Maintenance Plan for Transmission and Distribution Overhead and Underground Lines - Docket No.
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THE UNITED ILLUMINATING COMPANY
Docket No. 20-12-44
Maintenance Plan for
Transmission and Distribution
Overhead and Underground Lines
Revised: 1/27/2021
Table of Contents
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1. Executive Overview .........................................................................................................3
2. Introduction ......................................................................................................................4
3. System Description ..........................................................................................................4
4. Vegetation Management...................................................................................................7
5. Maintenance Practices .....................................................................................................9
5.1. Construction and Maintenance Workforce Organization .........................................10
5.2. Maintenance of Assets and Systems by Area ...........................................................12
5.2.1. Overhead Distribution System .......................................................................12
5.2.2. Underground Distribution System .................................................................15
5.2.3. Overhead Transmission System .....................................................................17
5.2.4. Underground Transmission System ...............................................................18
5.2.5. Substations .....................................................................................................19
5.2.6. Vegetation Management ................................................................................21
5.2.7.General .............................................................................................................21
6. Summary of Updated Maintenance Practices ..................................................................22
6.1. Overhead System Changes .......................................................................................23
6.2. Substation Changes ...................................................................................................23
6.3. Vegetation Management Changes.............................................................................23
6.4. Underground Transmission System Changes ...........................................................23
7. List of Attachments ..........................................................................................................24
1: United Illuminating Service Territory Map ...........................................................25
2: Vegetation Management Specification ..................................................................26
List of Tables
1: System Peak Loads ..................................................................................................4
2: MWHR sales mix for the period 2017-2020 ...........................................................6
3: Breakdown of customers by class for the period 2017-2020...................................6
4: System Miles by Construction Type and Voltage Level ..........................................7
5: Construction / Maintenance Work Force Organization ...........................................11
6: Maintenance Practices, Overhead Distribution System ...........................................12
7: Maintenance Practices, Underground Distribution System .....................................15
8: Maintenance Practices, Overhead Transmission System .........................................17
9: Maintenance Practices, Underground Transmission System ...................................18
10: Maintenance Practices, Substations .......................................................................19
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1. Executive Overview
Goals and Objectives
Proper maintenance of The United Illuminating Company’s (UI or Company) transmission
and distribution facilities has played a major role in achieving high reliability, public safety,
and customer satisfaction, and is a key element of the UI corporate strategy. The Company
continues active development and implementation of maintenance processes to drive
efficiencies into maintenance activities. UI’s electric system maintenance practices focus on
cost effectiveness while maintaining high levels of service to our customers.
The United Illuminating Company’s Maintenance Program Goals are to:
o Work safely everyday
o Maintain reliability performance at 1998 levels
o Achieve these goals at the minimum cost to our customers
The United Illuminating Company’s Maintenance Plan addresses assets in six subsections:
o Overhead Distribution System
o Underground Distribution System
o Overhead Transmission System
o Underground Transmission System
o Substations
o Vegetation Management
Reliability Centered Maintenance
Since 1997, UI has employed a Reliability Centered Maintenance (RCM) program approach
to system maintenance. In general, this approach applies equipment inspection, diagnostic
testing, analysis of historical data, and other techniques, to determine the nature and timing
of preventive maintenance actions. Hence, in RCM, traditional “time-based” maintenance is
supplemented or replaced by predictive or “condition-based” maintenance. The specific
strategy for the UI electric system is to move toward condition-based maintenance while
continuing appropriate traditional time-based maintenance activities.
At UI, the Reliability Centered Maintenance program is a continually evolving process that
strives to understand an asset’s potential for failure by focusing resources on preservation of
system function, as opposed to traditional maintenance to preserve individual equipment
operation. This approach improves cost effectiveness by reducing unwarranted corrective-
reactive maintenance.
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2. Introduction
Maintenance is a dynamic process that combines analysis of historical data, carefully
developed procedures that use proven predictive maintenance techniques, and cost effective
time-based maintenance tasks. The judgment of experienced operating and engineering
personnel is continually sought out and incorporated into the Reliability Centered
Maintenance Program. UI has developed a work routine that strives to make preventive
action a daily responsibility. Electric System Operations personnel traveling in the territory
are encouraged to report any abnormal system conditions to the operating department in a
proactive manner. The goal of UI’s Maintenance Program is to maximize safety and
reliability of the distribution and transmission systems in a cost effective manner.
3. System Description
The United Illuminating Company is located in the southwest area of Connecticut on the
north shore of Long Island Sound. UI serves seventeen cities and towns surrounding the
principal cities of New Haven and Bridgeport. The service territory is approximately 335
square miles with a population of approximately 762,856 people (2019 estimates as reported
on the State of Connecticut Department of Public Health website http://www.ct.gov/dph/cwp/
view.asp?a=3132&q=388156).
System peak load for recent years is shown in the following table:
Table 1: System Peak Load, 2015 to 2020
2015 2016 2017 2018 2019 2020
Peak 1230 1264 1193 1274 1217 1222
Load
(MW)
Date of 9/08/15 8/12/16 7/20/17 8/29/18 7/21/19 7/28/20
P e a k
Load
The map provided in Attachment 1 shows the UI service territory and the municipalities
supplied within the service area.
To serve its customers, the UI Company owns, operates and maintains the following:
• 28 - 115/13.8 kV bulk distribution substations with a capacity of 1,980 MVA
• 4 - 115 kV transmission switching stations
• 2 - 345/115 kV transmission substations
• 1 – 115 kV generator interconnection station
• 115 kV interconnection station to railroad owned 115/26.4 kV
• 2 - 13.8/4.16 kV distribution substations with a capacity of 15 MVA
• Approximately 3,281 pole line miles of overhead distribution lines (1φ and 3φ).
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o This includes primary, secondary and aerial cable, excludes service conductors.
• 216 miles of underground conduit banks.
• 703 miles of underground primary cables (1φ and 3φ) consisting of direct-buried as well
as underground duct and splicing chamber construction.
• A majority of the distribution system is fed at 13,800 volts, with the remaining load
supplied at 4,160 volts.
• Two underground network systems in the downtown areas of New Haven and Bridgeport
utilize interconnected secondary cables (120/208Y volt) designed primarily for high-
density urban areas.
