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6 Underground Requirements
Underground Requirements
(March 1, 2008) Electric Service Requirements
Portland General Electric (www.portlandgeneral.com)
37
6 Underground Requirements
6.1
Underground Service
The Customer is responsibile for the trenching, backfilling, compaction, conduit,
transformer pads or vaults, and any other requirements to complete the construction for
underground service. For transformer installations, the Customer must provide space
for the transformer. For all trenching and transformer installations, the customer must
meet any requirements of governmental authorities (including excavation permits) and
PGE.
Where exposed to motorized vehicles, the customer must install and maintain PGE
approved barriers to protect padmounted transformers and other equipment. (See
Figure 6-4
.)
In most cases, PGE will install, maintain, and own the underground service lateral from
PGEs distribution line or transformer to the point of delivery. No bends will be allowed
in the conduit riser between the meter base and the underground sweep. If local codes
do not allow conduit in the foundation and/or footings, a surface mounted meter must
be installed.
PGE will install conductors in Customer-provided conduit. A long sweep elbow is
required at the bottom of the service riser conduit in all cases.
Field heat bends are not acceptable. All bends must be factory made.
Refer to the
Table 6-1, (Minimum Conduit Required for Utility Conductors)
, for the
minimum conduit acceptable for PGE service lateral conductors. Contact PGE for
conduit requirements if primary voltage conductors are to be installed.
Where a Customers conduit extends vertically through a paved or concrete surface
adjacent to the service entrance, place a sleeve around the conduit to prevent direct
contact of the conduit with the pavement. This helps avoid damage to conductors and
service equipment caused by soil settling. (See
Figure 7-4
., note 2)
Where a Customers conduit extends to a PGE pole, the Customer must provide the
90-degree large radius sweep (see Table 6-1). Consult PGE for the exact location on
the pole. See
Section 6.3, Conduit
, for approved conduit material.
Cap all conduits at BOTH ends during installation to keep them free of dirt and
debris. All conduits must have a non-conductive pull line, 500 lb. rated, with 6
feet extending from each end.
All conduits shall be permanently attached along all conduit sections, including
couplings, adapters, sweeps, and termi-duct fittings, using either PVC glue or other
permanent mechanical joints.
The Customer is responsible for repairing, or the costs associated with repairing, any
conduit problems prior to the installation of PGE conductors. PGE will own and maintain
the conduit system once PGE conductors have been installed.
6.2
Trenches Provided by the Customer
PGE, in compliance with OSHA rules and OUCC standards, requires the spoils be kept
at least two feet away from the open trench when the trench is not shored. The
Customer must shore the trench when any combination of trench depth plus spoil
exceeds five feet. Also see
Section 7.2, Underground Service
. Electric Service Requirements (March 1, 2008)
Underground Requirements
38
Portland General Electric
The location of the service entrance on the Customers premises is an important
consideration to both the Customer and PGE. Customer responsibilities include: Consulting PGE to determine the route and the point of attachment for under-
ground service laterals, meter locations, service outlet locations, current trans-
formers, and terminal cabinet enclosures. Routing conduit under buildings or
other permanent obstructions should be avoided; exceptions may be allowed
with approval from PGE if alternative routes are not available. Special construc-
tion methods or materials may be required. Locating the service entrance to make the meter and service easily accessible
from PGE distribution lines and convenient for the installation, operation, and
maintenance of PGE meters and equipment. The Customer is responsible to recognize potential surface and subgrade water
flows that may allow the entry of water into the Customers electrical equipment.
PGE will coordinate with the Customer to assist in preventing this water entry. A permit from the local jurisdiction is required before any work in the
right-of-way may be performed. Only PGE approved excavation contractors and
contractors who have made other special agreements with PGE will be allowed
to work under PGEs permit. The contractor must notify the local jurisdiction 48
hours before the work is to begin. A copy of the permit must be on site.
6.2.1
Call Before You Dig
State laws require the Customer/Excavator to call for underground utility
cable locations at least two full working days (48 hours) prior to excavation.
