Arc Flash and Lightning Damage in UPS Systems

Years ago, at the Arizona Republic and Gazette newspaper, a catastrophic event unfolded inside their critical power infrastructure. A massive 500 kVA GE uninterruptible power supply (UPS) had suffered a severe malfunction after a lightning strike rippled through the system.

When our team arrived on-site, the damage told the story before a single panel was opened. Inside the inverter and UPS assembly, arc flash scarring was everywhere—evidence of the immense energy unleashed. Molten metal and blown-off bolts littered the cabinet. Copper bus bars were warped, scorched, and in some places completely disintegrated. Several IGBT transistors were fused and shorted beyond recognition, and other components had literally vaporized under the violent surge.

The damage was so extensive that repair was not an option. The only resolution was a total and complete replacement of the UPS system.

Despite an “Act of God” clause in our service agreement, we honored our commitment and replaced the unit under contract at no charge to the customer.

This incident stands as a stark reminder of how arc flash and lightning damage can utterly destroy high-capacity UPS systems, endangering both equipment and facility operations. It also underscores the importance of
awareness, training, and preventive measures when working around critical power systems—because when lightning strikes and arc flash ignites, the consequences are absolute.