• Some of the larger downtown loads are supplied by 277/480Y volt systems that are not
interconnected and are called “spot networks”.
• The UI transmission system consists of 16 circuit miles of overhead 345,000-volt line, 94
circuit miles of overhead 115,000-volt line, 18 circuit miles of underground 115,000-volt
line, and 11 circuit miles of underground 345,000-volt line.
A summary of the conductor types used in the UI system is found in Table 4 at the end of this
section. This table contains mileage of conductor types categorized by voltage level. The
data for this table was obtained by using the Company’s Geographical Information System
(GIS).
The Company’s service area is composed of urban, suburban, and to a lesser extent rural
areas. The urban areas are located in the downtown centers of Bridgeport and New Haven,
as well as in the smaller cities and towns, including Fairfield, Shelton, Derby, Ansonia,
Stratford, Milford, West Haven, Hamden, and East Haven. The remaining service area is
mostly suburban.
Most of UI’s commercial customers occupy land adjoining the major inter-city highways,
such as I-95 and US #1 from Fairfield to East Haven, Route #8 from Bridgeport to Ansonia,
I-91 and US #5 from New Haven to North Haven and Routes #10 and #15 from New Haven
to Hamden. Most of the large industrial customers are situated along the Railroad Rights-of-
Way on the shoreline, and in the Housatonic and Quinnipiac River Valleys.
Almost all of the non-commercial areas are suburban residential tracts. The only true rural
area left in the service territory is in Easton, except for scattered farms in North Haven, North
Branford, and Orange, as well as state and local parklands. Much of the territory, including
the rural, suburban, and residential area just outside the urban centers, is heavily treed.
Service reliability, without question, is of vital importance to the viability of the Company as
well as the local economy and remains extremely important to the Company and all of our
customers. In particular, the very existence of our commercial and industrial customers,
which comprise approximately 58% of our sales base, depends on UI’s ability to provide
reliable service.
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The following table summarizes the MWHR sales mix for the period 2017-2020:
Table 2: MWh Sales Mix for the Period
2017-2020
Customer Class 2020
Original
2017 2018 2019 Budget
Forecast
Residential 41.52% 42.40% 41.80% 42.75%
Commercial 49.03% 48.41% 48.76% 48.32%
Industrial 8.70% 8.53% 8.74% 8.48%
Street Lighting 0.75% 0.65% 0.70% 0.45%
Total 100.00% 100.00% 100.00% 100.00%
Note: Sums may not add exactly due to
rounding
The following table summarizes the breakdown of customers by class for the period 2017- 2020:
Table 3: Breakdown of Customers by Class for the Period 2017 - 2020
Customer Class 2020
Original
2017 2018 2019 Budget
Forecast
Residential 300,681 302,811 304,132 305,887
Commercial 30,653 30,998 31,062 31,191
Industrial 1,009 964 975 935
Street Lighting 1,120 1,125 1,113 1,109
Total 333,463 335,898 337,283 339,122
Note: Sums may not add exactly due to
rounding
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The following table summarizes transmission and distribution system miles by construction type
and voltage level:
Table 4: Transmission and Distribu on System Miles by Construc on Type and Voltage Level
Circuit Miles
Construc on Type
15kV or less 115kV 345kV & Higher
Tree Wire 2482 0 0
Non-Tree Wire 167 94 16
Aerial Cable 206 0 0
Self-Suppor ng Cable 1 0 0
Underground Cable* 703 18 11
Totals 3559 112 27
Definitions:
Tree Wire:
All primary wire used in open wire construction that is covered with a 10/64 polyethylene
coating.
Non-Tree Wire:
All primary wire used in open wire construction that either has no insulation (bare) or is covered
with a material having little or no insulation value.
Aerial Cable:
Shielded primary cable suspended from a messenger attached to poles.
Self-Supporting Cable:
Unshielded insulated primary wire triplexed around a messenger attached to poles.
*Underground Cable:
Distribution: Includes both shielded primary cable in a splicing chamber and duct system, and
direct buried cable.
Transmission: Includes pipe type, gas insulated, fluid filled and solid dielectric in a splicing
chamber and duct system.
*Secondaries and services excluded
4. Vegetation Management
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tiThe United Illuminating Company remains committed to providing safe, reliable and cost
effective electric service. In January of 2014, UI began a Utility Protection Zone Program
with the goal of establishing a clearance zone extending 8 feet horizontally and ground-to-
sky vertically around all of its primary distribution lines. This plan was to be completed over
8 years. As a result of Docket No. 16-06-04, the program has been extended from 8 to 12
years.
In addition to the UPZ planned circuit miles program, the Company implements the
following vegetation management strategies to maintain or enhance the reliability of the
electric distribution system:
• Reliability Maintenance – The reliability maintenance program is designed to address
emergent customer and other third party identified tree conditions that may affect
electric reliability and tree work required to restore service.
• Direct Contacts the minimum level of pruning and removal needed to resolve direct
contact with energized electrical equipment, or visible signs of burning.
• Vine Management: Vine Management is the removal of climbing vines from poles
and guy wires.
• Distribution Rights-Of Way Line Clearance: Rights-of-Way Line Clearance is the
removal of trees and non-compatible shrubs on off-road distribution rights-of way.
Typically, such work is identified and generated during cycle maintenance and
through ROW inspections.
Distribution Line Clearance Specification – UPZ
The UPZ tree work specification is the only UI vegetation management specification for
planned UPZ circuit miles. For trees that are pruned for Reliability Maintenance, the
clearance zone will normally be 8 feet to the side, 10 feet below and 15 feet above primary
conductors. For trees that are pruned for Direct Contact, the minimum level of pruning will
be executed to resolve the direct contact or visible signs of burning.
The Distribution Line Clearance Specification establishes vegetation management clearance
within the UPZ in a rectangular area extending horizontally for a distance of eight feet from
any outermost electrical conductor or wire installed from pole to pole and vertically from the
ground to the sky. Desirable low height or ornamental trees that are already in the zone or
those that are planted under the Right Tree – Right Place program will remain. Compatible
trees and shrubs listed in the State Vegetation Management Task Force Report or added by
the DEEP may remain in or may in the future be planted within the UPZ.
