A lighting system with an isolating power supply must operate at _____ volts peak to be considered low voltage.

To consider a lighting system with an isolating power supply as low voltage, it must operate at a maximum of 30 volts peak. This threshold is established by industry standards to differentiate low voltage systems from higher voltage applications, which can pose more significant safety risks. Keeping the operational voltage at or below 30 volts allows for safer installations, reducing the risk of electric shock and ensuring compliance with safety regulations.

In the context of low voltage communication systems, adhering to this voltage limit is essential for proper system design and compatibility with low voltage equipment. Systems operating at this level are more manageable in terms of installation, maintenance, and regulatory compliance, making the use of 30 volts peak the correct answer for classifying a lighting system as low voltage.