What is the guideline for cable runs longer than 25 feet?

• A. Cable runs longer than 25 feet have no effect on resistance.
• B. They may increase electrical resistance beyond rated capacity; keep cable runs to a minimum length or use proper cable.
• C. Use wireless alternatives whenever possible.
• D. Always use the longest possible runs to reduce voltage drop.

Answer: (B)

Long cable runs increase resistance, which in turn can cause a noticeable voltage drop and extra heating for the conductor. That means devices at the far end may not get the voltage they need to operate reliably, and wiring can overheat if the current is too high for the chosen cable. The safest guideline is to keep runs to a minimum or choose a cable with a lower resistance per unit length (a larger gauge or a cable type rated for the load and distance). If a longer run is unavoidable, calculate the expected voltage drop and select proper cable sizing or installation methods to keep the voltage within tolerance. Using wireless options can be a supplementary approach when feasible, but it doesn’t address the resistance issue in a physical cable run. The core idea is that length directly affects resistance and performance, so longer than 25 feet should be evaluated with the correct cable sizing or alternatives to maintain safety and function.