The UPZ creates greater distance between the vegetation and conductor in order to reduce the
likelihood that vegetation would impact the electric system during extraordinary weather
events. This specification reduces the amount of vegetation that may come in contact with
the electric infrastructure and will improve the overall performance of the electric system.
8In January of each year, UI reports Vegetation Management performance metrics to PURA as
required in Docket No. 12-01-10 and Docket No. 16-06-04. UI provides the tree warden in
each town in its service territory a plan detailing the proposed roads where UPZ vegetation
management will take place in the forthcoming calendar year and an estimated time schedule
for the planned vegetation management.
UI’s strategy is to obtain abutting property owner consent for all non-emergent or non-direct
contact tree work far enough in advance of the work to optimize the use of the line clearance
crews. This method requires UI’s contractors to begin the notification process at least three
months in advance to achieve this strategy and fully implement the requirements of Public
Act 14-151.
UI continues to work with local tree wardens, as well as civic and professional groups, to
help educate customers about the proper selection and care of trees that may be planted near
UI’s electric facilities. In addition, safety brochures are distributed annually through bill
inserts, and other events are held to educate the public on the dangers associated with
energized wires and the importance of having qualified tree contractors or UI line clearance
crews remove hazardous tree growth. We believe that we can continue to provide safe,
reliable service in a cost-effective manner by working together with our customers in matters
of line clearance and vegetation management.
Transmission Vegetation Management Program
Transmission lines are maintained on a four year cycle (approx. 25% per year). The cycle
based tree and brush work is supplemented with inspection of 100% of the overhead
transmission lines. UI’s Transmission Vegetation Management Program (TVMP) complies
with the North American Electric Reliability Corporation (NERC) FAC-003-4 Standard,
covering all the transmission lines operated at 200kV and above, and specific lower voltage
lines designated by the Northeast Power Coordinating Council (NPCC) as being critical to
the reliability of the electric system in the region. Transmission line ROW are inspected
annually by foot patrol for the purpose of identifying vegetation conditions that could breach
the vegetation to conductor clearance requirements, impact electric service reliability or
create a hazard to the public. UI has implemented the use of Light Detection and Ranging
(LiDAR) imaging and processing capabilities to improve the inspection program. The
LiDAR survey identifies vegetation conditions that are prioritized and scheduled within the
annual planned right-of-way maintenance. Any vegetation conditions which are an imminent
threat to the operation or maintenance of the lines are addressed immediately. All data from
the inspections is captured electronically and then imported into a tracking database. Reports
are generated from this database to assist in developing work schedules and tracking work to
completion. The UI Transmission Arborist re-inspects all reported vegetation items, develops
the maintenance trimming schedule, prioritizes work and coordinates with the railroad
companies when work is performed along the Metro North or Amtrak railroad tracks. Field
audits are completed to ensure the work performed meets the TVMP requirements.
UI’s Vegetation Management Specification is appended to this document as Attachment 2.
95. Maintenance Practices
The primary goal of Reliability Centered Maintenance (RCM) is to keep equipment operating
properly while minimizing total maintenance costs. RCM uses proven predictive
maintenance techniques to schedule cost effective maintenance only when needed (based on
experience, inspection and testing results, manufacturers’ data, etc.) to prevent critical
failures.
It should be understood that the term maintenance, as used at UI, includes both inspection
and maintenance activities. UI crews perform construction, inspection and maintenance
activities, thereby developing a balanced, well-rounded work force and minimizing costs.
UI employees perform the majority of maintenance work on the distribution system, with the
exception of tree trimming, and pole inspection and treatment which are done by outside
contract crews. During peak constructions periods, outside contract crews may augment UI
crews on construction projects. Outside contract crews are also used on UI’s transmission
system for both major construction and maintenance functions.
Maintenance practices in the following sections are organized as noted below:
▪ Construction / Maintenance Work Force Organization
▪ Maintenance of Assets and Systems by Area
• Overhead Distribution System
• Underground Distribution System
• Overhead Transmission System
• Underground Transmission System
• Substations
• Vegetation Management (Attachment 2)
• General
5.1.Construction and Maintenance Workforce Organization The following is a staffing
summary by section and grade of UI’s construction and maintenance departments:
10Table 5: Construc on and Maintenance Work Force Organiza on:
Department Posi on Number
Manager, System Maintenance 1
Maintenance Engineer 5
System Maintenance
Civil/Structural Engineer 1
Total System Maintenance 8
Manager, Vegeta on Management 1
Line Clearance Arborist, Lead 3
Vegeta on Management Line Clearance Technician 1
Lead Analyst – Contract Administra on 1
Total Vegeta on Management 6
Chief Line Group Leader 14
Construc on Manager-UG 3
Elec Syst Const Scheduler 2
Lead Supv, Const Opers 3
Line Group Leader 24
Line Restora on Leader 14
Sr Line Worker 1st Class 23
Line Worker 2nd Class 19
Line Worker 4th Class 7
Power Delivery (PD) Mgr - Pwr Del OH/UG 1
Sr Admin Clk Opers 2
Sr Bus Systems Analyst UG 1
Supv Pwr Del/Transm&Subst 7
UG Cable Splicer 3rd Cls 3
UG Cable Splicer First Class 9
UG Inspector 3
UG Working Leader 2
Underground Specialist 3
Total Power Delivery (PD) 140
Glove Lab Tech 2
Lead Supv, Const Opers 1
Lead U lity Worker 2
Sr Admin Clk Opers 0
Substa on Elec 2nd Class 0
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tiSubst Electr Const&Maint 13
Transmission & Substa on (T&S) Subst Electrician Spec 10
Substa on Electrician First Class 4
Substa on U lity Worker A 2
Substa on U lity Worker B 1
Supv Pwr Del/Transm&Subst 4
U lity Worker B RC 0
Total Substa on (T&S) 39
Electrical Test Assistant 7
Electrical Test Assistant B 0
Electrical Test Asst A 0
Engineer - Test 0
Engineer - Test Comm Systems 0
Lead Electrical Test Tech 7
Test Department
Lead Engineer - Test 0
Mgr - Pwr Del/T&S/Test 1
NERC Coordinator ESO 1
Principal Engineer - Test 2
Supv T&S Test 1
Total Test 19
Total Construc on & Maintenance Work Force 206
2. Maintenance of Assets and Systems by Area
The Company’s new work management system called SAP® has a module to manage the
maintenance of equipment. SAP® serves many functions, as it contains asset record data
along with an asset registry, and also generates work orders associated with preventive and
corrective maintenance plans. Several other databases are utilized in conjunction with
SAP® for implementing the RCM plan. These databases are linked where possible. The
Maximo® software application is no longer used to implement maintenance activities and is
only being used to store historical records.
