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Introduction
Introduction
Hi-Line Engineering is a consulting firm specializing in
the design distribution systems
We design 300 miles of line each year
Teach over 30 training classes on proper design of
overhead and underground distribution lines
Provide expert testimony regarding public contact with
distribution lines
General consulting for planning the expansion of
power systems Hi-Line Engineering is a consulting firm specializing in
the design distribution systems We design 300 miles of line each year Teach over 30 training classes on proper design of
overhead and underground distribution lines Provide expert testimony regarding public contact with
distribution lines General consulting for planning the expansion of
power systems Training for
North American Wood Pole Council
Training for
North American Wood Pole Council
Wood Pole Structure Design Seminar
Nashville
April 3-5
Nashville Sept
25-27
Focus on distribution line design
Conductor characteristics
Pole strengths
Calculation of wind loading
Pole-Top assemblies
Guying and Anchoring
Calculation of loading Wood Pole Structure Design Seminar
Nashville
April 3-5
Nashville Sept
25-27 Focus on distribution line design
Conductor characteristics
Pole strengths
Calculation of wind loading
Pole-Top assemblies
Guying and Anchoring
Calculation of loading Desire for Underground Utilities
Desire for Underground Utilities
The Public wants underground
utilities
Desire the college campus look
Most new subdivisions are fed
underground
Reported 9 out 10
Many comminutes require
underground utilities before
approving subdivision
Developers want underground
utilities and even advertise
underground utilities. The Public wants underground
utilities
Desire the college campus look Most new subdivisions are fed
underground
Reported 9 out 10
Many comminutes require
underground utilities before
approving subdivision
Developers want underground
utilities and even advertise
underground utilities. Commercial Developments
Commercial Developments
Developers desire underground service
Aesthetics
Utilitys also like underground to commercial
developments
Less expensive
Padmounts verse two-pole platform mounted
Vehicle damage is reduced
Clearance limitations Developers desire underground service
Aesthetics Utilitys also like underground to commercial
developments
Less expensive
Padmounts verse two-pole platform mounted
Vehicle damage is reduced
Clearance limitations Undergrounding Trends
Undergrounding Trends
One Alabama Cooperative
Experience
55% of new services are
underground in 2000
75% of new services are
underground in 2006
Streetscape projects
Urban beautification One Alabama Cooperative
Experience
55% of new services are
underground in 2000
75% of new services are
underground in 2006 Streetscape projects
Urban beautification
Comprehensive Plan for
Undergrounding
San Antonio, Tx
Colorado Springs, Co
Williamsburg, Va
Tocoma, Wa Comprehensive Plan for
Undergrounding
San Antonio, Tx
Colorado Springs, Co
Williamsburg, Va
Tocoma, Wa Desire for Underground
Desire for Underground
Communities want underground
Willingness to pay for underground
Cost in Aide
0-$1000s/lot
Selling point for new homes
Can it be justified?
Not affected by storms
No right-of-way maintenance
Considered safer Communities want underground Willingness to pay for underground
Cost in Aide
0-$1000s/lot Selling point for new homes Can it be justified?
