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“Learn the step-by-step process of doing an Arc-Flash injury investigation as an engineering expert”

By John D. Gaskell, Retired Consulting Engineer

Author of “The Complete Guide to FORENSIC ENGINEERING

Forensic engineering is defined by the National Academy of Forensic Engineers (NAFE) as “the application of the art and science of engineering in matters which are in, or may possibly relate to, the jurisprudence system, inclusive of alternative dispute resolution.” These engineers serve as consultants to the legal profession and as expert witnesses in courts of law.

Acceptance of Cases

Accept only cases in your field of expertise, but don’t necessarily limit them to your area of specialty. My cases as an electrical engineer included electrocutions, fires of suspected electrical origin, standard of care determinations, equipment failures, arc fault accidents, conveyor accidents, lightning strikes, and others. Yours will be different but also interesting and challenging.


The following is a narrative synopses of one of my cases. This is not intended to be a formal presentation of legal actions. No confidential or privileged information is revealed. This is simply my recollection, intended only to illustrate an expert’s typical involvement in judicial matters.

I was the chief investigator and expert witness on all of the forensic cases of Gaskell Associates, Ltd., and later those of the Gaskell Associates division of Thielsch Engineering, until my retirement. However, it was my practice to meet on each case with my senior staff to “brainstorm” the case. This often opened up avenues of investigation that had not previously occurred to me. I attribute much of my success to hiring others who are smarter than I am.

Case Study – Arc Flash Injury

This arc – flash accident occurred when two electricians were troubleshooting an inoperative fan motor. They discovered a blown fuse in a 480-volt motor control center (a freestanding enclosure containing both fused switches and motor starters). They installed new fuses, closed the compartment door, tightened the screws holding the door, and closed the switch. An arc fault occurred in the compartment, which blew the door off, injuring both electricians and creates an arc – flash. One had his clothes catch on fire resulting in third degree burns over 50% of his body. Both electricians were covered by “workman’s compensation insurance,” so they could not sue their employer for this arc – flash . The more severely injured man sued the manufacturer of the motor control center. We were hired by his attorney to investigate.

First, we spent a lot of time looking through two big boxes of paperwork including information obtained from the manufacturer of the motor control center. Next, we did online research on the switchgear manufacturer’s website and on the website of Underwriters Laboratory (UL). Then, we visited the site, examined the switchgear, and interviewed both electricians.

We observed that the spacing of the bus bars (live parts) within the enclosure appeared to be minimal and later compared this spacing to the details of other manufacturers of the same type of equipment, which confirmed our observation. We found numerous testing reports of the model switch at issue, and all ended in failures. We could not find any reports of arc – flash, but also no reports of switches that passed. However, we did find a letter from UL saying that the motor control center had qualified for “Follow up Services” which is a term used when equipment has passed initial testing and now can be manufactured with a UL listing and is subject to occasional inspections by UL. The UL Follow-Up Service program is designed to monitor the processes that a manufacturer uses to produce products in compliance with certification requirements. UL’s field representatives make periodic tests and/or examinations at the factory, and may select samples from the factory, the open market or elsewhere for further determination of compliance. In addition, if a problem with a UL certified or classified product is reported to UL, UL will investigate these situations thoroughly.

Our “very happy” attorney/client called us two weeks later to tell us the case had settled, based on our research. You don’t necessarily need to testify to provide a valuable service.

Litigation consulting is interesting, challenging, and profitable. If what is involved interests you, I recommend adding “Forensic Engineering” to your practice as a consulting engineer.

Get Jack’s new book: The “Complete Guide” to FORENSIC ENGINEERING to learn the details. Also, the largest chapter in his book: The “Complete Guide” to CONSULTING ENGINEERING covers the “highlights” of Forensic Engineering. Visit to find out more.

Learn how to be a forensic engineer. Learn how to be a forensic expert witness. How to be an engineering expert witness. How to obtain training as a forensic engineer. How to obtain training as an engineering expert witness.