UI visually inspects its overhead equipment in accordance with defined RCM programs
and whenever work is being performed on the system. The major components of UI’s
Overhead Distribution System are identified below. Details of maintenance and inspections
are noted in each asset category.
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tiIt should be noted that, in the course of any inspection and maintenance process described
in this report, all hazards, damage, and other abnormal conditions affecting equipment on
the UI system, are immediately reported to appropriate supervision, who then analyze the
situation and coordinate corrective actions. Also, additional attention is given to any
equipment as deemed appropriate by Substation Maintenance and T&D Networks
Maintenance.
The following tables list maintenance practices for major components of the overhead and
underground distribution and transmission systems
2.1. Table 6: Maintenance Prac ces, Overhead Distribu on System
Category Sub Category Frequency Task Descrip on Notes
Includes poles, ancillary
equipment, wire and cable,
During pole
hardware, fault indicators,
inspec on and
General Visual Inspec on lightning arresters, switches
when working on
and other equipment
pole
associated with an
installa on.
Poles, 6 Years and when Above ground line
10 years old working on pole
remedial treatment applying wood preserva ve
for decay if necessary. and internal fungicide for
decay.
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tiTable 6: Maintenance Prac ces, Overhead Distribu on System (con nued)
Category Sub Category Frequency Task Descrip on Notes
During pole
Wire, inspec on and
Visual Inspec on Problems reported in the
All when working on
pole Circuit Interrup on
Repor ng System are
Overhead Wire
Wire, reviewed for further
Annual Infrared Inspec on
3 phase lines inves ga on and correc ve
ac on
Wire, Performance
Infrared Inspec on
Single phase lines Based
A dielectric test is
performed whenever a
Dielectric test of
All Upon Installa on sec on is replaced or a
insula on integrity
cable termina on or splice
is replaced.
Aerial Cable In addi on to a visual Aerial PILC Cable s ll
inspec on when remains a ached to bridge
Paper Insulated
working on a pole. overpasses where
Lead Covered As above for
The majority of this installa on of splicing
(PILC), 13.8kV Aerial Cable
type of cable has been chambers and ductline are
Circuits
replaced on a required to facilitate
programma c basis. replacement
Insulators,
Lightning
Arresters,
3 phase lines Annual Infrared Inspec on
Hotline Clamps,
S rrups and
Splices
3 phase lines Annual Infrared Inspec on
Switches,
Disconnects and Performance
Fused Cutouts Single phase lines Infrared Inspec on
Based
Failed units are replaced
when found. System wide
Overhead Fault replacement will be based
All See Notes Replace
Indicators on failure rate, expected
ba ery life and technology
advancements
Transformers whose PCB
content is unknown, are
loaded at or near
nameplate ra ngs and
U liza on
See Notes those found in poor
Transformers
Pole Mounted condi on have been
Transformers iden ed and are included
for replacement in the
Company's 10 Year Plan
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tiElectronic monitoring
Step-down Monitored as
devices monitor phase
Transformers Required
loading
15Table 6: Maintenance Prac ces, Overhead Distribu on System (con nued)
Category Sub Category Frequency Task Descrip on Notes
Signal tested through
SCADA during
Radio As Needed
commissioning and
Controlled troubleshoo ng
Pole Mounted
Capacitor Banks Annual Visual Inspec on
Fixed Annual Visual Inspec on
All Annual Infrared Inspec on
Opera onally tested and
inspected.
Ac on taken based on
Opera ons counter
Pole Mounted Annual current RCM criteria and
recorded, voltage and
Voltage All data review.
se ngs con rmed with
Regulators
asset records
Annual Infrared Inspec on
Gas pressure, Ambient
The control ba ery is
temp, Opera ons counter
replaced on 4 year cycle,
Bi-annual recorded, ba eries tested
or when ba ery tes ng
All and recorded for asset
Pole Mounted fails.
tracking.
Reclosers
Annually Infrared Inspec on
Internal and Opera onal Based on current RCM
Oil Insulated 10 Years
tes ng criteria
Each municipality is
responsible for repor ng
lights that are out. UI is
Repair or Replace as responsible for repairing
Failure
required the lights once they’re
reported. Failures are
reported by customers,
Street Lights All police and UI personnel.
The Company began a
LED head replacement
program for municipal
See Notes Re-lamp
lights in 2015. Private
Area Ligh ng re-lamping
will begin Q1 2020.
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ti2.2. Table 7: Maintenance Prac ces, Underground Distribu on System
Category Sub Category Frequency Task Descrip on Notes
During inspec on Visual Inspec on of
and when electrical components and
General
working at a hardware, and structural
speci c loca on elements
Visual inspec on of the Equipment includes
Splicing
electrical and physical grounding, cable racks,
Chambers Splicing
10 Years condi on of the structure cable supports, covers,
and Chamber
and equipment contained roofs, frames and other
Secondary
therein. structural elements.
Network Vaults
Visual inspec on of the Equipment includes
electrical and physical grounding, cable racks,
Secondary
Annual condi on of the structure cable supports, covers,
Network Vault
and equipment contained roofs, frames and other
therein. structural elements.
Visual Inspec on including
protector status, nitrogen
Network
Annual blanket pressure and
Protectors
overall condi on
Network assessment
Transformers
Visual Inspec on including
Network
oil level inspec on and
Transformers Annual
recording and overall
and Switches
condi on assessment
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tiTable 7: Maintenance Prac ces, Underground Distribu on System (con nued)
Category Sub Category Frequency Task Descrip on Notes
When any work to
All Primary the electrical
Dielectric Tes ng
Cable insula on of a
cable is performed
Replacement of
Primary Cable,
remaining PILC cable
Paper Insulated Some of the PILC has been
As above for will be done based on
Lead Covered replaced on a
Wire and Cable Primary Cable performance and
(PILC), 13.8kV programma c basis.
poten al failure impact
Circuits
on system reliability.
