General Order 64

General Clearance Requirements – All Classes Of Lines

41    General Provisions And Relative Levels Of Wires.

(a)    These clearances shall apply to all wires, both signal and supply, crossing over streets, highways, railway tracks, roadways, etc., as well as crossings of wires with other wires and clearances between wires under the various conditions as may be met.

(b)    Where two or more utilities maintain poles, structures or wires concerned in the clearance, that utility which last, in point of time, shall place the pole, structure or wire concerned in the clearance must establish and maintain the clearance required in these rules, between its poles or wires and the poles or wires and the poles or wires of the other utility.

(c)    Where supply and signal lines, or supply lines of different voltage classifications are in co-linear construction (see Definition 17(m)), or on the same poles or towers, or at crossings of wires with other wires, the higher voltage lines shall, if conditions permit, be carried at the higher levels.  This can not always be done, particularly where Class “T” circuits are involved or where pole lines are jointly occupied.  Trolley contact conductors will, or course, always cross below all other wires, and trolley feeders will usually do likewise, since for practical purpose they are generally run in approximately the same horizontal plane as the trolley contact wires.

(d)    In such exceptional cases where the standard arrangement as to relative levels of conductors at crossings, co-linear construction, or joint poles, specified in (c) above, can not be maintained, then the line or conductors occupying the upper position shall be subject to the same requirements, in so far as mechanical strength is concerned, as would normally apply to the upper line if the specified arrangement of levels were adhered to, except that where none of the conductors involved in the departure from arrangement carry a potential exceeding 750 volts this requirement may, be omitted.  Where trolley contact conductors of voltage above 750 volts are crossed by supply or signal lines of less voltage, the latter shall conform as regards mechanical strength to the requirements for ordinary supply lines of voltage equal to that of the trolley contact conductor.

(e)    Light and power service shall not and signal service drops should not cross in a span above supply lines (except Class “T” lines) of 750 to 5000 volts and neither class of service drops shall cross in a span above supply lines over 5000 volts.

(f)    Supply lines below 750 volts should not be above supply lines of over 7500 volts.

(g)    Supply lines of 750 to 17,000 volts should not be above supply lines of over 17,000 volts.

(h)    Supply lines not exceeding 300 volts to ground and all Class “T” lines may cross under telephone, telegraph or signal lines, provided the clearances in Tables 1 and 2 are observed.

(i)    Where signal lines not for public use and supply lines below 7500 volts are owned by the same utility they may be placed on the same crossarm when necessary.  Where such supply line is above 750 volts the signal line shall be supported on the opposite end of the arm from the supply line, a 36-inch horizontal clearance being maintained between the signal line and nearest supply line.  (See Appendix E, Fig. 38.)