Lightning & surge event investigations.

§1Scope of work

R-07 retainers arrive in two patterns. The first is a post-event claim — equipment has failed, the customer attributes the failure to a lightning strike or switching surge, and the insurer or counsel needs a sealed engineering finding on whether a strike or surge of sufficient magnitude can be documented to have occurred at the relevant time. The second is a pre-event audit — a facility’s lightning-protection system (NFPA 780 compliant or otherwise) needs to be evaluated for adequacy, typically after a near-miss incident.

The Lake Erie corridor is one of the more lightning-active regions in the upper Midwest; the National Weather Service Cleveland office reports 18 to 24 thunderstorm days per year for Erie County, with summer-evening storms moving east across the lake and concentrating activity in the Erie–Cleveland–Buffalo corridor. The firm has filed 64 R-07 matters since 2014.

R-07 cross-references R-06 (grounding/bonding) on virtually every matter — a lightning strike on a building with a degraded grounding electrode system produces dramatically different equipment damage than the same strike on a properly bonded system. The two files are routinely opened together.

§2Stroke data & correlation

The firm maintains a commercial subscription to the Vaisala National Lightning Detection Network, which provides geocoded stroke records (latitude, longitude, time to millisecond resolution, polarity, peak current estimate, and multiplicity for the flash) for the contiguous United States. For each R-07 matter we extract all NLDN strokes within a defined radius of the loss location and within a defined time window of the loss event. The default is 8 km radius and ±20 minutes; this is generous and is tightened where the evidence supports a more precise window.

A direct strike at the loss location requires a stroke within the building’s effective collection area as defined by IEC 62305-2 rolling-sphere analysis — typically within 30 m of any conductive part of the structure. Cloud-to-ground strikes at 30 m and beyond produce induced surges on power and signal cables; the magnitude scales with distance and with the configuration of nearby conductors. Within 100 m, a 10 kA stroke can readily induce a 6 kV / 3 kA surge on a 200 m branch circuit run in metal raceway; without the raceway shielding the induced surge can be substantially larger.

Where the NLDN search returns no stroke within the relevant radius and window, the “direct lightning” hypothesis is ruled out and the investigation turns to switching-surge sources — utility-side reclosing, capacitor switching, large-motor starting, transformer inrush. These are characterized under IEEE C62.41.1-2024 location categories and can frequently be confirmed against utility SCADA records.

§3SPD forensics

Surge-protective devices on the facility’s service entrance, sub-panels, and at sensitive equipment are examined for evidence of operation. UL 1449 SPDs include indicator LEDs or mechanical flags that report end-of-life or trip status; we record the state of every SPD on the premises. Where SPDs are present and operated, they are retained as exhibits and may be sectioned at Intertek’s electrical lab for internal-component analysis. The MOV stack’s clamping voltage is read from the device’s nameplate against the surge waveform the device experienced; an undersized SPD on a service that experienced a 20 kA surge will have failed catastrophically while a properly-sized SPD will have operated cleanly and reset.

UL 1449 5th edition (2017) introduced explicit guidance on Voltage Protection Rating (VPR), Nominal Discharge Current (I_n), and Maximum Continuous Operating Voltage (MCOV). Devices installed under UL 1449 3rd edition or earlier are noted in the report but not flagged as deficient absent a specific finding; many of those devices are still serviceable.

§4Deliverable & fee

The R-07 deliverable is a sealed PE report with: scope; NLDN stroke search and map; loss-event correlation; equipment-damage catalog; SPD forensic report; finding on whether a lightning strike or switching surge of sufficient magnitude can be documented to have caused the failure. Fee band $7,500 to $26,000.

§5References