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Con Edison Technology Enhancing Manhole Safety, System Reliability

Sensors in Pilot Program Are Latest Innovation Energy Company Is Deploying

Con Edison is installing sensors that detect heat and carbon monoxide in manholes and send a signal to the company indicating that equipment might need repairs.

By repairing damaged or worn cable in the manhole, the company can reduce the chance of a serious manhole event or service interruption. These manhole events usually occur when a mixture of melting snow and road salt washes into manholes, leading to the cables arcing.


As the insulation on the cable burns, it emits combustible gases. Limiting these events improves public safety and reduces customer outages.

“These sensors, along with other technologies we have begun using in recent years, protect New Yorkers and help us keep our service reliable through winter storms and summer heat,” said Michael Donohue, senior engineer in Con Edison’s Distribution Engineering department. “As we install these sensors, we’ll continue researching new ways to help our equipment perform superbly through the wide range of weather we get here in the Northeast.”

In its pilot program, Con Edison crews have installed 1,000 of the sensors and the company plans to install another 1,000 by the end of 2017.

The company chooses the manholes where it will install sensors based on analysis of its underground electrical delivery equipment. The company on an ongoing basis reviews area-by-area data on the performance of its equipment, the demands placed on it, the forecasted need for power, and other factors.

When a sensor signals a buildup of gas or heat, Con Edison engineers evaluate and determine whether to send personnel to the site.

The company’s operators estimate that the sensors could help reduce manhole events by 10 percent in the winter of 2017-’18.

It is just one of the methods Con Edison researchers have found effective on its expansive underground electrical-delivery system. That system includes more than 266,000 manholes and service boxes and 97,000 miles of cable supplying 2.5 million customers.

The company has installed more than 125,000 vented covers on its manholes and service boxes. The venting allows gases and heat to escape as opposed to building up inside the hole. That program began in 2005. (Click here to see a video on vented covers.)

In 2015, Con Edison began providing its crews with cameras that take infrared photos of underground electrical cables. If a photo shows a “hot spot” on a section of cable, it could indicate a defect on that could lead to a manhole event. Detecting these hot spots helps the company’s planners prioritize repairs. (See a video on infrared testing.)

Since Con Edison started the infrared program, company crews repaired more than 150 sections of cable with hot spots, preventing manhole events.

By the end of 2017, the company will have installed 1,000 latched covers, under a pilot program. The latch prevents a cover from lifting when heat and gases build up. (See a video on latched covers.)

Con Edison is a subsidiary of Consolidated Edison, Inc. [NYSE: ED], one of the nation’s largest investor-owned energy companies, with approximately $12 billion in annual revenues and $49 billion in assets. The utility provides electric, gas and steam service to customers in New York City and Westchester County, N.Y. For additional financial, operations and customer service information, visit, for energy efficiency rebates and incentives, and on Twitter and Facebook.

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