Change List for this Rule

 

General Order 95

 

Section V

 

Detailed Construction Requirements for Supply Lines
(Class H, L and T Circuits)

 

54.10    Low Voltage Multiconductor Cable with Bare Neutral, 0 - 750 Volts

 

A.    General

 

The following rules cover requirements for 0-750 volt bare neutral multiconductor cable (when used as line conductor) and are supplemental to the other rules of this order.

 

The term “messenger”, as defined in Rule 22.3 when used in Rule 54.10 , includes the bare neutral conductor whenever such conductor serves both as a conductor and also as a principal supporting member of the cable.

 

The term “unprotected conductors”, used in Rule 54.10 , means conductors as defined in Rule 20.9–E .

 

The vertical clearances from primary lead wires and drip loops to bare neutral multiconductor cable shall be maintained as specified in Rule 54.4–C6.

 

Note:    Revised October 9, 1996 by Resolution SU–40.

 

B.    Conductor Arrangement and Clearances

 

(1)    Clearance from Poles: Bare neutral multiconductor cables may have clearances less than 15 inches from centerline and 3 inches from surface of pole, as specified in Table 1, Column D, Cases 8 and 9 , respectively, but shall have a clearance of not less than 2.5 inches from the surface of pole and shall be supported on an insulator.

 

Note:    Revised January 8, 1980 by Decision No. 91186.

 

(2)    Clearance (Unattached) from Nonclimbable Street Lighting or Traffic Signal Poles or Standards: Multiconductor cables passing (unattached) nonclimbable street lighting and traffic signal poles or standards, including mastarms, brackets, and lighting fixtures may have a clearance less than 36 inches as specified in Table 1, Case 10, Column D , when the conductors are mechanically protected from abrasion by materials specified in Rule 22.8 . Such mechanical protection shall extend not less than 15 inches in each direction along the cable from centerline of pole, standard, attaching mastarm or fixture whether passing above, below or alongside. The conductors shall be installed in such a manner so as not to interfere with light distribution from lighting fixtures and shall not hamper workmen changing lamps or maintaining equipment.   

 

Note:    Added January 8, 1980 by Decision No. 91186 and revised March 9. 1988 by Resolution E–3076. Renumbered (old 54.10-B6) October 9, 1996 by Resolution SU–40

 

(3)    Clearance between Conductors in Bare Neutral Multiconductor Cables: No specified clearance is required between the insulated phase conductors and the bare neutral (see Rule 57.4–C ). The multiconductor cable shall be treated as a single conductor in the application of other clearance requirements.

 

(4)    Arrangement at Transitions from Bare Neutral Multiconductor Cable to Other Types of Construction (e.g., Extended Rack, Rack or Crossarm): The vertical clearance of 2 feet required by Rule 54.10–C4 , between a cable and other unprotected line conductors, shall not be held to apply at locations where multiconductor cable terminates (ends) and the cable transitions to other types of construction of the same voltage classification (0 - 750 volts). The following vertical clearance requirements shall apply:

 

a)    Where those other conductors are terminated (end) in another direction, no specified vertical clearance is required (see Figure 54–13 ).

 

b)    Where those other conductors are in tangent configuration (not terminated) and the type of construction is:

 

1)    Extended Rack Construction: The minimum vertical clearance above or below unprotected conductors shall be 8 inches and the multiconductor cable shall have a minimum clearance of 15 inches from the centerline of pole. The multiconductor cable may be either terminated directly on an extended rack neutral position insulator or on its own individual insulator.

 

2)    Rack Construction: The minimum vertical clearance above or below unprotected conductors shall be 10 inches. The multiconductor cable may be either terminated directly on a rack neutral position insulator or on its own individual insulator.

 

3)    Crossarm Construction: The minimum vertical clearance above or below unprotected conductors shall be 2 feet. The multiconductor cable may be terminated on the end of a crossarm and no specified vertical clearance is required (see Figure 54–18 ).