The excavation must not be started until locations have been marked or the
utilities have informed the excavator that they have no facilities in the area.
Call 811 or 18003322344 before you dig. For Portland Metro call
503-246-6699. Website: www.digsafelyoregon.com
6.2.2
Service Trench
When installing only service cable in the trench, follow Service Trench
dimensions in
Figure 6-1
. When installing service cable with other
telecommunication utilities (telephone, cable T.V.) follow Joint Use Trench
Without Gas
Figure 6-2
or Joint Use Trench With Gas Figure 6-3.
6.2.3
Select Backfill
Trench depth shall include requirements for select backfill as necessary to
protect cables installed in rocky soil conditions. Figures 6-1, 6-2, and 6-3
provide select back fill depth requirements.
Select backfill are materials that pass through a 3/4 sieve and contain no
sharp or foreign objects. Underground Requirements
(March 1, 2008) Electric Service Requirements
Portland General Electric (www.portlandgeneral.com)
39
Figure 6-1 Service Trench
Figure 6-2 Joint Use Trench Without Gas
Backfill
Select Backfill
Undisturbed
Earth
Secondary cable
inside duct
LEGEND
36"
Min.
Trench
30"
Min.
Cover
10"
24"
Backfill
Undisturbed
Earth
Spoil
Typical
Refer to Notes after Fig 6-3.
Secondary & Telco/CATV
Secondary,Telco/CATV w/Gas
12Min
12
Min
Gas utilities
Telco/CATV
12 Min
Backfill
Select Backfill
Undisturbed
Earth
LEGEND
Refer to Notes after Fig 6-3.
Telco/CATV
PGE primary/
secondary cable
inside ducts
36"
Min.
Trench
30"
Min.
Cover
24"
Spoil Typical
10"
12"
Min
Contact Telco
for backfill
requirements
12" Min
42"
Min.
Trench
Utilities
Road Side
12 Min Electric Service Requirements (March 1, 2008)
Underground Requirements
40
Portland General Electric
Figure 6-3 Joint Use Mainline Trench
NOTES (Figures 6-1,6- 2 & 6-3):
1.
Where on-site backfill contains rocks larger than 4" and/or fractured rock (with sharp corners), select
backfill shall be used. Select backfill shall be placed a minimum of 4" below and 6" above the centerline of
the conduit/cable configuration, as shown. Select backfill material shall pass through a 3/4" sieve and
contain no sharp or foreign objects. Backfill in the remainder of the trench shall be free of rocks larger than
4" in diameter.
2.
The Customer is responsible for backfilling trenches and site restoration.
3.
Depths are min. depth; deeper trenches shall be required by designers for rocky & debris areas since sand
cushion will be needed under conductors.
4.
Water lines, on private property only, are allowed in trenches with a minimum of one foot vertical and one
foot horizontal separation from PGE conductors or conduits.
6.2.4
UNITY Service: Install Multiple Services
UNITY service is a joint effort between PGE and Northwest Natural that provides for
installation, including trenching and backfilling, of as many as four utilities in one ditch at one
time. UNITY is optional for phone and cable TV services. Contact PGE for further information
6.3
Conduit
The Customer shall install either rigid steel or electrical-grade Schedule 40 gray PVC conduit. Sweeps
of PVC, rigid steel, and fiberglass are acceptable. All PVC joints shall be glued. If rock or other
obstructions are encountered consult PGE. When the conduit terminates at a PGE pole, consult PGE
for exact conduit location.
Table 6-1
shows minimum conduit requirements.
Backfill
Select Backfill
Undisturbed
Earth
LEGEND
Refer to Notes below.
Telco/CATV
Utilities
PGE primary/
secondary cable
inside ducts
30"
Min.
Cover
Spoil Typical
12"
Min.
24"
Trench
Field Side
Gas Utilities
24"
12" Min
Road Side
48
Max
Trench
24