Solid Dielectric As above for Replacement is
Primary Cable Primary Cable performance based
During inspec on
Distribu on
of the splicing Visual inspec on
Cable
chamber or vault
Padmounted
Visual inspec on for safety
Transformers
5 Years hazards, security, electrical
and Junc on
integrity and damage
Enclosures
Visual inspec on for safety
PME, PMH &
Annual hazards, security, electrical
G&W
integrity and damage
Padmounted
Switches Visual inspec on for safety
Vista 2 Years hazards, security, electrical
integrity and damage
Visual inspec on for safety
Second physical barrier
hazards, security, electrical
Transclosures 5 Years installed on all loca ons
integrity and damage
Abnormal condi ons
Transformer are brought to the
4 Years Visual inspec on for safety
Vaults customer's a en on for
hazards, security, electrical
remedia on and work
integrity and damage
Annual is scheduled
appropriately
Customer-
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tiCustomer- These installa ons are
Owned Facili es being replaced or
upgraded to meet
current NESC Standards
Transformer
based on priori za on
Cages
established from the
On-going program
inspec on program,
when the customer’s
service is abandoned,
at the customer’s
request or when system
upgrades are required.
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ti2.3. Table 8: Maintenance Prac ces, Overhead Transmission System
Category Sub Category Frequency Task Descrip on Notes
Inspected by outside
contractors. Inspec on
includes items such as ground
All 5Years
conductor integrity, paint
condi on, installa on of
proper signage, etc.
Above ground visual and Climbing inspec ons
Towers below ground level are performed as
Wood 10Years excava on to depth of 18” required.
with remedial treatment if
necessary
Test and review results for
Cathodic Protected proper opera on of the
2 Years
Steel Structures passive cathodic protec on
system
5 Years Visual inspec on
Visual inspec on by air
(helicopter) which includes an
Connectors, Annual
All infrared thermography
Conductors, inspec on
Termina ons
and Insulators Condi on-
Corona Imaging
based
Substa on Visual and thermography
Bi-annual
Components inspec on
All 5 Years Visual inspec on of condi on
Test and review results for
Founda ons Cathodic Protected proper opera on of the
2 Years
Caissons passive cathodic protec on
system
Vegeta on Annual Visual Inspec on
Right-of-Ways Iden fy and measure
Light Detec on and
(ROW) vegeta on clearances to
Ranging Inspec on 2 Years
conductors on and along UI
(LiDAR)
ROW
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ti2.4. Table 9: Maintenance Prac ces, Underground Transmission System
Category Sub Category Frequency Task Descrip on Notes
Addi onal
inspec ons are
Termina on performed through
Annual Visual inspec on
Support Structures bi-monthly
substa on patrol
inspec ons.
When working
Visual inspec on of
All Components in a speci c
accessible por ons
loca on
Visual and Thermography
Termina ons Bi-annual
Inspec on
High Pressure Fluid
Filled (HPFF) Cable 3 Years
and Termina ons
Addi onal
High Pressure Fluid inspec ons of
Filled (HPFF) GIS accessible
Cable and Cable 6 Years
Enclosed equipment are
Termina ons Fluid is tested for dielectric
Termina ons performed during
quality and dissolved various substa on
Low Pressure Fluid gasses. inspec ons.
Filled (LPFF) Cable 2 Years
and Termina ons
Low Pressure Fluid
Filled (LPFF) GIS
6 Years
Enclosed
Termina ons
Solid Dielectric
2 Years Visual inspec on
Cable
5 Years, during
High Pressure Fluid
cable inspec on
Filled (HPFF) and
or when
High Pressure Gas
working in a
Filled (HPGF) Condi on assessments are
speci c loca on
done when inspec ons
Low Pressure Fluid indicate further ac on,
2 Years which includes an
Filled (LPFF) Lines
accelerated systema c
Splicing Chambers 115kV and 345kV evalua on of the present
2 Years
Solid Dielectric condi on and future
maintenance/replacement
In accordance
requirements for the
with the
345kV Solid underground
requirements of
Dielectric Lines in infrastructure.
the Conn DOT
ConnDOT Right-of-
Bridge
Ways
Inspec on
Manual
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tiAll Monthly Visual inspec on
These are the sample
Cable
Dielectric Fluid 3 Years points for the HPFF Cable
Pressuriza on and
noted above
Pumping Systems
High and Low
2 Years Tested and Calibrated
Pressure Set points
Table 9: Maintenance Prac ces, Underground Transmission System (con nued)
Category Sub Category Frequency Task Descrip on Notes
Output is veri ed at
intermediate test points
2 Years and at the underground
cable extremi es in the
Ac ve Cathodic substa on.
Protec on Systems
Rec er visual condi on
assessment. Voltage and
2 Months
current values are
recorded and reviewed.
2.5. Table 10: Maintenance Prac ces, Substa ons
Category Sub Category Frequency Task Descrip on Notes
Bulk Substa on Outside
Includes exterior and
current carrying equipment Bi-annual
interior components.
equipment and
Infrared Thermography Ac on taken based
equipment
Distribu on Inspec on on current RCM
accessible
Substa on current Annual criteria and data
within the
carrying equipment review.
