ReliabilityFirst recently published a report that details and analyzes the August 11, 2025 bulk power system disturbance that impacted approximately 4,000 customers in the Baltimore, Maryland, area for a duration of 28 minutes.
The disturbance stemmed from an unplanned outage at Baltimore Gas and Electric Company’s (BGE) Brandon Shores substation, located about 8 miles southeast of Baltimore, ReliabilityFirst said.
"The event, triggered by multiple failed contaminated insulators, led to the loss of the entire 230 kV substation, cutting off all transmission paths from the station to the grid in an already resource constrained area. As the situation progressed, BGE and PJM Interconnection responded using established escalating emergency procedures, including demand response, public conservation appeals, and voltage reduction to keep the system within safe operating limits," ReliabilityFirst said.
"Even with those measures, real-time engineering studies showed the potential of a cascading outage that could have impacted the entire city of Baltimore. Consequently, to ensure the transmission system stayed reliable and intact, PJM and BGE system operators shed approximately 20 MW of load, impacting 4,000 customers," ReliabilityFirst said.
While disruption of customer electric supply is never a desired outcome, the actions taken by PJM and BGE preserved the system’s integrity, it said.
ReliabilityFirst's analysis indicates that the manual load shed mitigated a potential uncontrolled loss of more than 1,500 MW of load in the Baltimore area. Since the event, BGE has replaced numerous insulators and increased equipment inspections.
ReliabilityFirst said its independent analysis showed that availability of local resources, including retired generation, would have helped to reduce the likelihood of load shedding during the event, despite transmission overloads, not resource shortfalls, driving the need to shed load.
The full report incorporates critical data and a sequence of events provided by the impacted entities and includes RF’s independent analysis, technical findings, and evaluation of the sequence of events.
ReliabilityFirst is one of six regional organizations which, in conjunction with the North American Electric Reliability Corporation, are known as the Electric Reliability Organization Enterprise, responsible for ensuring the reliability and security of the North American Bulk Electric System.
It promotes the reliability and security of the electric grid through standards, outreach, training and analysis, that includes partnership with communities and experts. Its footprint includes the Great Lakes and Mid-Atlantic areas of the United States.
