Seattle City Light identified and repaired 13 instances where its metal structures or equipment were improperly energized with at least 30 volts of electricity due to short circuits or damage to wiring during its 2015 annual contact voltage testing. One more instance was identified on privately owned equipment, the owner was notified and repairs were completed.
“Utilizing a mobile detection system, all conductive assets in the Seattle City Light service area were tested,” Interim General Manager and CEO Jim Baggs said. “City Light has taken a proactive approach and made great progress in the elimination of contact voltage exposure.”
The recent findings were similar to those from 2014, when 14 instances of voltage of at least 30 volts were identified on City Light equipment and fixed.
This is the sixth consecutive year the utility has tested its equipment for contact voltage. City Light started the annual tests along with a number of maintenance improvements and internal business process improvements in 2010 after a dog was electrocuted in Queen Anne when it stepped on an energized hand hold cover.
Whenever testing identified contact voltage of at least 30 volts, crews immediately de-energized the equipment and made repairs.
In the 13 instances of contact voltage over 30 volts involving City Light equipment, crews determined:
- Nine events were determined to be the result of bad wiring and connections
- One involved failed equipment
- One was related to a long-term active construction site where the actual cause has not been fully determined
- And two events were determined to be the result of pinched wires in the door of the luminaire during LED conversion. Retraining on proper luminaire installation was conducted with the contractor crews.
Testing also identified 42 instances of contact voltage less than 30 volts. Crews made repairs or de-energized all City Light equipment involved in those cases as well.
A number of factors can contribute to contact voltage, including aging infrastructure, weather, improper installation of equipment, rodent activity, copper wire theft and corrosion. To address these factors, City Light is working to strategically refurbish and replace infrastructure following priorities outlined in a 10-year horizon plan.
You can read the full report here.