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Home > Contractors & Developers > Customer Service > Meter Specification Manual > Chapter 7

Meter Specification Manual

 

Chapter 7 - UNDERGROUND SERVICES (RESIDENTIAL
SINGLE FAMILY RESIDENTIAL, DUPLEXES, OR TOWNHOUSES

 

7.01 GENERAL

Also refer to Chapter 3 (Service Entrances), and Chapter 4 (Meter Installations).
OPPD will install, own, and maintain the underground service lateral and metering equipment in accordance with OPPD's applicable rates and extension rules and the requirements of Chapters 1, 2, 3, and 4, except:
  • The customer is required to provide and install the underground residential service lateral. If cable is larger than 350 KCMIL, aluminum is required.
  • Customer metering is located on padmounted transformer, (as mentioned below).
  • OPPD cannot install an underground service due to physical conditions, (where there is a shelf of rock beneath the soil surface, or densely wooded areas).
  • If the residence is served at other than the Residential rate.
Underground service lateral is defined as the underground service conductors from the last pole, pedestal, transformer, or other OPPD serving equipment, which runs to, and is connected to the customer's meter socket or current transformer metering at the customer’s building or structure.

The customer shall install, own, and maintain all service entrance facilities other than the service lateral and metering equipment, regardless of metering location.

The customer shall make application to OPPD for the proposed underground service lateral and obtain approval of the location before starting installation of the service entrance. Any required, non-refundable, charges must be paid to OPPD before the service drop is installed.

Metering on Padmounted Transformer

If a residential customer has the metering on a padmounted transformer, installed for their sole use, the customer is required to provide, install, and maintain their own underground service cables to the residence. They should therefore follow the instructions of Chapter 8, which is for General Service underground services. This is necessary, since OPPD is not responsible for wiring which is down-stream of the metering.

Meter-Disconnect Combination on an Existing Home with a New Addition

In the case of an existing single family residence, where the customer is adding an addition, which will enclose the POE and meter socket, a combination meter socket-disconnect may be used. The combination meter socket-disconnect shall be provided, installed, and maintained by the customer at a new POE, designated by OPPD’s ESD, on the new addition. This will allow the customer to comply with the NEC requirement for a disconnect switch, when electrical conductors enter a building (the new addition), and feed to the existing distribution panel in the existing part of the house.

The combination meter socket-disconnect must meet the following requirements:

  • There must be a separate cover for both the meter socket and disconnect (breaker) compartment. Either cover must be able to be removed without disturbing the other cover.
  • The meter socket cover must be of ring-less design, and have a provision for the meter seal. OPPD reserves the right to lock the meter socket cover, in any manner, to insure the security of the socket and meter.
  • The meter socket line-side lugs must be able to accept up to 250 KCMIL copper or aluminum conductors.
  • The meter socket must have a 2½ inch knockout, for a breaker rated up to 200 amps, or a 3 inch knockout, for a breaker rated up to 400 amps. This knockout must be located on the bottom panel of the meter socket on either the right or left side, and will be used for the installation of the incoming riser pipe and service conductors. The disconnect must be located so as not to interfere with the installation of the service conductors and riser pipe into the bottom of the socket.
  • OPPD’s service conductors must be separated from the customer’s load conductors by a permanent barrier.
Any other use of the combination meter socket-disconnect must be approved by the Manager- Metering Services, 552-5934, on an individual basis, prior to installation.
 

7.02 SERVICE LATERAL REQUIREMENTS

Trenchable Cable Path

OPPD will not install underground extensions, or service laterals, across rock quarries, or other locations not suitable for underground cables and equipment.

The service lateral will be installed only after grade levels, and other cable path conditions, are found satisfactory by OPPD. The customer shall clear a cable route for OPPD use, free of trees and other obstacles at his own expense. OPPD crews will not move obstacles such as dirt piles, lumber, rubble, tree branches, or tall weeds. An 8' wide path will generally be sufficient for a straight run of trenching, but a larger area may be needed where the trench changes direction, for OPPD to maneuver and turn a medium sized tractor-trencher. The customer may be required to install a schedule 40 PVC conduit for the service lateral, at 24” minimum depth below finish grade, measured to the top of the conduit. This would be necessary where the customer cannot provide the needed clear areas for OPPD equipment to maneuver, or access, (such as a ledge area between a house and a wall, or drop-off). Where mature trees are involved along the cable route, a larger clear path may be required due to the need to avoid tree roots while trenching. The trench path must be to within 6 inches of final grade.

OPPD is not responsible for repair of any damage to lawn sprinkler systems, sod, grass-seed, trees or shrubbery (or similar items) when installing, or maintaining the underground service.

