ATC identifies cause of MGE blast

The explosion of Madison Gas and Electric’s 138-kilovolt transformer in downtown Madison was caused by a rare mechanical failure, according to media reports.

American Transmission Co., which inspected the parts, found a faulty 35-year-old voltage regulator to blame, a rare occurrence since most last between 50 or 60 years. Nevertheless, ATC had visited the site several times before the substation blast and was planning to shut the transformer down for a more detailed inspection on July 22. The explosion occurred the morning of July 19 on what turned out to be the hottest day of the year, causing power outages to about 13,000 homes and businesses.

Amazingly, no injuries were reported and almost all of the power was restored by the end of the day.