Lightning Damage
Lightning causes losses in the U.S. of over $5 billion per year. About 30% of the power outages are caused by lightning (worth over $1 billion). Lightning causes more than 26,000 fires with property damage per year. Roughly 5% of annual insurance claims (other than fires) are lightning-related, costing more than $1 billion. These include damage to TVs, recording and playing attachments, sound systems, alarm systems, appliances, air conditioners, and house wiring. Donan Engineering’s skilled forensic engineers have the training and experience needed to determine whether damage is the result of lightning or of some other cause.
What is lightning? It is a build-up and transfer of charges between clouds, between clouds and the ground, or between clouds and objects. Lightning is formed when a warm front and cold front converge. The rising and falling of moisture creates charges that build up and have to be discharged to adjacent clouds or objects on the ground. Lightning may carry several thousand volts in potential and several thousands of amperes of electrical current discharge for approximately 500 milliseconds.
Lightning is both beautiful and fascinating, but it is also dangerous. Globally, some 2,000 simultaneous thunderstorms cause about 100 lightning strikes to earth per second. In the U.S., lightning strikes occur on an average of four times per square kilometer. Florida, the lightning capital of the U.S., has the highest rate of occurrences at 15 to 30 strikes per square kilometer annually.
Recent engineering developments have included investigations into
Corrugated Stainless Steel Tubing (CSST), a flexible
gas piping system used for gas fuel distribution within both
single-family and multiple-family dwellings. This flexible gas piping
system is typically installed between the main gas line and the
manifold, as well as between the manifold and the various gas
appliances. Donan’s team of engineers and fire investigators is trained
to investigate structural fires caused by lightning which resulted in
several million dollars in damages.
Lightning will often strike the metal chimney caps and run down the metal flue system to the fabricated steel fireplace box. CSST is connected to either a gas log or log starter in the fireplace. The lightning discharges from the attached CSST to the first place it crosses a grounded metal object, including: metal furnace ducts, copper water lines, and Romex house wiring or conduit. Lightning penetrates into the CSST to form an arcing discharge, the ignition of the gas fuel, and/or a large flame that ignites adjacent combustibles.
The result of lightning discharge to Romex wire in the wall adjacent to a fireplace.
Donan’s team of engineers has been working to make changes to the building codes regarding the installation of CSST gas tubing. Indiana has adopted the requirement to separate CSST by a minimum of 2 inches from any grounded object such as metal piping, duct work, and wiring (conduit and Romex).
This type of damage to CSST can and generally does result in a significant fire, severely damaging or destroying a residence. If the fire is extinguished within the wall cavity (due to the lack of oxygen), it could later explode when it escaping from the cavity to attic spaces, spaces between floors, or crawlspaces.