Easements

The customer shall provide an easement, when required, at no expense to OPPD for the installation and maintenance of the service lateral. No permanent building or tree shall be placed over the service lateral, or on this easement. No swimming pool, hot tub, or wading pool shall be installed over, or within 5 feet of the service conduit, or cables.

Grade Changes

If later changes in grade levels reduce the depth of cover over cables or require equipment relocation, the customer must notify OPPD before grading, and pay the entire cost of grading or filling, as well as any subsequently-required cable or equipment relocation or replacement by OPPD. A similar situation may arise from the customer increasing the depth of ground cover above or near to, OPPD's cables, or equipment. For the location of OPPD-owned cable, the customer should contact the "Digger's Hotline of Nebraska" before digging. See Section 1.14 for the telephone number.

Conduit

Where grade changes or obstacles, such as decks, patios, retaining walls or ledges, prevent OPPD from trenching in the underground service conductors, the customer shall be required to provide a schedule 40 PVC conduit for the conductors to a clear point beyond the obstacle as directed by OPPD. The conduit shall be 2½" for a 200 amp service, or 3" for a 320 amp service.

Retaining Walls

If a retaining wall interferes with the intended cable path on the customer’s property, the customer will install a schedule 40 PVC conduit for the service cables, as shown on drawing 7.02.1.

OPPD Unable to Trench

If the area along the intended cable path, between the home and the retaining wall is 20 feet or less, is hard-surfaced, or is inaccessible to OPPD trenching equipment, the builder, or his electrician is required to install a schedule 40 PVC conduit. The conduit is to be placed between a minimum of 24" and a maximum of 30" below final finish grade, measured to top of conduit.

Future Inability to Trench

If the area is now accessible for OPPD trenching, but in the future is to be paved, hard surfaced, or will have structures such as decks, patios, or retaining walls put on it, the customer is also required to install a conduit for OPPD use.

Post-Installation Problems

In the case of placement of any of the above-mentioned obstructions to a clear trenching path over an existing service cable, followed by failure of the cable, the customer must provide and install a correctly-sized conduit before OPPD can restore permanent service by replacing the failed service cables.

Conduit Adjacent to the Riser Pipe

If conditions require the installation of a conduit adjacent to the meter riser, the customer is responsible for purchasing and installing all necessary material, including the meter socket, conduit, slip-joint riser and 36" minimum radius 90-degree bend, as shown in drawing 7.02.2.

Care should be taken to sleeve around the riser pipe, so the hard-surfacing material does not grip and constrict movement of the riser pipe. The sleeve should accommodate a 2 ½" conduit for a 200 amp meter socket riser, or a 3" conduit for a 320 amp meter socket riser. See drawing 7.02.2 for details.

Conduit Adjacent to OPPD Equipment

If the customer’s conduit ends near OPPD equipment, the conduit is to be ended between 3 to 6 feet distance away from OPPD’s serving equipment, and any adjacent OPPD underground cables. OPPD will extend cables from the serving equipment into the conduit.

Customer’s Meter Support

If a customer elects not to provide a trenchable cable path, or install a conduit, he also has the option to install the meter on a suitable support, supplied by the customer, adjacent to OPPD's facilities at the property line. The customer can accept service there, and run their own buried conductors from the meter to their home. A disconnect, although it may not be required by the current NEC, is recommended, for protection of the customer's buried conductors between the meter and the residence, in this situation. A typical customer meter support installation is shown in drawing 7.06.

 

7.03 CONNECTIONS

OPPD will connect the underground service cables to the customer's metering equipment, (either the socket lugs, or the CT’s in a cabinet).
 

7.04 CLEARANCES

To avoid damage to OPPD facilities when the customer may be digging, the underground service lateral shall have a minimum horizontal clearance of 6 feet from swimming pools, fuel storage tanks, septic systems, etc.

A minimum 2’-6” working clearance above, below, and on all sides of the meter socket, or metering enclosures, as well as 3’ horizontally in front of the metering shall be maintained at all times.

For single residential underground meter sockets, the socket shall be mounted no higher than 4' above finished grade to the bottom of the meter socket for a 200 amp socket. For a 320 amp socket, the socket shall be mounted no higher than 3'-6" above finished grade to the bottom of the meter socket, to facilitate reading without need of a ladder or raised platform. In addition, for both a 200 amp socket and a 320 amp socket, the bottom of the meter socket shall not be installed lower than 2’-6" from the bottom of the socket down to finished grade. This is done to provide sufficient space to install the slip-fit riser pipe down from the bottom of the socket to below grade level.

If the metering location is under a deck or similar structure, the minimum clearance between the deck bottom and finish grade must be 6 foot, 6 inches to allow access for meter reading without having to stoop or crawl.

