Section 305

Section 305.TABLE A Vertical Separation of Crossarms Carrying Conductors

1. BASIC SEPARATION.

The separations given in the following table are for crossarms carrying conductors of 0 to 50,000 volts attached to fixed supports.

2. INCREASED SEPARATION FOR VOLTAGES EXCEEDING 50,000 VOLTS.

For voltages greater than 50,000 volts the clearances in the table below shall be increased at the rate of 0.4 inch per 1,000 volts of the excess.

				Supply conductors: preferably at higher levels ⁶
				Open wires, 0 to 750 volts; cables, having effectively grounded continuous metal sheath, or insulated conductors supported on and cabled together with an effectively grounded messenger, all voltages						15,000 to 50,000 volts



		Conductors usually at lower levels				750 to		8,700 to
						8,700		15,000
						volts		volts		Same		Different
										utility		utilities



Communication conductors:				Feet		Feet		Feet		Feet		Feet
		General		^{1, 2}	4		4		6				6
		Use in operation of supply
			lines		2	³	2		4		4		6
Supply conductors:
		0 to 750 volts			2	⁴	2		4		4		6
		750 volts to 8,700 volts				⁴	2		4		4		6
		8,700 volts to 15,000 volts:
		If worked on alive with long-handled tools and adjacent circuits are neither killed nor covered with shields or protectors
									4		4			6
		If not worked on alive except when adjacent circuits (either above or below) are killed or covered by shields or protectors, or by the use of long-handled tools not requiring linemen to go
		between live wires							2	⁵	4	⁵		4
	Exceeding 15,000 volts, but
		not exceeding 50,000 volts								⁵	4	⁵		4

¹Where supply circuits of 550 volts or less, with transmitted, power of 3,200 watts or less, are run below communication circuits in accordance with Rule 220B2 the clearance may be reduced to 2 feet.

²In localities where the practice has been established or placing on jointly used poles, crossarms carrying supply circuits of less than 300 volts to ground and crossarms carrying communication circuits at a vertical separation less than specific in the table, such existing construction may be continued until the said poles are replaced provided that –

The minimum separation between existing crossarms is not less than 2 feet, and that –

Extensions to the existing construction shall conform to the clearance requirements specified in table 11.

When communication conductors are all in cable, a supply crossarm carrying only wires of not more than 300 volts to ground may be placed at not less than 2 feet above the point of attachment of the cable to the pole provided that –

The nearest supply wire on such crossarm shall be at least 30 inches horizontally from the center of the pole, and that –

The cable be placed so as not otherwise to obstruct the climbing space.

³This shall be increased to 4 feet when the communication conductors are carried above supply conductors unless the communication-line-conductor size is that required for grade C supply lines.

⁴Where conductors are operated by different utilities, a minimum vertical spacing of 4 feet is recommended.

⁵These values do not apply to adjacent crossarms carrying phases of the same circuit or circuits.

⁶A conductor which is effectively grounded throughout its length, and is associated with a supply circuit of 0 to 22,000 volts may have the clearance specified for cables having effectively grounded continuous metal sheath or messenger.