Con Edison continues to develop technology to keep pedestrians and pets safe from contact voltage on the streets of New York City.
Company crews now use hand-held directional electric-field sensors to zero in on objects that are energized. Con Edison crews investigating contact voltage reports sweep the device from side to side until the lights on the device glow bright red. The lights indicate the device is near an energized streetlight, sidewalk grating, fence or other object.
Con Edison developed the technology with the Electric Power Research Institute (EPRI). A video of the device in use is available at http://videos.tdworld.com/video/Contact-Voltage-Detection.
Contact voltage, sometimes called stray voltage, occurs when a defective electrical cable or wire energizes an object. Wet conditions and road salt make it more likely for these objects to conduct electricity.
The e-field sensor is the newest sophisticated tool Con Edison uses to locate objects energized by contact voltage. The heart of the program is a fleet of 15 mobile contact voltage detectors developed by the company's research and development department. The detectors are mounted on trucks that roll along city streets at night.
The company recently filed an annual report with the New York State Public Service Commission that showed 79 shocks were reported in its service area last year, 27 of which were Con Edison responsibility.
In 2004, the first year of Con Edison's program, 285 shocks were reported. Of those, 210 were the company's responsibility. Last year's numbers represented a slight increase from 2010, when there were 59 shocks, including 15 that were from the company's equipment, which the company attributed to last year's severe weather.
Twenty-five of last year's shocks were reported in January, when 36 inches (91 cm) of snow fell in New York City. And there were nine each in August and September, the two rainiest months.
Con Edison annually tests nearly 750,000 structures, including manholes, service boxes, underground transformers, and city or municipally owned street and traffic lights.
The company found and made safe 8,560 energized objects in 2011. About 35% of those were not the company's responsibility. When Con Edison finds contact voltage, it guards the area until repairs are made, even if it does not own the defective equipment.
For more information, visit www.coned.com.