building
Visual inspec on of overall
condi on including
electrolyte levels (if In accordance to
2 Months industry accepted
applicable), voltage and
Sta onary Ba ery All
current levels and physical standards and
Systems Installa ons
condi on of components applicable NERC /
NPCC requirements
Conductance and voltage
Annual
tes ng and trending
Oil quality and Dissolved
Annual Gas Analysis (DGA) is
All performed and reviewed
2 Months Visual Inspec on
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tiThe 345kV
Bulk and Transformers have
4 Years 115kV Power factor and excita on
Transmission on-line monitoring
6 Years 345kV tes ng for the integrity of
Transformers and Substa ons systems which allows
insula ng materials,
Reactors for the 6 year cycle
windings, bushing
insula on. Load Tap Distribu on
Changer opera on. substa on
Opera onal tes ng of transformers are
Distribu on external components is tested only if infrared
Condi on based performed to ensure the
Substa ons inspec ons, oil
proper opera on of alarms tes ng or a visual
and monitoring equipment. inspec on detect an
issue
Internal inspec ons
and overhauls are
Timing and mo on, power condi on based but
Transmission Class
Bulk Oil (OCB) 2 Years factor tes ng and oil quality typically will not
Circuit Breakers
analysis exceed the
manufacturer’s
recommenda on
Table 10: Maintenance Prac ces, Substa ons (con nued)
Category Sub Category Frequency Task Descrip on Notes
Level 2 (major), 10 year
frequency: Outage required,
isola ng switches opened
10 Years and grounds applied as Internal inspec ons
required, Level 1 Items plus and overhauls are
Timing and Mo on, Alarm condi on based but
Transmission Class Gas Insulated points, Contact Resistance typically will not
Circuit Breakers (SF6)
Level 1 (minor) 5 year exceed the
frequency: Thorough visual manufacturer’s
inspec on, alarm se ngs, recommenda on
5 Years
hydraulic uid level and gas
moisture analysis
Air Magne c visual, mechanical, and
7 Years
(ACB) electrical inspec on,
Per Manufacturer’s
lubrica on, insula on
Distribu on Class recommenda on or
Vacuum resistance and contact
Circuit Breakers based on industry
Interrupters 10 Years resistance (measure the
best prac ce.
(VCB) level of atmosphere inside
vacuum interrupters)
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tiIncludes tes ng of security
systems, security inspec ons
2 Months and
of interior and exterior
whenever a
facili es, re-ex nguisher
sta on is visited
inspec ons, rst-aid kit
inspec ons and similar tasks
NERC standard
Security and CIP-006 requires
Safety periodic tes ng of
the system.
Maintenance and tes ng of Performing this
Annual security components and tes ng with our
Buildings and communica ons exis ng perimeter
Structures alarm tes ng
u lizes the same
resources to
perform both tests.
Facili es are cleaned,
opera on counts are taken
General 2 Months
and minor maintenance
ac vi es are performed
Gu ers and downspouts are Selected
Annual
inspected and cleaned substa ons
Roof Systems
Substa on roofs are
4 Years
inspected
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tiTable 10: Maintenance Prac ces, Substa ons (con nued)
Category Sub Category Frequency Task Descrip on Notes
Electrical integrity tes ng
and visual inspec on, Maintenance is
7 Years
replacement of cans or done in conjunc on
Capacitor Bank All OR
blown fuses, VBM ductor with ACB and VCB
10 Years
and hypot test, general maintenance cycle
cleaning by Substa on
Measure and recording
secondary voltage to iden fy
CCVT Secondary
problems while the failure is
Voltage All 3 Years
in its infancy. Inspect the
Trending
CCVT secondary junc on box
and internal components.
Voltage reduc on system
All Bulk communica on tes ng.
Voltage Reduc on Distribu on Annual Verify 2.5% and 5% voltage
Substa ons reduc on can be ini ated
from control center.
Systems include
Protec ve
protec ve relaying,
Systems and
ba eries and
Substa ons as
ba ery chargers,
de ned by North As described in NERC
circuit breakers,
American Electric Standard
As speci ed in transformers,
Reliability PRC-005-6 “ Protec on
NERC Standards protec ve relaying
Council (NERC) System Maintenance ”
telecommunica on
Protec ve Systems Standards and
s, Sudden Pressure
Northeast Power
relaying and
Coordina ng
Automa c
Council (NPCC)
Reclosing relaying
Non-Bulk Suspended based
Based on Test and adjust protec ve
(Distribu on) on current removal
removal program relaying as required
Sta ons schedule
2.6. Vegetation Management
The Vegetation Management Plan is described in Section 4. The current “Vegetation
Management Specification” for 2014 through 2025 is included as Attachment 2.
2.7. General
Employee awareness of system conditions constitutes a vital source of information for UI to
address maintenance requirements. In addition to the maintenance practices described in
Section 5.2, inspection and maintenance activities incorporate job tasks to identify vandalism
and theft, and a follow-up reporting mechanism to take corrective action. Employees, as they
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titravel to their work locations throughout UI’s territory, are encouraged to be observant and
report any abnormal conditions to Electric System Operations & Maintenance so that
appropriate action can be taken. This information, along with reports via telephone or
written communication from our customers or others regarding abnormal system conditions,
is captured in the computer-based Customer Request System. It is then forwarded to Electric
System Operations & Maintenance for investigation and resolution, as required. The trouble
conditions and subsequent resolution is captured in the customer call system, SAP.
6. Summary of Updated Maintenance Practices
Inspection and maintenance is currently being performed as described in earlier sections.
The following tables summarize the recommended changes to the maintenance cycle and
practices for the major components of the T&D system.
The Company continues to operate and maintain its system generally using the same
practices that were in place as of the Maintenance Plan dated December 11, 2018. The
maintenance practices in use are defined in our Reliability Centered Maintenance program,
which has been in effect for approximately seventeen years. The Company continuously
looks for opportunities to improve both operational performance and cost efficiency.
In response to Docket No. 13-01-19, “Application of The United Illuminating Company to
Increase Rates and Charges”, PURA approved $100 million for an 8 year plan for vegetation
management during 2014-2021. In response to Docket No. 16-06-04, “Application of The
United Illuminating Company to Increase Rates and Charges”, PURA approved $162 million
for a 12 year plan for vegetation management extending the program to 2025. This storm
resiliency program is based on Enhanced Tree Trimming (ETT) practices as presented in the
State’s Vegetation Management Task Force (SVMTF) report. The major components of UI’s
proposed program are:
UPZ is UI’s storm resiliency tree work specification, creating an eight-foot side clearance
ground to sky, retaining desirable low height or ornamental trees within the zone or those
that are planted under the Right Tree – Right Place program. Additionally, the Company
will identify and remove whole or parts of hazardous trees from outside of the zone that
could fall causing damage to utility infrastructure, facilities or equipment.
UI will document and track all objections, requests for modification and decisions made
by municipal tree wardens and the State Department of Transportation through the full
execution of Public Act 14-151 that cause nonconformities, or areas where UI is not able
to meet these specifications within and outside of the Utility Protection Zone (UPZ).
