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Proposed Rule

Specifications for Primary Underground Power Cable

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Rural Utilities Service, USDA.


Proposed rule.


The Rural Utilities Service, an agency delivering the United States Department of Agriculture's (USDA) Rural Development Utilities Programs, hereinafter referred to as Rural Development and/or the Agency, proposes to amend its regulations regarding Bulletin 50-70 (U-1) for electric distribution specifications for 15 kV and 25 kV primary underground power cable. This proposed rule is necessary to provide Agency electric borrowers with updated specifications for 15 kV and 25 kV underground power cable, and to provide borrowers with specifications for 35 kV underground power cable for use in 25 kV primary systems. These specifications cover single-phase and multi-phase primary underground power cable which Agency electric borrowers use to construct their rural underground electric distribution systems.


Written comments must be received by the Agency or bear a postmark or equivalent no later than October 29, 2007.


Submit adverse comments or notice of intent to submit adverse comments by any of the following methods:

  • Federal eRulemaking Portal: Go to and, in the lower “Search Regulations and Federal Actions” box, select “Rural Utilities Service” from the agency drop-down menu, then click on “Submit.” In the Docket ID column, select RUS-07-Electric-0009 to submit or view public comments and to view supporting and related materials available electronically. Information on using, including instructions for accessing documents, submitting comments, and viewing the docket after the close of the comment period, is available through the site's “User Tips” link.
  • Postal Mail: Addressed to Michele L. Brooks, Acting Director, Program Development and Regulatory Analysis, USDA Rural Development, Utilities Programs, U.S. Department of Agriculture, 1400 Independence Avenue, SW., STOP 1522, Washington, DC 20250-1522.
  • Hand Delivery/Courier: Addressed to Michele L. Brooks, Acting Director, Program Development and Regulatory Analysis, USDA Rural Development, U.S. Department of Agriculture, 1400 Independence Avenue, SW., Room 5168 South Building, Washington, DC 20250-1522.

Instructions: All submissions received must include the agency name and the subject heading “Primary Underground Power Cable.” All comments received must identify the name of the individual (and the name of the entity, if applicable) who is submitting the comment. All comments received will be posted without change to​rus/​index2/​Comments.htm, including any personal information provided.

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Mr. Trung V. Hiu, Electrical Engineer, Electric Staff Division, Distribution Branch, Utilities Program, USDA Rural Development, U.S. Department of Agriculture, Room 1262-S, 1400 Independence Avenue, SW., Washington, DC 20250-1569. Telephone: (202) 720-1877. Fax: (202) 720-7491. E-mail:

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Executive Order 12866

This proposed rule is exempted from the Office of Management and Budget (OMB) review for purposes of Executive Order 12866 and, therefore, has not been reviewed by OMB.

Executive Order 12372

This proposed rule is excluded from the scope of Executive Order 12372, Intergovernmental Consultation, which may require consultation with State and local officials. A notice of final rule entitled “Department Programs and Activities Excluded from Executive Order 12372,” (50 FR 47034) exempted USDA Rural Development Utilities Program loans and loan guarantees to from coverage under this order.

Executive Order 12988

This proposed rule has been reviewed under Executive Order 12988, Civil Justice Reform. USDA Rural Development has determined that this proposed rule meets the applicable standards provided in section 3 of the Executive Order. In addition, all state and local laws and regulations that are in conflict with this rule will be preempted. No retroactive effect will be given to this rule and in accordance with section 212(e) of the Department of Agriculture Reorganization Act of 1994 (7 U.S.C. 6912(e)) administrative appeal procedures, if any, must be exhausted before an action against the Department or its agencies may be initiated.

Executive Order 13132

This proposed rule will not have substantial direct effects on the States, on the relationship between the national government and the States, or on distribution of power and responsibilities among the various levels of government. Under Executive Order 13132, this rule does not have sufficient federalism implications to require preparation of a Federalism Assessment.

Regulatory Flexibility Act Certification

USDA Rural Development has been determined that the Regulatory Flexibility Act is not applicable to this rule since USDA Rural Development is not required by 5 U.S.C. 551 et seq. or any other provision of the law to publish a notice of proposed rulemaking with request to the subject matter of this rule.

Information Collection and Recordkeeping Requirements

This proposed rule contains no additional information collection or recordkeeping requirements approval under the Paperwork Reduction Act of 1995 (44 U.S.C. Chapter 35).

Catalog of Federal Domestic Assistance

The program described by this proposed rule is listed in the Catalog of Federal Domestic Assistance Programs under No. 10.850, Rural Electrification Loans and Loan Guarantees. This Start Printed Page 50082catalog is available on a subscription basis from the Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402-9325, telephone number (202) 512-1800.