 

The climbing space shall be determined and maintained in the same quadrant or on the same side of the pole in accordance with climbing space requirements in Rules 54.7 , 54.9–F , 54.10–F or 54.12–F , whichever is related to the climbing space selected.
'

(5)    Arrangement for Deadend Construction: On poles with the messenger deadended in more than one direction, the grounded messenger or insulated phase conductors of the multiconductor cable shall not be attached to more than two sides of the pole and shall not be less than 2.5 inches from the surface of the pole. The climbing space shall be determined by Rule 54.10–F . (see Figure 54–17 ).

 

Note:    Added January 8, 1980 by Decision No. 91186 and revised March 9, 1988 by Resolution E–3076. Rule 54.10-B reformatted October 9, 1996 by Resolution SU–40.

 

C.    Vertical Clearance between Conductor Levels

When attached to poles, crossarms, or other supports at less than 15 inches from centerline of pole, bare neutral multiconductor cable shall be not less than 6 feet vertically above or 6 feet vertically below unprotected conductors, except as modified below:

 

(1)    With Guard Arm Placed above Cable: Where a guard arm is placed above bare neutral multiconductor cable in accordance with the provisions of Rule 57.7 , the vertical clearance of 6 feet may be reduced to not less than 4 feet below unprotected conductors of 750 - 22,500 volts.

 

(2)    Cable Attached 15 Inches or More from Center Line of Pole: When bare neutral multiconductor cable is attached (or supported) 15 inches or more from the center line of pole, the vertical clearance of 6 feet may be reduced to not less than 4 feet below unprotected conductors of 750 - 22,500 volts. When the vertical clearance is reduced to less than 6 feet, all portions of service drops attached at that level shall be 15 inches or more from the centerline of pole.

 

(3)    Cable Deadended under a Transformer: No guard arm will be required over bare neutral multiconductor cable deadended on the surface of a pole directly below a transformer installation. Such cable shall have a vertical clearance of not less than:

 

a)    4 Feet below unprotected line conductors; and

 

b)    As specified in Rule 54.4–C6 below, the lowest point of the drip loop of primary leads to the transformer(s); and

 

c)    10 Inches below the lowest part of the transformer case(s) or hangers(s).

 

(4)    Cable above and below Other Types of Construction of the Same 0 - 750 Voltage Classification: Where a bare neutral multiconductor cable is  supported on the same pole above or below another conductor level of the same voltage classification that is supported on:

a)    Crossarms or Extended Racks: The vertical clearance between these levels of conductors shall not be less than 2 feet and no guard arm is required (see Figures 54–14 through 54–17 ); or on

 

b)    Racks (Rule 54.9 ): The vertical clearance between these levels of conductors shall not be less than 10 inches for spans not exceeding 200 feet and 12 inches for spans in excess of 200 feet and no guard arm is required.

The climbing space shall be determined and maintained in the same quadrant or on the same side of pole through both conductor levels in accordance with climbing space requirements in Rules
54.7 , 54.10–F , or 54.12–F , whichever rule is related to the climbing space selected (see Figures 54–13 through 54–18 ).

 

EXCEPTION:    When rack construction is present, the more stringent climbing space requirements of Rule 54.9–F shall always be maintained through both levels.

This provision (
Rule 54.10–C4 ) is not applicable where the crossarm is a combination arm.

 

(5)    Multiple Related Bare Neutral Multiconductor Cables: Where multiple bare neutral multiconductor cables having the same secondary voltage source (related) are supported on the same pole, no specified clearance between such cables is required.

The climbing space shall be maintained in accordance with climbing space requirements in
Rule 54.10–F.

 

(6)    Multiple Unrelated Bare Neutral Multiconductor Cables: Where multiple bare neutral multiconductor cables not having the same secondary voltage source (unrelated) but are of the same voltage classification of 0 - 750 volts, and are supported on the same pole, no specified vertical clearance between such levels is required. However, each multiconductor cable shall be supported on a separate attachment (rack, spool, deadend clevis, etc.)

The climbing space shall be maintained in accordance with climbing space requirements in
Rule 54.10–F .

 

Note:    Formerly Rule 54.10-E. Renumbered and revised October 9, 1996 by Resolution SU–40.

 

D.    Service Drops

Phase conductors of all service drops taken from bare neutral multiconductor cables shall have insulation equivalent to that specified in
Rule 54.10–E1 .

Where service drops are supported on a multiconductor cable’s bare neutral messenger, the attachment to the messenger shall be an abrasion–resistant connection.