Not affected by storms
No right-of-way maintenance
Considered safer Recent Studies
Florida
Virginia
North Carolina
Maryland
Recent Studies
Florida
Virginia
North Carolina
Maryland
After severe storms, the public/governmental
agencies want to replace overhead line with
underground lines
After severe storms, the public/governmental
agencies want to replace overhead line with
underground lines Cost Effectiveness of
Undergrounding
Cost Effectiveness of
Undergrounding
Cost per Mile of
Overhead Systems
$15,000 for 1-phase
$80,000 for 3-phase
$250,000 for extra large 3-ph
Service $1,500 to $2,500
25 kVA Transformer
$1,000
Cost per Mile of
Overhead Systems $15,000 for 1-phase $80,000 for 3-phase $250,000 for extra large 3-ph Service $1,500 to $2,500 25 kVA Transformer
$1,000
Cost per Mile of
Underground Systems
$25,000 for 1-phase
$160,000 for 3-phase
$1,500,000 for extra large 3-ph
Service $2,000 to $5,000
25kVA Padmount Transformer
$2,000
Cost per Mile of
Underground Systems $25,000 for 1-phase $160,000 for 3-phase $1,500,000 for extra large 3-ph Service $2,000 to $5,000 25kVA Padmount Transformer
$2,000 Cost Effectiveness of
Undergrounding
Cost Effectiveness of
Undergrounding
High initial cost of underground offset by
Reduction in tree trimming costs
(largest cost outside of power costs)
Reduction in vehicle accidents
(17% of highway deaths involve poles)
Reduction restoration costs
Reduction in line losses
Larger conductors
All the states that have recently studied and analyzed the cost
compared to the savings have the same conclusion
Undergrounding CAN NOT be justified based on economics High initial cost of underground offset by
Reduction in tree trimming costs
(largest cost outside of power costs)
Reduction in vehicle accidents
(17% of highway deaths involve poles)
Reduction restoration costs
Reduction in line losses
Larger conductors All the states that have recently studied and analyzed the cost
compared to the savings have the same conclusion
Undergrounding CAN NOT be justified based on economics Virginia 2005 Study
Virginia 2005 Study
Economic Benefit
Annualized
Benefits
Annualized Cost
Underground Power Lines
$10,000,000,000
O&M Savings
Negligible
Tree trimming savings
$50,000,000
"100-Yr" Post Storm rebuild
$40,000,000
Avoided Sales Lost
$14,000,000
Avoided Vehicle Accidents
$150,000,000
Avoided Outages
$3,670,000,000
Total
$3,924,000,000
$10,000,000,000
Cost is based on initial investment of $93,900,000,000 Service Life and Reliability
Service Life and Reliability
Service Life
Overhead lines 30-50 years
30 years for poles, 50 years for conductor
Underground lines 30 years
30 years for cable, could be less for padmounted
equipment
Reliability
Underground reliability fades after 25 years
Fewer outages but longer outages
North Carolina study reported
92 minutes for overhead outages
145 minutes for underground outages Service Life
Overhead lines 30-50 years
30 years for poles, 50 years for conductor
Underground lines 30 years
30 years for cable, could be less for padmounted
equipment Reliability
Underground reliability fades after 25 years
Fewer outages but longer outages
North Carolina study reported
92 minutes for overhead outages
145 minutes for underground outages Trending Differences Costs
Trending Differences Costs
Labor is about the same
Overhead material costs will track wood pole prices
Underground material costs track oil and metal prices
Conduit and cable insulation, padmounted cabinets Labor is about the same Overhead material costs will track wood pole prices Underground material costs track oil and metal prices
Conduit and cable insulation, padmounted cabinets Case Study
Case Study
Single family home
2,400 square feet
200 feet of 7,200 volt line
Transformer
150 feet of service conductor Single family home
2,400 square feet 200 feet of 7,200 volt line Transformer 150 feet of service conductor
Overhead
$2,704
Underground $4,763
Hybrid
$3,325
Overhead 7200 volt
Underground Service
(cost of conduit & trench = $706)
Overhead
$2,704
Underground $4,763
Hybrid
$3,325
Overhead 7200 volt
Underground Service
(cost of conduit & trench = $706)
200 ft
75 ft
75 ft Undergrouding the Last Span
Undergrouding the Last Span
The service drop to the house is vulnerable outages
Falling trees
Trees not trimming as aggressively on service drops
When a tree falls on service drop
Pulls the weather head off the house
The weather head is owned by the customer
He/She must make repairs before restoration of power
Undergrounding the last span will reduce outage times
Encouraged by some communities and utilities The service drop to the house is vulnerable outages
Falling trees
Trees not trimming as aggressively on service drops When a tree falls on service drop
Pulls the weather head off the house
The weather head is owned by the customer
He/She must make repairs before restoration of power Undergrounding the last span will reduce outage times
Encouraged by some communities and utilities Conclusions
Conclusions
Underground power is not cost-effective
According to four state commissions
Studies shows benefits
Reduced tree trimming
Reduced restoration cost from severe storms
Not enough benefits to justify cost
Public believes there is a value
Willing to pay for additional costs
Reason is aesthetics
As long undergrounding costs remains a small
percentage of the home cost
Home buyers will continue to demand underground Underground power is not cost-effective
According to four state commissions Studies shows benefits
Reduced tree trimming
Reduced restoration cost from sev