ESA Certified Alarm Technician Practice Exam

How should wires be run to minimize interference from AC power lines?

1. In close proximity

2. Parallel

3. Perpendicular

4. In twisted pairs

The correct answer is: Perpendicular

Wires should be run in a perpendicular orientation to minimize interference from AC power lines. When wires are run perpendicular to AC lines, the electromagnetic fields generated by the AC lines have less opportunity to induce unwanted voltages or currents in the signal wires. This orientation effectively reduces the likelihood of interference, maintaining the integrity of the signals being transmitted through the wires. In contrast, running wires in parallel with AC power lines can lead to increased interference, as any electromagnetic fields generated by the AC lines can more readily couple with the signal wires. Additionally, running wires in close proximity to AC lines does not provide sufficient separation to mitigate interference, which can degrade signal quality. Although twisted pairs are an effective method to reduce interference, especially for data transmission, the critical factor in this context is the orientation relative to AC power lines. Therefore, running wires perpendicular is the best practice for minimizing interference.