MEC&F Expert Engineers : CABLE SHORT CIRCUITING LEADS TO UNDERGROUND EXPLOSION, FIRE IN LYNN, MASSACHUSETTS. EXPECT A SIGNIFICANT INCREASE IN MANHOLE FIRES DUE TO THE AMOUNT OF SALTS USED TO MELT THE ICE/SNOW THIS HARSH WINTER

Monday, March 16, 2015

CABLE SHORT CIRCUITING LEADS TO UNDERGROUND EXPLOSION, FIRE IN LYNN, MASSACHUSETTS. EXPECT A SIGNIFICANT INCREASE IN MANHOLE FIRES DUE TO THE AMOUNT OF SALTS USED TO MELT THE ICE/SNOW THIS HARSH WINTER




















MARCH 16, 2015

LYNN, MASSACHUSETTS

Officials said a short circuit in an underground vault caused a minor explosion and a fire beneath the sidewalk on Union Street Saturday evening, prompting some evacuations but no injuries.

“It was all contained underground,” Lynn District Fire Chief Jack Barry said Sunday evening. “We were able to flood the vault with dry chemical extinguisher and put it out pretty quickly. We were concerned that the fire could spread in the vault into adjacent buildings.”

Police and firefighters received a report of a disturbance at 7:07 p.m. Saturday in the area of 180 Union St. (almost opposite Burchstead Place) and initially heard reports of an explosion causing injuries, Barry said.

On arrival, firefighters reported finding nobody injured; but two grates in the sidewalk about 25 feet apart were each spewing smoke.

Barry said that the city buried utilities underground beneath Union Street and electrical wires can be accessed in periodic vaults beneath the pavement. Vents at each end of the vault open into the sidewalk, kind of like a subway grate.

Barry said firefighters evacuated a restaurant and a church service out of concern that the fire could travel through the vault into the adjacent buildings. But the fire did not spread, and firefighters left the scene before 8 p.m.

National Grid Spokeswoman Darlene Masse said that one utility workers believed the rain from earlier in the evening and day flooded the vault and caused a connection to short-circuit. Approximately a 15 customers were without power for an hour while utility workers made repairs.

Manhole explosions typically increase during the winter, when salt applied to roads to melt ice can fray cables that lie beneath the city streets.  After the insulation is damaged, the cables then can short when flooded during storm events, causing sparking fires, smoking incidents, and blasts due to the increased gas pressure inside the vault.   

Several hundred pound manhole covers can shoot in the air from that pressure built up.  Expect a significant increase in manhole fires due to the amount of salts used to melt the ice/snow this harsh winter.  Already most areas in the northeast have seen an increase in the number of incidents compared to previous years.