Executive Order 12372

This proposed rule is excluded from the scope of Executive Order 12372, Intergovernmental Consultation, which may require consultation with State and local officials. See the final rule related notice titled “Department Programs and Activities Excluded from Executive Order 12372” (50 FR 47034), advising that USDA Rural Development Utilities Programs loans and loan guarantees are excluded from the scope of Executive Order 12372.

Unfunded Mandates

This proposed rule contains no Federal Mandates (under the regulatory provision of title II of the Unfunded Mandates Reform Act of 1995 [2 U.S.C. Chapter 25]) for State, local, and tribal governments or the private sector. Thus, this proposed rule is not subject to the requirements of sections 202 and 205 of the Unfunded Mandates Reform Act of 1995.

National Environmental Policy Act Certification

USDA Rural Development has determined that this proposed rule will not significantly affect the quality of the human environment as defined by the National Environmental Policy Act of 1969 (42 U.S.C. 4321 et seq.). Therefore, this action does not require an environmental impact statement or assessment.


Pursuant to the Rural Electrification Act of 1936, as amended (7 U.S.C. 901 et seq.), the Agency is proposing to amend Title 7 CFR Chapter XVII, Part 1728, Electric Standards and Specifications for Materials and Construction, by revising RUS Bulletin 50-70 (U-1), “Specifications for 15 kV and 25 kV Primary Underground Power Cable.” This revised bulletin will be renumbered and renamed Bulletin 1728F-U1, “Specification for Primary Underground Power Cable.” The proposed action would continue to incorporate the revised bulletin by reference in 7 CFR 1728.97 and RUS Bulletin 50-70 (U-1) would be rescinded and removed from the list in 7 CFR 1728.97. The change in the bulletin number and reformatting is necessary to conform to current publications and directives system. The Agency maintains a system of bulletins that contain construction standards and specifications for materials and equipment which must be complied with when system facilities are constructed by electric and telecommunications borrowers in accordance with the loan contract. These standards and specifications contain standard construction units and material items and equipment units commonly used in electric and telecommunications borrowers' systems.

Bulletin 50-70 (U-1) provides standard requirements for 15 kV and 25 kV single-phase and multi-phase primary underground power cable with cross-linked polyethylene with tree retardant or ethylene propylene rubber insulation, concentric neutral, and insulating outer jacket. The Agency proposes to update the specifications for 15 kV and 25 kV primary underground cable while adding specifications for 35 kV primary underground power cable.

The following changes and updating of Bulletin 50-70 (U-1) are proposed:

1. Water blocking sealant would be required in all stranded conductor cables.

2. The plain cross-linked polyethylene (XLP) would be removed and be replaced by tree-retardant cross-linked polyethylene (TR-XLPE) as an acceptable insulation material.

3. Nominal insulation thickness on 25 kV cable would be reduced from 345 mils to 260 mils.

4. An optional semi-conducting jacketing material would be added to the specification for cables of all three specified voltages. Cables with semi-conducting jackets may be used by USDA Rural Development borrowers in areas with soil resistivity greater than 25 ohm-meter, in lieu of using cables with an insulating jacket to help improve the effectiveness of system grounding in locations of high soil resistivity.

The following table summarizes all of the changes and contains a cross walk between the format of the current bulletin and the new proposed bulletin:

RUS Specifications for Primary Underground Power Cable

[Summary of proposed changes]

