Electrical fire origin & cause.

§1Scope of work

R-01 covers electrical-ignition investigations on residential, commercial, and light-industrial structures, on equipment installations within those structures, and on detached vehicles, marine craft, and outbuildings whose electrical systems are accessible to scene examination. Heavy-industrial substations and 600-V-and-above premises wiring fall under R-07 (transient origin) or R-06 (objectionable current) depending on the working hypothesis. The firm does not perform R-01 work on aircraft or rail equipment; those investigations are typically led by NTSB or FRA investigators with system-level access we do not possess.

A typical R-01 retainer is opened by an insurer or by litigation counsel within seventy-two hours of fire suppression. The retainer letter names the loss location, the insured, the date and approximate time of the call to the suppression authority, and any preserved evidence already segregated. The firm runs a conflict check against ten years of retained records before accepting the retainer; the check is final. If a conflict is identified — most often because the firm has worked the same defendant or insurer on a prior matter — the firm declines the retainer and provides a referral, typically to Envista Forensics or to one of two regional NAFE-credentialed firms with whom we have a long-standing referral relationship.

The investigative scope ends at the sealed report and any subsequent deposition and trial testimony required under the engagement. The firm does not write opinion letters for the insurer to forward to a third party without our knowledge; if the insurer wishes our findings communicated, we communicate them directly to the named recipient under the engagement’s identification.

§2Scene methodology

The scene visit is the foundation of every R-01 file. We arrive at the scene with the suppression authority’s release in hand and the structure still as it was at suppression to the maximum extent practicable. NFPA 921 §17–18 governs the sequence of documentation; we follow that sequence with the additions noted below.

The first photographic set is the eight cardinal-direction approach photographs at twenty-five feet from the structure (NFPA 921 §17.5.4), made before any debris is touched. The second set documents the exterior service entrance — meter base, service drop, service riser, weatherhead, mast head, ground rod and grounding electrode conductor, water-pipe bonding — with the meter base photographed both with the seal intact and (after the utility’s representative is on site and disconnect has occurred) with the cover removed. The third set documents the main switchboard or panelboard interior with the dead-front intact and with the dead-front removed. We do not pull breakers or remove conductors at this point; conductors stay in place for the arc-mapping phase that follows.

Arc-mapping per NFPA 921 §9.11 proceeds room by room, with each arced conductor segment photographed in-place, sketched onto a floor plan referenced to a permanent benchmark (typically a structural column or foundation corner), and tagged for retention. Sample retention is governed by ASTM E1188; samples are double-bagged in evidence sleeves, sealed with serialized tape, and signed across the seal by both the investigator and the suppression authority’s witness. The chain-of-custody form is opened at the scene and remains open through deposition or until the carrier authorizes destruction.

§3Exhibits & chain of custody

The firm’s evidence vault at Bay 4 is a fire-rated, environmentally-controlled cabinet on the rear wall of the bay, accessible only to PE-sealed engineers on the matter and to a single designated paralegal whose access is logged. Samples retained for a matter live in the vault under a Case File number; the vault holds the sample for ten years from the last filing or until the retaining carrier authorizes destruction, whichever comes first. The retention policy is documented at the Privacy page.

Photographic exhibits are stored in dual archives — a primary on a NAS in the bay and a mirrored offsite copy at a private storage facility in Millcreek Township. Both archives are SHA-256 hashed at the moment of retrieval from the camera and the hash is logged in the chain-of-custody record; tampering with an exhibit would be immediately visible at hash comparison.

Where a sample is sent to a third-party laboratory for analysis — typically Intertek for polymer-residue spectroscopy or to the ATF Fire Research Laboratory in Beltsville for ignition-resistant material testing — the chain-of-custody record is opened on transfer and the lab’s receipt is countersigned and appended to the matter file. We do not use laboratories that decline to sign chain-of-custody forms.

