Service Entrance Calculator
Calculate service entrance conductor voltage drop, load voltage, and practical conductor sizes for feeder and service planning.
Estimate voltage drop on customer-owned service conductors before a meter-main, CT cabinet, or service switchboard location is locked in. This planning check does not replace utility coordination, available-fault-current review, or final NEC service-equipment design.
Service Inputs
current, voltage, route length, and conductor choice
200A meter-main, 160A load, 150 ft
4/0 Al lands near 4.80V of drop, about 2.0% at 240V. Moving to 250 kcmil Al cuts that to about 4.07V, about 1.7%.
320A service section, 260A load, 210 ft
350 kcmil Al lands near 6.60V, about 2.75% at 240V. 500 kcmil Al drops near 4.63V, about 1.93%.
208Y/120V three-phase, 300A, 180 ft
Two parallel 3/0 Cu sets land near 3.58V, about 1.72% at 208V. That is often easier to live with than a single larger set in a crowded route.
Related Tools
Transformer Secondary Calculator
Check customer-side transformer secondary runs before the service section lands at a remote switchboard or panelboard.
Maximum Circuit Length Calculator
Move from a fixed service conductor size to the longest practical run that still stays inside your drop target.
Calculadora de Secção de Cabo
Run the full conductor-selection workflow once the service route and current are confirmed.