General Order 64

General Clearance Requirements – All Classes Of Lines

43    Minimum Clearance Of Wires From Other Wires.

By clearance between wires crossing other wires (see first section of Table 2) is meant situations in which wires carried on different pole line supports cross each other.  It is not intended to cover the incidental crossing of wires carried on the same pole line.

The clear space between any overhead line conductor or wire and any other conductor or wire over which the former crosses; and the vertical separation between wires on one pole line and those wires on a collinear pole line; and the horizontal separation between wires of the same voltage class on the same crossarm; and the vertical separation between wires on different linearms of the same pole; and the clearances of line wires from vertical or lateral conductors or guy wires on the same pole line or on conflicting pole lines shall not be less than the values given in Table 2 under the most severe conditions of temperature and loading that apply, as well as side swing due to wind.

Where conductors are supported by suspension or disc type insulators and not dead ended at the pole or structure or otherwise prevented from swinging, the side swing mentioned above shall be figured on the assumption that the maximum deflection of the supporting insulators is 45 degrees from the vertical.

Where the upper line at a crossing between two lines is supported by suspension insulators, the clearances above lines crossed shall be increased sufficiently above those given in Table 2 to prevent the clearance from being reduced by the breaking of a conductor in either adjoining span by more than 25 per cent below the value given in Table 2.  An arrangement of insulators preventing displacement toward the crossing will avoid the necessity of any increase over the clearances give.