Scanning: a way to detect energized objects in the pedestrian pathway
Since 2004 two methods have been used to detect energized objects in the pedestrian pathway: manual stray voltage scanning and mobile stray voltage scanning.
A person physically uses an electrical contact probe, called an HD-Probe, to determine if an object is energized. If the probe finds stray voltage, a more precise measurement is made with a digital volt meter.
After Jodie Lane’s death in 2004, the New York State Public Service Commission (PSC) required Con Edison to manually scan all of their assets, as well as the New York City Department of Transportation’s assets, annually. All energized objects detected with one or more volts were reported.
- Manual scanning is better than no scanning at all.
- Manual scanning uses an electrical detection probe, HD-Probe, which requires metal to metal contact. Many assets are painted making the reading unreliable.
- The HD-Probe will not identify stray voltage if the operator’s feet are also energized, a common occurrence.
- Only the utility’s assets are evaluated. Scaffoldings, sidewalks, fences, etc. are not evaluated as they are not owned by the utility.
- The process is very slow and very costly and yields relatively few energized object detections.
A sophisticated piece of equipment called an SVD2000 continuously monitors electric field strength from a vehicle moving at speeds of up to 20mph. Stray voltage signals are detected by the SVD2000 sensor unit and an audio signal alerts the vehicle operators with a pitch proportional to the strength of the voltage detected. A "moving chart" graphical display of the electric field strength is produced using video imagery from side-looking cameras. Video imagery and digital data (longitude, latitude and street address of detected stray voltage) is logged for recall and replay at any time.
Mobile scanning was developed by the Sarnoff Corporation at the request of Con Edison. Mobile scanning in New York City since 2006 has been performed by Power Survey Company, an offshoot of Sarnoff.
In addition to the SVD2000 detector, Power Survey Company has developed work methods and test protocols needed to operate the detector and perform the necessary follow up investigation needed to pinpoint the stray voltage location.
- Mobile scanning is 400% more effective at detecting energized objects than manual scanning.
- Mobile scanning is easily scalable. NYC started with one scan per year and now does 12 per year.
- Mobile scanning is not limited to detection of the utility’s assets. It detects energized sidewalks, fences, roadways, etc.
- Mobile scanning costs 10x less than manual scanning per energized object detected.