Authorities say the incident happened at about 10:45 a.m. in the 900 block of North Lake Avenue.
Street closures and evacuations were ordered for the immediate area surrounding North Lake Avenue and Mountain Street.
Officials say about 800 commercial and residential customers were affected by the power outage.
Vault fire update: power restored with exception of 955 N. Lake Ave. where incident occurred. Evacuations lifted. Fire units are clearing.— Pasadena Fire Dept. (@PasadenaFD) April 14, 2015
Power was restored to most customers by 1:20 p.m., and evacuations were lifted.
Crews from Pasadena Water and Power were investigating the incident.