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TRANSCRIPT
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Streetlight Contact Voltage Testing
ITE/IMSA Joint Conference
February 13, 2012
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Presentation Outline
SCL Streetlight History
Streetlight Engineering Vision, Mission & Goals
System Condition & Inventory
Contact Voltage History
Contact Voltage Discovery
Testing Methodology
Lessons Learned
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SCL Streetlight History
1869 - City of Seattle Charter granted the Seattle City Council the power to provide street lighting
1885 - the Seattle Light Department, now Seattle City Light (SCL), maintained streetlights and managed power accounts for independent power suppliers throughout the central business district
1905 - City’s first power plant became operational making SCL responsible for both streetlights and power generation
1999 - Jurisdiction of arterial streetlights from Seattle Department of Transportation to SCL made SCL responsible for operations and maintenance of residential and arterial street lighting
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SCL Streetlight History (cont.)
Lights designed to simulate a clear full moon lit night
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SCL Streetlight History (cont.)
LED Conversion
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Cities ServedCities Served
Seattle Burien Lake Forest
Park Normandy Park
(portion) Renton (portion) Seatac (portion) Shoreline Tukwila (most) Unincorporated King County
Seattle Burien Lake Forest
Park Normandy Park
(portion) Renton (portion) Seatac (portion) Shoreline Tukwila (most) Unincorporated King County
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Streetlight Engineering Vision/Mission/Goals
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System Condition
Majority of the streetlight system is aging
Portions no longer meet current electrical code due to changes over the years
Failures and outages continue to increase
Contact voltage caused by aging infrastructure, weather, workmanship, rodent activity, copper wire theft, and corrosion
Current luminaires 25+/- years old
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System Condition (Cont.)
Life cycle estimates for system components
HPS Lamps – 4 to 5 years
Standard Cobra Head Luminaire – 20 to 25 years
LED Luminaires – 15 to 20 years
Electrical Wiring and Conduits – 20 to 75 years depending on material quality and type
Poles – 30 to 85+ years
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System Inventory
~85,000 Streetlights
131 sq. mile service territory
Primarily HPS Luminaires, residential LED conversion program in process
Annual revenue recovery: ~$13 million
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1B,1C,1D,1E,1F 3A,3B,3C,3E,3D 3D ARCH CLEV
ENT1 & ENT2 2PR 2F 2G
2JJ, 2KK 2BB 2H, 2L, 2J 2R 2O
2Z, 2HH 2N, 2M 2Y, 2PP 2W 1SP
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Contact Voltage History
19 deaths in 13 states have been reported in the media since the early 1990s
2004: grad student Jodie Lane was electrocuted in New York while walking her dogs - stepped on a slush-covered utility box with bad wiring
2005: Institute of Electrical and Electronics Engineers (IEEE) convened a Working Group to define and develop guidelines for mitigating contact voltage
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Contact Voltage Definitions
Results from abnormal power system conditions present between 2 conductive surfaces the general public and/or animals can come in contact with
Caused by power system fault current flowing through an impedance of available fault current pathways
Conductive surfaces include the earth and/or extensions of the earth such as concrete sidewalks and metal floor drains
Leaking of voltage is lost power not billable by utilities
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Contact Voltage Definitions (cont.)
Assets susceptible to contact voltage in an urban street-level environment
Metal poles
Handholes
Fiberglass poles with metal components
Concrete rebar-reinforced poles
Electrified signs
Traffic signals and traffic count meters
Street and pedestrian lights
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Contact Voltage Discovery
Thanksgiving Day 2010, dog was electrocuted when it touched an energized streetlight handhole cover
Combination of factors contributed to the incident Weather – there was melting snow on the
ground
Pinched wire in the luminaire
Improper grounding of the streetlight from installation
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Contact Voltage Discovery (Cont.)
As a result of media reports, 6 other pet owners notified SCL of similar reactions
Voltage detected either from a metal streetlight pole or metal equipment servicing the pole
SCL took immediate action to test all metal streetlight poles and equipment within its service territory
Implemented an annual contact voltage testing program
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Testing Methodology
Initially used 2 methods with 2 different contractors:
1. Manual testing
2. Mobile detection
Executed a 5-year contract for annual contact voltage detection program using mobile detection capability
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Testing Methodology (Cont.)
Decided to use SVD2000 mobile contact voltage detection system for annual testing because:
More efficient, 2011 scan performed in 31 days
Accuracy / sensitivity of objects less than 1 volt
Specialized equipment sends out a signal and detects elevated voltage in its monitoring area
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Testing Methodology (Cont.)
Manual investigations with Fluke 345 PQ-capable voltmeter, switchable 3000 Ω shunt resistor and handheld electric field detector, were performed where indicated
Covered 1,721 linear miles Tested 37,500 pieces of electrical equipment
associated with metal streetlight fixtures OSHA considers any current at or above 30 volts a
potentially dangerous level of electricity for heart fibrillation, and is the threshold to determine risk to the public
Used GPS maps to audit contractor’s data
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Testing Methodology (Cont.)
If elevated voltage detected, voltage is recorded and source located
Information is reported to SCL for further investigation and resolution
Voltage detected at or above 30 volts, requires securing the equipment from public contact and until SCL crews arrive to perform repairs or de-energize the equipment
Testing equipment does not distinguish between SCL assets and other touch potential assets in the right-of-way
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Testing Methodology (Cont.)
5 events detected at 30 volts or more, but only 2 of the detected events involved SCL equipment
3 remaining events involved private or by other organization ownership
Result comparisons from 2010, show a significant decrease in contact voltage events
2010: 158 events of electrified assets detected, 56 of which were discovered > 30 volts
2011: 61 events detected, 2 events > 30 volts
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Testing Methodology (Cont.)Annual Contact Voltage Event Results for SCL Assets - Years 2010 and 2011
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102
2
59
0
20
40
60
80
100
120
Voltage 30 or above Voltage below 30
Events
2010
2011
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Lessons Learned
City Light is taking the following proactive approaches to protect the public: Touch potential testing instituted for
both SCL crews and contractors, testing is performed prior to beginning work and after the work is finished
10-year Horizon Plan being implemented that prioritizes infrastructure replacement and refurbishment
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Lessons Learned (Cont.)
SCL has taken responsibility for testing and inspecting all streetlight equipment before it is energized Departmental Policy and Procedure (DPP)
being drafted to formalize responsibilities and processes for inspecting, commissioning and testing street lighting systems
Finally, SCL will continue to test its streetlight system annually and report the findings to the public
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Conclusion
Streetlights are an important part of a safe community
SCL is committed to maintaining the streetlight system and to do so safely
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More Information
To report malfunctioning streetlight or if an energized structure is suspected, contact the Streetlight Hotline at: (206) 684-7056 [email protected] www.seattle.gov/light/streetlight
SCL Contact Voltage Reports: www.seattle.gov/light/streetlight/streetlightsandcontactvoltage.htm
Toronto Hydro Contact Voltage Information:www.torontohydro.com/sites/electricsystem/residential/electricalsafety/Pages/contactvoltage.aspx
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Streetlight Engineering Contacts
Steve Crume, Streetlight Engineering Manager
206.615.1385
Emily Burns, Sr. Capital Projects Coordinator
206.733.9972