Final answer:
Voltages over 700 kV are classified as experimental because this is above the standard range for long-distance transmission, which is usually between 120 kV and 700 kV.
Step-by-step explanation:
Voltages over 700 kV are considered to be experimental voltages. This classification is based on standard practices of electricity transmission where electric power is typically generated at voltages greater than 10 kV and transmitted over long distances at voltages ranging from 120 kV to 700 kV to limit energy losses. Voltages such as 14.2 kV, and even much higher feasible voltages like 400 kV, are within the norm for power distribution systems, but when voltages extend into the millions of volts, such as 335 MV mentioned in a challenge problem, they exceed practical application limits and are deemed extraordinarily high, which could suggest that the value is in the experimental range or is an erroneous result.