwriters LaboratoriesGoogle Scholar
  9. 9.
    Babrauskas V (2005) Mechanisms and modes for ignition of low-voltage PVC wires, cables, and cords. In: Fire and materials 2005. Interscience Communications Ltd., pp 291–309Google Scholar
  10. 10.
    Babrauskas V (2014) Fires originating in branch-circuit nm cables due to installation damage. In: International symposium on fire investigation science and technology. National Association of Fire Investigators, pp 32–43Google Scholar
  11. 11.
    Ettling B (1994) The overdriven staple as a fire cause. In: Fire and arson investigator. International Association of Arson Investigators, pp 51–53Google Scholar
  12. 12.
  13. 13.
  14. 14.
    Beyler C, Gratkowski M (2006) Low-voltage (14 VAC) electrical circuit fire initiation. In: International symposium on fire investigation science and technology. National Association of Fire Investigators, pp 519–527Google Scholar
  15. 15.
    Romex SIMpull Type NM-B product page.
  16. 16.
    Data Bulletin: Circuit Breaker Characteristic Trip Curves and Coordination (Schneider Electric Bulletin No. 0600DB0105). Cedar Rapids, IA (2001)Google Scholar

Copyright information

© This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply 2018

Authors and Affiliations

  1. 1.ATF-Fire Research LaboratoryBureau of Alcohol, Tobacco, Firearms, and Explosives (ATF)BeltsvilleUSA
  2. 2.School of Forensic SciencesOklahoma State UniversityStillwaterUSA
  3. 3.Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF)ShreveportUSA
  4. 4.Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF)BaltimoreUSA
  5. 5.Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF)MiamiUSA
  6. 6.Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF)JacksonvilleUSA

Personalised recommendations