O R D E R

IT IS ORDERED that:

This order is effective today.

Dated January 23, 1997, at San Francisco, California.

P. GREGORY CONLON
President
JESSIE J. KNIGHT, JR.
HENRY M. DUQUE
JOSIAH L. NEEPER
RICHARD A. BILAS
Commissioners

PROPOSED RULE 35

35. Tree Trimming

Where overhead wires pass through trees, safety and reliability of service demand that tree trimming be done in order that the wires may clear branches and foliage by a reasonable distance. The minimum clearances established in Table 1, Case 13, measured between line conductors and vegetation under normal conditions, shall be maintained. (Also see Appendix E for tree trimming guidelines).

When a utility has actual knowledge, obtained either through normal operating practices or notification to the utility, dead, rotten, and diseased trees or portions thereof, that overhang or lean toward and may fall into a span, should be removed.

Communication and electric supply circuits, energized at 750 volts or less, including their service drops, should be kept clear of limbs and foliage, in new construction and when circuits are reconstructed or repaired, whenever practicable. When a utility has actual knowledge, obtained either through normal operating practices or notification to the utility, that any circuit energized at 750 volts or less shows strain or evidences abrasion from tree contact, the condition shall be corrected by slacking or rearranging the line, trimming the tree or placing mechanical protection on the conductor(s).

Exceptions:

PROPOSED RULE 37

37. Minimum Clearances of Wires Above Railroads, Thoroughfares, Buildings, etc.

Clearances between overhead conductors, guys, messengers or trolley span wires and tops of rails, surfaces of thoroughfares or other generally accessible areas across, along or above which any of the former pass; also the clearances between conductors, guys, messengers or trolley span wires and buildings, poles, structures, or other objects, shall not be less than those set forth in Table 1, at a temperature of 60`F. and no wind.

The clearances specified in Table 1, Case 1, Columns A, B, D, E, and F, shall in no case be reduced more than 5% below the tabular values because of temperature and loading as specified in Rule 43. The clearances specified in Table 1, Cases 2 to 10 inclusive, shall in no case be reduced more than 10% below the tabular values because of temperature and loading as specified in Rule 43.

The clearances specified in Table 1, Case 1, Column C (22 1/2 feet), shall in no case be reduced below the tabular value because of temperature and loading as specified in Rule 43.

The clearances specified in Table 1, Cases 11, 12, and 13, shall in no case be reduced below the tabular values because of temperatures and loading as specified in Rule 43.

Where supply conductors are supported by suspension insulators at crossings over railroads which transport freight cars, the initial clearances shall be sufficient to prevent reduction to clearances less than 95% of the clearances specified in Table 1, Case 1, through the breaking of a conductor in either of the adjoining spans.

Where conductors, dead ends, and metal pins are concerned in any clearance specified in these rules, all clearances of less than 5 inches shall be applicable from surface of conductors (not including tie wires), dead ends, and metal pins, except clearances between surface of crossarm and conductors supported on pins and insulators (referred to in Table 1, Case 9) in which case the minimum clearance specified shall apply between center line of conductor and surface of crossarm or other line structure on which the conductor is supported.

All clearances of 5 inches or more shall be applicable from the center lines of conductors concerned.

PROPOSED APPENDIX E

APPENDIX E

The following are guidelines to Rule 35.

The radial clearances shown below are minimum clearances that should be established, at time of trimming, between the vegetation and the energized conductors and associated live parts where practicable. Vegetation management practices may make it advantageous to obtain greater clearances than those listed below:

A. Radial clearance for any conductor of a line operating at 2,400 or more volts, but less than 72,000 volts ............................... 4 feet

B. Radial clearance for any conductor of a line operating at 72,000 or more volts, but less than 110,000 volts .............................. 6 feet

C. Radial clearance for any conductor of a line operating at 110,000 or more volts, but less than 300,000 volts .............................. 10 feet

D. Radial clearance for any conductor of a line operating at 300,000 or more volts .............. 15 feet

(END OF APPENDIX)

(1) The standards proposed for consideration are those contained in "Proposed Rule 35, Proposed Rule 37, Proposed Change to Table 1, and Proposed - Appendix E", which comprise pages 12 through 15 of Appendix C to D.96-09-097. The rest of the Settlement is immaterial, as D.96-09-097 approved and adopted it in its entirety pursuant to Rule 51. Therefore, it is the sponsoring parties' agreement to propose these specific changes to G.O. 95 to which we are responding in this decision by taking the further step of acting upon the proposal.

(2) Rule 37 is titled, "Minimum Clearances of Wires Above Railroads, Thoroughfares, Buildings, Etc." Table 1 bears the title, "Basic Minimum Allowable Vertical Clearance of Wires Above Railroads, Thoroughfares, Ground or Water Surfaces; Also Clearances from Poles, Buildings, Structures or Other Objects [note omitted]." Adding Case 13 to this table under Rule 35 is apparently suggested as an expedient method for articulating minimum clearances between any overhead wires and neighboring vegetation. Caveat, however, that the note to the title states, "Voltage shown in the table shall mean line-to-ground voltage for direct current (DC) systems." All standards adopted here must be understood to apply as well to alternating current (AC) systems, which comprise the state's transmission and distribution system.

(3) The text of Appendix E also observes that vegetation management practices may make it advantageous to obtain greater clearances than those listed.

(4) In the latter instance, the proposed rule nevertheless expressly recognizes that the utility may be directed by this Commission to take prompt remedial action.

(5) Rule 14.1 defines a Commission rulemaking as "a formal Commission proceeding in which written proposals, comments, or exceptions are used instead of evidentiary hearings." Applying this standard, the procedure we have followed is almost exactly that which would have been followed in a rulemaking proceeding.

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