A parking ban goes into effect beginning at 6 p.m. Wednesday evening on lower Main street and part of South Summer street in Edgartown, while work crews repair electrical lines that failed earlier this week. The lines supply electric power to a wastewater pumping station at the foot of Dock street.

“The lines failed, but we don’t know what the cause was,” said wastewater plant chief operator David Thompson early Wednesday.

While trucks and repair crews will take up the middle of the narrow street, traffic will be able to pass through where vehicles normally park. Town police ask that motorists to avoid the area if possible.

The parking ban covers South Summer street from Main street to the parking lot adjacent to town hall. Parking is also prohibited on Main street from South Summer street to Dock street. The electrical conduits pass underground along that route.

According Mr. Thompson, the electrical lines failed Monday evening, following a period of high wind and rainstorms the previous weekend. The wastewater pump station worked only intermittently, but enough to avoid any sewer backup

“It wasn’t operating well,” he said. “It was switching on and off, tripping out.”

Wastewater department personnel borrowed a generator from Oak Bluffs, under a collaboration agreement between the two towns. The diesel generator supplied power to the pump station since Monday’s failure.

Getting replacement parts caused a delay in repairs, but the components were scheduled to arrive on-Island Wednesday.

“It’s almost a thousand feet from town hall to Dock street,” Mr. Thompson said. “Getting that kind of length for that sort of cable, it’s not something people had laying around.”

Mr. Thompson said his crews will begin work about 8 p.m., and work through the night, if required. They will pull new cables through existing conduits under the street, and repair connections. If all goes well, repairs should be complete by Thursday morning.

In July 2008, there was a catastrophic failure of the same pumping station, when NSTAR equipment that carries power to the Island malfunctioned, triggering a shutdown of the system. The failure caused a sewer backup that filled a nearby restaurant basement with raw sewage.