Instances of outages caused by nonconforming trees will be documented and considered a
reportable performance attribute.
In January of 2019, the Company implemented a Targeted Risk Management program
where it schedules entire circuits for the pruning and removal of trees that are in direct
contact with the conductors or have visible signs of burning. This was done to mitigate
26the effects of an extended cycle on safety, visual and physical access to the lines,
equipment damage, and reliability.
As a result of Docket No. 18-12-25 the Company ceased the Targeted Risk Management
program January 1, 2021.
In regards to the impact on the schedule, compliance with PA-14-151 has a negative impact
on crew productivity and schedule completion because of the disruption it causes to the plan
and subsequent flow of work. The process required to resolve property owner objections,
requests for modification and no contacts (properties where the owner cannot be contacted in
person) is time consuming and results in tree crews working in an inefficient manner rather
than systematically moving down the road. The end result is increased non-productive time.
Other impacts associated with the implementation of the act are the time and effort necessary
to collect and manage the data requirements, and the municipal tree wardens and State
DOT’s ability to provide timely decisions on objections and requests for modification.
The cost of traffic control performed by municipal police officers continues to impact the
program cost and schedule. As the portion of the annual budget that goes towards traffic
control continues to increase, fewer scheduled miles can be completed. The cost for police
officers and vehicles continue to rise at an alarming rate and are becoming even more
disproportionate to the cost of a fully qualified and equipped line clearance tree crew or a
certified traffic control specialist. For example, the average cost of an officer and police
vehicle is $96 per hour. When compared to the cost of a tree crew with equipment at $128
per hour, the cost for municipal police officers paid at overtime and police car is out of
balance for a service that can be provided with a certified flagger at $25 per hour. Please
note these increases also impact all capital and maintenance costs associated with the
electrical Distribution infrastructure for which all costs are borne by Connecticut customers.
1. Overhead System Changes
Category Sub Category Change Ra onale for Change
N/A N/A No Changes N/A
6.2. Substa on Changes
Category Sub Category Change Ra onale for Change
N/A N/A No Changes N/A
3. Vegeta on Management Changes
Object Change Ra onale for Change
The Company’s schedule for Vegeta on
Vegeta on Management has been changed from an 8-
Docket No. 16-06-04 PURA Final Decision
Management year (2014-2021) to a 12-year schedule
(2014-2025).
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ti4. Underground Transmission System Changes
Category Sub Category Change Ra onale for Change
Corrosion issues on cable supports have
Visual inspec ons been corrected and no longer require
Cable and Cable Solid Dielectric
changed from Annual to monitoring. Cycle extension has been
Termina ons Cable
a 2 year cycle jus ed by a review of recent annual
inspec on data showing no ndings.
Completed in conjunc on with cable
Visual inspec ons inspec ons (above). Cycle extension has
Splicing Solid Dielectric
changed from Annual to been jus ed by a review of recent
Chambers Cable
a 2 year cycle annual inspec on data showing no
ndings.
7. List of Attachments
1. UI Service Territory Map
2. Vegetation Management Specification, November 2014
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fiATTACHMENT 1
The United Illumina ng Company
Service Territory Map
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tiFair eld County New Haven County
Bridgeport Ansonia
Easton Derby
Fair eld East Haven
Shelton Hamden
Stra ord Milford
Trumbull New Haven
North Branford
North Haven
Orange
West Haven
Woodbridge
Internal Use
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tfATTACHMENT 2
THE UNITED ILLUMINATING COMPANY
VEGETATION MANAGEMENT
SPECIFICATION
Revised November 2014
Table of Contents
Internal UseVegetation Management Specification
The table of contents is empty because you aren’t using the paragraph styles set to appear in
it.
Introduction
The United Illuminating Company remains committed to providing high levels of reliability, while
simultaneously ensuring customer safety and satisfaction, and controlling cost. In 2013, the Company
completed the sixteenth year of the Performance-Based tree trimming program. All customer requests and
concerns about tree conditions are investigated and tree work is performed as required to eliminate those
concerns whether from an electric safety or reliability point of view.
From 1997 to 2013 the overhead distribution line clearance program consisted of a split four-year and
eight-year cycle for planned tree trimming. The three-phase portion of the system was trimmed on a four-
year cycle, while the single-phase portion of the system was trimmed on an eight-year cycle or where
performance triggered more frequent trimming. Any single-phase portion of the system that experienced
two or more tree related outages in a 36-month period was, at a minimum, trimmed to minimize the
potential for future outages. Other system modi ications, such as reconductoring bare wire with covered
conductor, may also be performed to help minimize the potential for future tree related outages. In
addition, tree work is completed at new construction sites as needed.
Beyond the Line Clearance planned circuit miles programs, the Company implements the following
vegetation management programs to maintain or enhance the reliability of the electric distribution system:
• Hazardous Trees: The Hazardous Tree program requires the complete removal to ground of all
identi ied trees. Hazard trees are identi ied in several ways including; UI vegetation management
resources, contractor permissions personnel, tree trim crews, town tree wardens and customers.
The hazard tree removal program is designed to remove trees identi ied as dead, dying, diseased or
structurally defective and located outside of the normal trim area, but pose a potential hazard to UI
facilities. The process involves identi ication of hazardous trees through the circuit trimming
program, reliability engineer, and Line Clearance Arborist and Technicians followed by
communications with customers, CDOT and/or municipalities to inform them of the hazard and to
obtain their consent to remove.
• Vine Management: Vine Management is the removal of various vines from poles and guy wires.
• Distribution Rights-Of Way Line Clearance: Rights-of-Way Line Clearance is the removal of
overgrowth on the distribution rights-of ways. Typically, such work is identi ied and generated
through ROW inspections and maintenance trim cycles.
Transmission lines are trimmed on a four year cycle (approx. 25% per year). The cycle based trimming is
supplemented with inspection of 100% of the overhead transmission lines. UI’s Transmission Vegetation
Management Program (TVMP) complies with the North American Electric Reliability Corporation (NERC)
FAC-003-4 Standard, covering all the transmission lines operated at 200kV and above, and speci ic lower
voltage lines designated by the Northeast Power Coordinating Council (NPCC) as being critical to the
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reliability of the electric system in the region. Transmission line ROW are inspected annually by foot patrol
for the purpose of identifying vegetation conditions that could encroach the vegetation to conductor
clearance requirements, impact electric service reliability or create a hazard to the public.