Existing section Bulletin 50-70 (U-1) (old numbering system)Proposed new location Bulletin 1728F-U1 (new numbering system)Action takenProposed content change
N/A1.a SummaryNew additionIdentifies new title and number for REA Bulletin 50-70(U-a) and updates the superseded reference.
N/A1.b Principal RevisionsNew additionLists the principal changes made in the reissued and renumbered bulletin.
1.1.1 Scope2.a General SpecificationsModifiedStates the revised scope to add 35 kV rated cable and semiconducting jacket to the existing 15 and 25 kV specifications. Removes XLPE as an acceptable insulation material. Removes reference to 13.2/7.62 kV power cables.
1.1.22.bNo change
1.1.32.cModifiedAdds conductor size for 35 kV cable.
1.1.42.dModifiedUpdates reference to the renamed industry standard reference for material specifications (this comment pertains to all such references throughout Bulletin 1728F-U1).
1.1.52.dNo substantive changeUpdates reference to renamed industry standard references.
2.3.aModifiedUpdates references to renamed industry standard references for material specifications. Incorporates additional material specifications added to the industry standard reference since the last publication of this bulletin.
N/A3.b(1), b(2)NewProvides information to reader on where to obtain industry standard references incorporated in this bulletin.
3.3.14.aNo change
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3.3.24.bModifiedAdds combination unilay stranded phase conductors.
3. 3.2.14.bModifiedAdds combination unilay stranded phase conductors. change compact round concentric-lay-stranded phase conductors and combination unilay stranded aluminum phase conductors.
3.3.44.c(3)ModifiedChanges the acceptable filler for interstices between strands of stranded conductors from “conductive” material to “material designed to fill the interstices,” adds requirement that the surfaces of the strands that form the outer surface of the stranded conductor shall be free of the fill material. Adds testing requirement for compatibility of the strand fill material and water penetration.
N/A4.c(4)AddedRequires the solid conductor and center strand of stranded conductors to be indented at fixed interval with the name of manufacturer and year of manufacture.
4.4.15.aNo substantive change, 5.1.2, 5.1.36.aModifiedRemoves XLPE as an acceptable insulation material. Conforms references to industry standard references.
5.26.bModifiedMaintains 220 mils as the nominal allowed insulation thickness on 15 kV cable, reduces the allowed insulation nominal thickness from 345 mils to 260 mils on 25 kV cable and establishes nominal insulation thickness of 345 mils on 35 kV cable.
6.6.17.aNo change
6.6.2DeletedRemoves specific test requirement for sunlight exposure and atmospheric conditions. There is no current test reference available.
6.6.37.bNo change
6.6.47.cModifiedSpecifies specific stripping tension values in lieu of cross referencing industry standards.
6.6.57.dNo change
7.7.18.aModifiedAdds requirement that concentric neutral wires shall remain in continuous intimate contact with the extruded insulation shield.
7.7.38.aAdds full neutral requirement for single phase and 1/3 neutral requirement for three phase applications. Establishes minimum wire size of 16 AWG for the concentric neutral.
7.7.48.bNo substantive change
8.8.19.aModifiedAdds semi-conducting outer jacket. substantive changeAdds requirement that the jacket material shall have three red stripes longitudinally extruded into the jacket surface 120 degrees apart. substantive changeAdds medium density and high density HMW black polyethylene compound. Specifies that polyvinyl chloride (PVC) and chlorinated polyethylene (CPE) jackets are not acceptable.
8.39.bNo change
9.110.No change
10.111.aNo substantive change
10.1.111.a(1)No change
10.1.211.a(2)No change
10.1.311.a(3)No change
10.211.bNo substantive changeEliminates affirmative requirements to submit data to REA.
10.2.111.b(1)No change
10.2.211.b(2)No change
10.311.cModifiedClarifies that the tests in this section 11c are to be performed on cable jackets from the same production sample as is subjected to tests specified in section 11b.
10.3.111.c(1)No change
10.3.211.c(2)ModifiedPrescribes the same test voltage (4.5kV AC) for cable diameters less than or equal to 1.5 inches and sets a test voltage of 7.0 kV for cable diameters greater than 1.5 inches.
10.411.dNo change
10.5DeletedRemoves measurement requirement that is implicit in other sections of the bulletin.
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10.611.eAddedAdds provision that certified copies of all tests results performed pursuant to this renumbered section 11 shall be provided on request of the borrower for all orders.
11.112.aModifiedClarifies with greater specificity markings that are considered suitable on the outer surface of the jacket.
11.212.bModifiedAdds requirement that each end of the cable shall be firmly and properly secured to the reel.
N/A12.cAddedAdds requirement that reels are to be covered with a suitable covering to help protect the cable.
11.312.dNo substantive changeProvides that the beginning and ending sequential footage numbers are to be included on the label regardless of whether they are marked on the cable jacket.
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List of Subjects in 7 CFR Part 1728

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For the reasons set out in the preamble, 7 CFR part 1728 is proposed to be amended as follows:

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1. The authority citation for part 1728 continues to read as follows:

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Authority: 7 U.S.C. 901 et seq., 7 U.S.C. 1921 et seq.; 7 U.S.C. 6941 et seq.

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2. Section 1728.97(b) is amended by removing the entry for RUS Bulletin 50-70, and adding to the list of bulletins, in numerical order, the entry for Bulletin 1728F-U1 to read as follows:

Incorporation by reference of electric standards and specifications.
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(b) List of bulletins.

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Bulletin 1728F-U1, Specifications for Primary Underground Power Cable, [Insert month and year of effective date of final rule].

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Dated: August 23, 2007.

James M. Andrew,

Administrator, Rural Utilities Service.

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[FR Doc. E7-17194 Filed 8-29-07; 8:45 am]