The Physics of Loss
In electrical engineering, "Voltage Drop" is the reduction in electrical potential as current travels through a conductor. Every foot of wire has resistance, and that resistance turns your expensive electricity into useless heat.
Why 3% is the Magic Number
The National Electrical Code (NEC) recommends a maximum voltage drop of 3% for branch circuits. Why? Because if the voltage drops too low, motors run hotter, lights dim, and sensitive electronics can fail or behave unpredictably.
Calculating the Drop
The drop is determined by: Current (A) * Distance (ft) * Resistance (Ω/ft). To reduce the drop, you must either reduce the distance or decrease the resistance by using a thicker (lower gauge) wire.
Long-Distance Design
For long runs (e.g., powering a shed 200 feet from the main house), you almost always have to "up-size" the wire beyond what the circuit breaker requires. A 20-amp circuit might need #12 wire for a short run, but #8 wire for a long one.
Conclusion
Don't let your power vanish into thin air. Use our Voltage Drop calculator to ensure your electrical designs are efficient, safe, and up to code.