UI continues to work with local tree wardens, as well as civic and professional groups, to help educate
customers about the proper selection and care of trees that may be planted near UI’s electric facilities. In
addition, safety brochures are distributed annually through bill inserts, and other events are held to
educate the public on the dangers associated with energized wires and the importance of having quali ied
tree contractors or UI line clearance crews remove hazardous tree growth. We believe that we can continue
to provide safe, reliable service in a cost-effective manner by working together with our customers in
matters of line clearance and vegetation management.
Scope
The scope of this speci ication is to provide requirements and guidelines for line clearance pruning and the
removing of trees, brush and other vegetation in close proximity to overhead electric distribution facilities
located on public and/or private rights-of-way.
General:
• The Company: The United Illuminating Company (UI)
• Contractor: The irm that has been awarded a formal contract to perform work
Regulations
All work practices and de initions, except as otherwise speci ied herein, shall be in accordance with all
applicable Industry, Federal, State and Local laws and regulations, approved standards and safety practices.
These include all applicable sections of the following but are not limited to:
▪ OSHA 29CFR 1910.269 Electric Power Generation, Transmission & Distribution
NERC FAC-003-4 Transmission Vegetation Management Program or current standard
▪ ANSI A300 “Standard Practices for Trees, Shrubs and Other Woody Plant Maintenance”
▪ ANSI Z133.1 “Pruning, Trimming, Repairing, Maintaining and Removing Trees, and Cutting Brush –
Safety Requirements”
▪ NESC
▪ Connecticut General Statutes
▪ Department of Transportation
▪ Local Ordinances
▪ “Pruning Trees Near Electric Utility Lines” by Dr. Alex L. Shigo
▪ Best Management Practices, Utility Pruning of Trees
Evaluation
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Each tree must be evaluated individually at least 10 days prior to any non-emergent or non-DC tree work
being performed by contractor work planners and/or crew personnel. At the time of the evaluation,
consent will be obtained from the property owner. Consideration must be given to the tree species,
condition, growth rate and failure characteristics, PROW limitations, tree location, the potential combined
movement of vegetation and conductors during routine winds, and sagging of conductors due to elevated
temperatures or icing when performing line clearance. This evaluation should include growth rate, species,
shape, condition and location of the tree and the likelihood of encroachment to the UPZ. When requesting
written consent for tree pruning or removal from municipal tree wardens, the State Department of
Transportation, abutting property owners and private property owners, UI’s tree contractor Work Planners
will use the 8 foot line clearance dimension as the starting point for evaluation of the UPZ and will normally
request the removal of all encroaching trees and limbs. The actual distance will result from the required cut
of the tree so that a healthy tree remains.
Pole mounted electrical equipment such as transformers, capacitors, switches, etc. should be provided at
least ten (10) feet of clearance and in accordance with the – UPZ.
Secondary conductors should be cleared such that tree limbs do not rub conductors or entangle the wire.
A. Distribution Line Clearance Speci ication– Utility Protection Zone
UPZ establishes the "utility protection zone" which is the rectangular area extending horizontally for a
distance of eight feet from any outermost electrical conductor or wire installed from pole to pole and
vertically from the ground to the sky.
UPZ includes cutting, trimming and removal of tree limbs or trees within the utility protection zone
and retaining desirable low height or ornamental trees that are already within the zone or those that
are planted under a Right Tree – Right Place program. Additionally, the Company would identify and
remove in whole or in part hazardous trees that could fall from outside of the zone causing damage to
utility infrastructure, facilities or equipment.
The following drawings illustrate the Utility Protection Zone:
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35Vegetation Management Specification
36Vegetation Management Specification
B. Other Clearance and Operational Requirements
Trees or limbs imminently hazardous to any part of the Distribution System shall be patrolled and
mitigated with noti ication to and approval from quali ied UI personnel. Photographic evidence of the
imminent threat is secured prior to threat mitigation, where possible or practical.
Pole mounted electrical equipment such as transformers, capacitors, switches, etc. should be provided
at least ten (10) feet of clearance in accordance with the UPZ.
Secondary conductors should be cleared such that tree limbs do not rub conductors or entangle the
wire.
Remove hazard trees within the UPZ and on private property after obtaining written consent from the
abutting private property owner.
Pruning cuts shall be performed in a manner that retains the structural integrity and health of the
vegetation.
Consideration shall be given to critical loads and the number of customers served by the circuit
segment where tree work is performed.
No UPZ tree work shall be performed (pruning or removal) within the public right-of-way without a
permit from the municipal tree warden or the State Commissioner of Transportation.
Any non-hazardous tree located in whole or in part within the UPZ may be retained, provided that its
species, condition and growth rate indicate that pruning without removal will reduce the risk of harm
to the utility infrastructure.
Written consent shall be obtained from the tree owner to prune or remove a tree on private property.
“Brush” is de ined as an undesirable woody plant normally maturing at 20 feet or more in height, with
single or multiple stems, and with a small, minimal, or no crown. It shall have a diameter at breast
height (DBH, 4.5 feet above ground) of 6 inches or less. Brush shall be cut to the ground line where
topography and obstructions will permit.
Vines shall be removed from down guys and poles. If vines are in contact with energized wires, the
worker while in an aerial lift shall cut out a section of the vine stem measuring approximately one (1)
foot in length starting at a point approximately 30 inches below the lowest electric wire. Then, the
worker shall ground cut the vine(s) a minimum 5 feet from pole or down guy.
Street Lights – The local municipality is responsible to perform routine maintenance trimming to
maintain street light patterns on sidewalks and roadways. Con licts with energized lines shall be
referred to UI by the municipality. Limbs in direct contact with street light mast or head shall be
pruned clear to reduce possibility of equipment damage.
Private Area Lights – During routine maintenance, pruning should clear any vegetation on the pole
which is obstructing the pole-mounted ixture.
C. Substation Vegetation Maintenance Requirements
Substation facilities are maintained year-round to ensure security and safety of workers and the
public. Trap rock within the fenced-in and energized areas must always be kept free of vegetation.
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