Cantilevers

If the meter socket is installed on a cantilever, the riser pipe shall be backed by a 4 x 4 treated wood post, securely fastened to the house, and buried a minimum of 18” below grade. This will provide physical protection for the pipe from either damage, or dislocation. (See drawing 7.04.1).

If the meter socket is installed under the cantilever, the cantilever must be a minimum of 6’-6” above grade. This will provide sufficient height above the meter socket for working clearance, and below the meter socket to provide sufficient length for installation of the slip-fit riser pipe. (See drawing 7.04.2).

Brick Ledge

In the case where the residence wall has a protruding brick ledge, the customer is to install the socket out from the wall with an adequate support, so the riser pipe clears the brick ledge.

 

7.05 UNDERGROUND SERVICE TO SINGLE OR DUPLEX METER SOCKET

SINGLE-PHASE 100 through 320 AMPS, 240 VOLTS AND UNDER

See drawings 7.05.1, 7.05.2, and 7.05.3.

Also see Section 4.02 for socket detail drawings.

OPPD furnishes, installs, and maintains: ○

1.     A single underground service lateral.

2.     Socket-type meter.

The Customer installs, provides and maintains: ∆

3.     A slip-joint riser pipe assembly: Schedule 80 PVC, 2 ½” for a 200 amp service or 3 “ for a 320 amp service.

4.    The meter socket.
5.    ½” x 8’ copper clad supplemental ground rod per current “National Electrical Code”.

6.    Continuous copper ground wire, not less than #6 AWG, from ground rod to meter socket.

 7.     When hard surfacing is to be over the cable path, adjacent to the meter location, OPPD requires a conduit under the hard surfacing, up to the riser pipe, and a 36” minimum radius bend of the proper size, connected to the slip-joint riser pipe. The conduit should be sleeved as it passes through the hard surfacing, to allow for freedom of movement of the riser. (See drawing 7.02.2.)

NOTE:

A.    Minimum working clearances as required by NEC 110.26 shall be provided and maintained by the customer at all times. OPPD requires a minimum of 2’-6” of side clearance on all metering equipment.

 

7.06 FREE-STANDING SUPPORT FOR UNDERGROUND SERVICE ENTRANCE

100 through 200 AMP, or 320 AMP - 240 VOLTS AND UNDER
Refer to Chapter 9 for mobile homes.

Refer to drawing 7.06.

The customer shall consult with OPPD before this installation is planned or started, to determine availability.

Where no building or structure is available, the customer shall install a freestanding support for OPPD's meter, and for terminating OPPD's underground service lateral. Support posts must be 4 X 4 treated wood, galvanized pipe, or metal channel suitable for earth contact and set in concrete. Height of the support must be such as to provide for the mounting of the bottom of the meter socket between 2'-6" minimum and a maximum of 4' above finished grade for a 200 amp socket. The support must provide for the mounting of the bottom of the meter socket between 2'-6" minimum and a maximum of 3'-6" above finished grade for a 320 amp socket.

OPPD furnishes, installs, and maintains: ○

1.    Underground service lateral to the meter socket.

2.    Socket type meter.

The customer furnishes, installs and maintains: ∆
3.    The meter socket.

4.    A slip-joint riser pipe assembly: 2 ½” for a 200 amp service or 3 “ for a 320 amp service.

5.    The support structure.

6.    ½” x 8’ copper clad supplemental ground rod per current “National Electrical Code”.

7.    Continuous copper ground wire, not to be less than a #6 AWG, from ground rod to meter socket.

 8.    When hard surfacing is to be over the cable path, adjacent to the meter location, OPPD requires a conduit under the hard surfacing, up to the riser pipe, and a 36” minimum radius bend of the proper size, connected to the slip-joint riser pipe. The conduit should be sleeved as it passes through the hard surfacing, to allow for freedom of movement of the riser. (See drawing 7.02.2.)

NOTE:

A. A minimum clear working space of 2’-6” above, below and on both sides of the metering enclosure, for working clearance, as well as 3 feet horizontally in front of the metering, shall be provided and maintained, by the customer, at all times.

 

7.07 UNDERGROUND SERVICE TO CT CABINET

SINGLE-PHASE, 400 through 800 AMP - 120/240 VOLTS
Refer to Section 4.06 for CT metering requirements.
Refer to Section 6.11 for General Service and Residential overhead CT installation details.
Refer to Section 8.06 for General Service underground CT installation details.

See drawing 7.07 & 4.06.3.

OPPD furnishes, installs, and maintains: ○

1.    Underground service lateral, unless the conductors are larger than 350 KCMIL aluminum. The customer provides all conductors larger than 350 KCMIL aluminum.

