Final answer:
The question about the maximum allowable percentage of wireway fill for signal and control conductors is an electrical code specification, not directly related to the power loss examples provided. For accurate information, consult the relevant electrical code.
Step-by-step explanation:
The student's question pertains to the maximum allowable percentage of the cross-sectional area of a wireway that can be used for signal and/or control conductors. This is a detail that is typically specified in electrical codes or standards, which can vary depending on the region and specific application the wireway is designed for.
For power distribution, using high voltages is more economical because it reduces the current needed and thus the power loss in transmission lines. This concept is sometimes explained with examples, like the one in your question mentioning that transmitting 100 MW of power at a low voltage such as 25 kV would require a current of 4000 A, leading to a significant 16.0% power loss. In contrast, higher voltage systems will incur substantially lower power losses.
The amount of conductor fill within a wireway for signal or control conductors is not directly related to the power loss principles discussed. Since the provided information does not explicitly state the maximum allowable percentage for conductor fill, it is essential to refer to the relevant electrical codes such as the National Electrical Code (NEC) in the United States for the precise limitations.