USA, California, San Francisco: A new report has revealed that the PG&E substation fire which caused major power outages across San Francisco in December was likely triggered by a mix of humidity, condensation and equipment problems.
The fire broke out on 20 December at the Mission Street substation in SoMa, leaving around one third of the city without electricity at the height of the disruption. Some homes and businesses remained without power for several days during the busy holiday period.
PG&E released findings from a report carried out by third-party firm Exponent. Investigators concluded that unusual weather conditions allowed humidity to collect inside the mostly enclosed substation, which also uses open ventilation to cool equipment.
According to the report, condensation formed on an insulating board and later came into contact with a power switch. This caused electricity to move incorrectly, creating an explosive electrical burst that started the fire.
Sumeet Singh, chief executive of PG&E’s operating subsidiary, compared the situation to a leaking roof in a well-maintained home, where difficult weather conditions and normal wear combine unexpectedly.
Exponent said the problem developed after a long cool spell was followed by rapid warming, creating conditions for condensation to build.
PG&E said it has already added humidity controls and weatherproofing at all 16 indoor substations in San Francisco. The company has also carried out inspections, accelerated maintenance work and introduced extra monitoring systems.
State regulators at the California Public Utilities Commission are still investigating the incident.
Source: MSN
