General Order 95
Definitions of Terms as Used in The Rules of This Order
20.6     Circuit means a conductor or system of conductors located outside of buildings and through which an electric current flows or light is transmitted.
Note:     Revised November 21, 1990 by Resolution SU–6.
A.     Class C Communication Public and Private
Circuits mean circuits used for public or private communication service
and are divided as follows:
Current carrying circuits operating at potentials not exceeding 400 volts
to ground or 750 volts between any two points of the circuit and the transmitted
power of which does not exceed 150 watts. When operated at less than 150 volts,
no limit is placed on the capacity of the system. Any circuit which exceeds
the above values used for information transport shall be treated as a supply
circuit and must meet the supply requirements for the voltage involved.
(2)     Fiber optic circuits transmitting
light for communication purposes (see definition,
Note:     Information systems including,
but not limited to, telephone, railroad–signal, data, clock, fire or police
alarms, cable television and other systems conforming with the above are included
in this classification.
Note:     Revised January 19, 1994
by Resolution SU–25 and September 7, 1995 by Resolution SU–35.
B.     Intentionally Left Blank.
Note:     Rule deleted January
19, 1994 by Resolution SU–25.
Railway Signal Circuits mean those supply and communication circuits
used primarily for supplying energy for controlling the operation of railway
block signals, highway crossing signals, interlocking apparatus and their
Circuits which operate at less than 400 volts to ground are considered as
communication (Class C) circuits and shall be so classified and treated provided
that, if the voltage exceeds 150 volts between conductors the power transmitted
shall not exceed 150 watts. Where all circuits of a line are owned and operated
by one utility, the voltage between conductors carrying in excess of 150
watts may be increased to not more than 250 volts and the signal circuits
may be considered as communication (Class C) circuits.
All railway signal circuits which do not meet the requirements above shall
be treated as supply circuits of corresponding voltage.
Supply Circuits mean those circuits which are used for transmitting
a supply of electrical energy.
(1)         Class E circuits include constant potential alternating or direct current
circuits of 300,000 volts or more between any two conductors.
Class H circuits include the following:
Constant potential alternating current circuits of 5,000 volts or more but less than 300,000 volts between any two conductors.
Constant potential alternating current circuits of 2,900 volts or more but less than 174,000 volts between any conductor and ground.
Constant potential direct current circuits exceeding 750 volts but less than 150,000 volts between any conductor and ground.
Constant current circuits of 7.5 amperes or less supplied from transformers or devices having a normal full–load output voltage of 5,000 volts or more.
Constant current circuits of more than 7.5 amperes supplied from transformers or devices having an open–circuit voltage of 2,900 volts or more.
Class L circuits include the following:
Constant potential alternating or direct current supply circuits of lower voltage than Class H.
Constant current circuits of 7.5 amperes or less supplied from transformers or devices having a normal full–load output
voltage less than 5,000 volts.
Constant current circuits of more than 7.5 amperes supplied from transformers or devices having an open–circuit output voltage less than 2,900 volts.
Note:     Revised March 30, 1968 by Decision No. 73813.
Class T Circuits mean trolley contact conductors, feeder wires and
other conductors metallically connected to such contact conductors, used in
electric railway or trolley operation. These Class T circuits are supply circuits,
further classified as Class L or Class H depending upon the voltage and nature
of current used (See Rule 20.6–D