 

Note:    Revised October 9, 1996 by Resolution SU–40.

 

E.    Conductor Material and Strength

 

(1)    Insulation: The phase conductors and their jumper connections, excluding jumper connections at the pole, shall be covered with insulation suitable for the voltage involved and shall conform with the requirements of Rule 20.9–G.  Jumper connections at the pole shall comply with the clearance requirements of Table 2, Cases 17-D

 

Note:    Revised January 13, 2006 by Decision No. 05-01-030

 

(2)    Messenger: Where multiconductor cables are not maintained by workers using a cable chair, the additional allowance of the 200 pounds of vertical load specified in Rule 49.7–B may be reduced to 50 pounds to allow for the load imposed by workers on ladders.

 

F.    Climbing Space

 

(1)    Through Bare Neutral Multiconductor Cable Level: A climbing space shall be maintained through the level of conductors supported in bare neutral multiconductor cable construction. Said climbing space shall be maintained for a vertical distance of not less than 4 feet above and below such cable. The position of the climbing space through the levels of conductors in such cable construction shall be related to the climbing space for conductor levels above and below the cable in accordance with Rules 54.7–A and 93 .

Where multiconductor cable is installed at pole top, the climbing space shall extend up to the next level of such cable and need not be provided through and above such level.

 

(2)    Dimensions: The dimensions of the climbing space shall be 30 inches square, and shall be provided in one quadrant or on one side of the pole. The depth of the climbing space shall be measured from the centerline of the pole (see Figures 54–13 through 54–18 ).

 

(3)    Allowable Climbing Space Obstructions: Allowable climbing space obstructions are:

 

a)    Guys. However, not more than two guys having a vertical separation of 18 inches or less can be installed in any 4–foot section of climbing space.

 

b)    Suitably protected (covered only by wood, see Rule 22.8) :

 

1)    Vertical risers; or

 

2)    Vertical runs; or

 

3)    Ground wires.

 

Such risers, runs and grounds are allowable provided that not more than one is installed in any 4–foot section of climbing space.

 

c)    Insulators and their attaching brackets may extend one–half their diameter into the climbing space.

 

d)    Conductors may extend one–half their diameter into the climbing space.

 

e)    Street light brackets may extend one–half their diameter into climbing space. Associated street light bracket struts are allowed in climbing space.

 

f)    Operating rods (e.g., switch rods) and their associated hardware may extend one–half their diameter into climbing space.

 

g)    Bands, limited to 6 inches in width with no more than one band allowed in any 24–inch section of climbing space (these limitations are excluded for pole stubbing and pole splicing bands when pole step provisions are installed.)

 

h)    Bolts and their washers.

 

The terminals or terminal fittings of risers or runs shall not be installed within climbing space.

 

Note:    Revised March 9, 1988 by Resolution E–3076 and October 9, 1996 by Resolution SU–40.

 

G.    Sags

The sags of messengers which support multiconductor cable shall be such that under the maximum loading conditions, the tensions in the messengers shall not exceed the safe working stresses specified in
Rule 49.7–B . Where the multiconductor cables are not maintained by workers using a cable chair, the 200 pound additional allowance for vertical loading specified in Rule 49.7–B may be reduced to 50 pounds to allow for the load imposed by workers on ladders.   

 

H.    Fastenings

Hardware used in connection with messengers shall meet the strength requirement of
Rule 49.7–C . Deadend attachments used on messengers shall have a strength not less than that of the messenger. Where cables are not maintained by workers using a cable chair, the additional allowance of 200 pounds vertical load, specified in Rule 49.7–C may be reduced to 50 pounds to allow for the load imposed by workmen on ladders.

 

Note:    Revised October 9, 1996 by Resolution SU–40.

 

I.    Rule 54.10-I Deleted

 

Note:    Deleted October 9, 1996 by Resolution SU–40.

 

J.    Rule 54.10-J Deleted (See Rule 54.10-G )

 

Note:    Deleted October 9, 1996 by Resolution SU–40.

 

Note:    Rule 54.10 added January 2, 1962 by Resolution No. E–1109 and revised October 9, 1996 by Resolution SU–40.