Given: A centralized sound distribution system is being installed in a single story church building. The amplifier output circuit carries and audio-program signal of 25 volts. The open, circuit voltage is 50 volts. Under these conditions, which of these wiring types is permitted?

Given: A centralized sound distribution system is being installed in a single story church building. The amplifier output circuit carries and audio-program signal of 25 volts. The open, circuit voltage is 50 volts. Under these conditions, which of these wiring types is permitted?