§4Hypothesis testing

NFPA 921 §4 imposes a hypothesis-test methodology on every fire investigation — the investigator develops one or more working hypotheses for origin and cause and tests each against the evidence rather than assuming a particular cause and seeking confirmation. Electrical-cause hypotheses, like all others, are tested against the totality of the evidence. The firm’s standing test grid runs through eight common electrical-ignition mechanisms in fixed order:

• H1 · Loose connection at termination point. Tested by examining suspect terminations for evidence of glowing-contact ignition (NFPA 921 §9.10.3) — degraded crystalline grain structure under the binder head, copper-oxide growth at the contact, parent-metal deformation. A loose connection in a junction box ahead of the suspected origin point is presumptive evidence; a tight termination ahead of the origin is presumptive evidence against H1.
• H2 · Series arcing through a degraded conductor. Tested by arc-mapping the suspect feeder and identifying multiple sites of melting consistent with series interruption (NFPA 921 §9.11.3).
• H3 · Parallel arcing across an insulation breach. Tested by examining for the characteristic localized arc bead consistent with line-to-ground or line-to-neutral arcing (NFPA 921 §9.11.2). AFCI breaker history, where present and recoverable, is examined.
• H4 · Overload heating of a conductor. Tested by computing the connected load at the time of fire and comparing to the conductor’s ampacity under NEC 310.16. Overload is uncommonly the cause; most reported overloads are misdiagnosed series-arc events.
• H5 · Surge-induced damage with delayed thermal runaway. Tested by checking Vaisala NLDN stroke data against the time window of the fire and by examining surge-protective devices for evidence of activation. Where R-07 work is warranted, the file is annotated for cross-protocol study.
• H6 · Failed appliance or attached load. Tested by isolating the suspect appliance and either re-energizing on a bench under exemplar conditions or comparing its remains to the manufacturer’s recall and field-failure history.
• H7 · Improper or non-listed extension cord or temporary wiring. Tested by examining for evidence of damaged insulation, undersized conductor, and operating environment inconsistent with the cord’s listing.
• H8 · Lightning strike. Tested under R-07 as a cross-protocol matter; see R-07.

A finding is filed only when one hypothesis is supported by the evidence and the remaining hypotheses are explicitly ruled out under NFPA 921 §4.3.6 (“negative corpus” reasoning is not used; the rule has been clear since the 2017 edition).

§5Worked examples

CF-2025-071 (the Mill Creek tube mill) is featured in this issue and reads in full at its dossier page. The fire occurred at 14:02:38 EDT on 9 February 2026; suppression was on scene at 14:09. The plant’s electricians had been reporting unbalanced phase currents on the 480 V secondary for approximately nine months prior; the clamp-meter records were preserved as exhibits in the Case File but had not been reviewed against the failed neutral until our investigation.

Two other worked examples from prior issues are useful illustrations: CF-2023-104 (a residential garage fire on East 38th Street traced to a non-listed extension cord powering a freezer in winter — H7 supported, H1 through H6 and H8 ruled out) and CF-2022-019 (a barn fire in Waterford traced to a series-arc event in a 20 A general-purpose branch circuit run through a hay-storage area — H2 supported with AFCI history recovered showing four trip events on the same circuit over the preceding twelve months).

§6Deliverable & fee

The deliverable on an R-01 file is a sealed PE report bearing the seal and signature of the principal investigator (typically Lindqvist-Vasilakou for fire-origin matters; Trzaska or Adekunle for matters involving distribution-system investigation). The report includes: a scope statement; the sequence of work performed; an exhibit list with chain-of-custody documentation; the hypothesis test grid; a finding; and a reference appendix. Where a finding is filed, the report is admissible without further engineering testimony at Daubert hearing in the federal and state courts within the firm’s area of licensure. Where no finding is filed (the evidence does not support any of the working hypotheses to the standard required by NFPA 921 §4), the report says so plainly.

The fee band for R-01 work is $12,500 to $48,000 per matter, billed against a retainer at $295/hour PE and $185/hour EIT, with a per-mile scene-visit charge consistent with the IRS standard mileage rate. The fee band reflects the cost of scene access, scene documentation time, sample analysis at outside laboratories where required, hypothesis testing, report preparation, and one scheduled deposition. Trial testimony is billed separately at a daily rate of $2,400 plus travel. The full schedule is published on the Engage page.

§7References