2.    Meter and instrument wiring (see Chapter 4)
 

OPPD furnishes, and the customer installs, and maintains: □
 
3.    Current transformers. For lug connections on current transformers up to 600 amperes, minimum bolt size is 3/8”. For over 600 amperes, minimum bolt size is ½”. Two-hole lugs are required, and one-hole lugs are not allowed.

4.    Meter socket for CT application.
 

The Customer furnishes, installs, and maintains: ∆
 
5.    A riser pipe sized for the conductors, per the NEC.

6.    Metering transformer cabinet (see Chapter 4). Customer is to furnish “National Electrical Code” grade steel cabinet of adequate size for the instrument transformers and all wiring connections.

7.    ½” x 8’ copper clad supplemental ground rod per current “National Electrical Code”.

8.    Continuous copper ground wire, not less than a # 6 AWG, from ground rod to meter socket.

9.    Conduit, when required, below grade for underground conductors located under concrete, patios, decks, retaining walls, grade changes, or other obstructions that do not provide OPPD with a clear trenching path for installation. (See Paragraph 7.02.)

10.  1” conduit from instrument cabinet to meter socket.

11.  Two-hole line-side lugs and the load side lugs.

NOTES:

A.    The customer shall consult OPPD before this installation is planned or started.

B.    T-condulet conduit bodies are not permitted in the conduit run containing the customer's underground service conductors ahead of the meter.

C.    A minimum 3’ clear working space must be provided in front of the metering transformer cabinet to allow for full door opening. In addition, a minimum 2’-6” clear working space must be provided and maintained above, below, and on all sides of the metering transformer cabinet.

 

7.08 REQUIREMENTS FOR PRIMARY AND SECONDARY CABLES AND EQUIPMENT ON LARGE LOT RESIDENTIAL PRIVATE PROPERTY (ACREAGES)

For one, and two unit residences, OPPD installs, owns, and maintains an underground service lateral to a suitable point of termination on the customer's premises. This is in accordance with OPPD’s applicable extension rules, except as mentioned in Section 1.03.1.C, (meter on padmounted transformer), and for large services, (where the required conductor size exceeds 350 KCMIL aluminum). OPPD will specify the installation and service requirements, and will designate the location of OPPD's equipment, from which a customer is to be served, as well as the POE on the residence.

OPPD will not install underground extensions or service laterals across rock quarries or other locations not suitable for underground cables and equipment.

Trenchable Cable Path

The customer shall clear a cable route for OPPD use free of trees and other obstacles at their own expense. OPPD crews will not move obstacles such as dirt piles, lumber, rubble, tree branches, or tall weeds. An 8 foot wide path shall generally be sufficient for a straight run of trenching, but a larger area may be needed where the trench changes direction, to maneuver and turn a medium sized tractor-trencher. Where mature trees are involved along the cable route, a larger clear path may be required due to the need to avoid tree roots while trenching. The trench path must be within 6 inches of final grade.

Easement

The customer shall provide an easement, when required, at no expense to OPPD for the installation and maintenance of OPPD cable and equipment. No permanent building, structure, or tree shall be placed on this easement.

Grade Changes

If later changes in grade levels reduce the depth of cover over cables or require equipment relocation, the customer must notify OPPD before grading, and pay the entire cost of grading or filling, as well as any subsequently-required cable or equipment relocation or replacement by OPPD. A similar situation may arise from increasing depth of ground cover above or near to, OPPD's cables, or equipment. For the location of OPPD owned cable, contact the "Digger's Hotline of Nebraska" phone number before digging. See Section 1.14 for the telephone number.

Conduit

Where grade changes or obstacles prevent the customer from providing OPPD with a suitable cable path for trenching in the underground conductors, the customer shall provide a schedule 40 PVC conduit for the conductors to a clear point beyond the obstacle as directed by OPPD.

Retaining Walls

If a retaining wall is along the intended cable path on the customer’s property, the customer shall install a schedule 40 PVC conduit for OPPD’s cables, as shown on drawing 7.02.1.

Unable to Trench

If the area along the intended primary cable path is inaccessible to OPPD trenching equipment, the builder or his electrician shall install a schedule 40 PVC conduit. This primary conduit is to be placed a minimum of 42 inches below final finish grade measured to the top of the conduit.

Future Inability to Trench

If an area on the customer’s property is now accessible for trenching, but in the future is to be paved, hard surfaced, or will have structures such as decks, patios or retaining walls put on it, (so as to make future trenching for replacement or maintenance impossible for OPPD,) the customer is required to install a conduit for OPPD use. Consult with an ESD for the size of conduit required.

 

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