Abstract: At 4:30 a.m. on July 29, 2020, Employee #1, employed by Air Conditioning Solutions, Inc., was preparing for his shift at a commercial renovation site located at 101 Continental Blvd., El Segundo, CA. The employee, in basic work attire, went to a 460-volt breaker panel to power up a commercial welder hardwired to the panel. While flipping the breaker switch, an unexpected arc flash occurred, resulting in severe second- and third-degree burns to his forearms and hands. Emergency services transported him to Harbor UCLA Medical Center, where he was admitted for treatment. The incident's cause remains undetermined, with no violations noted due to lack of information and a non-violative condition.