Fire Investigation Guide: Electrical and Forensic Fires

A fire investigation finds where a fire started (its origin) and what caused it. When wiring, a device or an appliance could be the ignition source, an electrical engineer examines that evidence alongside the fire investigator. This fire investigation guide is for insurance adjusters, subrogation counsel, attorneys, property owners and engineers who want to understand how origin and cause are determined, what electrical evidence can and cannot show, and what to do in the first days after a loss.

The articles below are the ones we would give a new colleague, in the order we would give them. Each section also links the interactive explainer that fits, and the service page for that part of the work if you would rather talk to an engineer.

1. Start with the basics

• The fire investigation process: Start here. It walks through evaluating, documenting and processing a scene, and how origin and cause are determined systematically.
• Fire dynamics in fire investigation: How fires ignite, grow and spread, and how heat transfer shapes the patterns investigators read.
• What a forensic engineer does: How forensic engineers investigate failures and fires, and when to bring one in.
• Arson investigator vs. fire investigator: The difference between the two roles and how they work together.

To see how we approach residential, commercial, industrial and vehicle fires, visit the fire and explosion investigation page, which also explains how evidence is documented and preserved.

2. How the electrical evidence is assessed

• Arcing vs. melting damage: How to tell arcing damage from melting damage on conductors, and what each one says about the fire.
• Myths about arc mapping: Common misconceptions about what arc beads, arc direction and arcs inside appliances can tell you about the origin.
• Loose connections and fire: How a loose connection heats up and starts a fire, and what investigators look for afterward.
• Appliance fires: X-ray and thermal imaging: How forensic X-ray and thermal imaging help find the root cause of an appliance fire without destroying evidence.
• Thermal transient analysis after a fire: How the way heat moved through an electrical enclosure during a fire is used in a post-fire inspection.
• Electrical failure analysis: The common failure types behind outages, equipment damage and fires, and how engineers trace them to a root cause.
• The scientific method, step by step (interactive): The NFPA 921 method from recognizing the need to the report, and the path a piece of evidence takes from the scene to the lab.
• Line up the clocks (interactive): Put four records of one night on one time axis, correct the clocks that drift, and see the order of events.

When the question is whether wiring, a connection or an appliance started the fire, see electrical fire investigation.

The matching services are forensic electrical engineering, residential electrical fire investigation, commercial fire investigation and appliance failure investigation.

3. Method, standards and testimony

• Minimizing cognitive bias: How the NFPA 921 method, complete data collection and testing every hypothesis keep a report objective.
• Frye vs. Daubert: How courts decide whether expert testimony is admissible, and what that means for the way an investigation is documented.
• Choosing a forensic engineering consultant: What to check before you retain an expert: the services that match your loss, the firm and the credentials.

If your file needs an expert witness, our forensic engineering services page lists the disciplines we cover. Before you assign it, request our CVs.

4. The scene and the evidence

• Fire scene evidence preservation checklist: A step-by-step checklist for insurers and attorneys, from securing the scene and notifying interested parties to the joint lab examination.
• What to do after an electrical fire: Safety first, what not to touch, and when to call your insurer and an investigation team.
• Fire investigation tools and techniques: Portable GC/MS, 3D laser scanning and arc mapping, and where each one helps.
• Drones in fire investigations: How drones help document a scene, from mapping burn patterns from above to finding hot spots.

Evidence goes to our engineering lab, where engineering X-ray services let us look inside a part before it is taken apart, and 3D space capture records the scene as it was found.

5. Common causes of electrical fires

• Common causes of electrical fires: Wiring, outlets and overloading, extension cords, appliances and space heaters, with the warning signs to watch for.
• Commercial electrical fire causes: Faulty wiring, overloaded circuits and arcing in commercial buildings, and the prevention steps that work.
• Dryer fires: What causes them, the warning signs and what to do after one.
• Common causes of car fires: From electrical faults to fuel leaks, and how they are prevented.

For vehicles and heavy equipment, see our vehicle fire investigation page.

How Dreiym Engineering Can Help

We investigate residential, commercial, industrial and vehicle fires for insurers, adjusters, attorneys and property owners, with licensed Professional Engineers examining the electrical evidence. Brian J. Brackensick, M.S., P.E. and Stepan V. Eero, M.S., P.E. both hold the NAFI CFEI and CVFI certifications. Our engineering lab in Coldspring, Texas has in-house real-time X-ray, and evidence storage is video-monitored. We schedule scene inspections as soon as possible after we are retained, we accept consulting-only retentions, and reports are PE-stamped where required. To start an assignment, use our forensic assignment form. Contact us or call (866) 621-6920 for a free quote. We typically respond within one business day.