The Las Vegas fire department and NV Energy crews responded quickly, but it took approximately 90 minutes for the fire to burn itself out. Fortunately, no one was injured. Thanks to a carefully coordinated effort between NV Energy’s transmission and distribution operations, as well as crews on site, the major distribution feeders were reenergized within a few hours. Later that Sunday morning, all customers were back in service.
In spite of the initial explosion and sustained oil-fed fire, both firewalls that bookended the autotransformer were remarkably intact. More importantly, the GIS equipment located behind the firewalls was protected from the heat and explosion. It was not damaged and remained available for service. The autotransformer was a total loss, naturally.
This event illustrates the modular firewall system worked well and literally acted as the last line of defense. It prevented a very expensive and lengthy substation rebuilding effort.