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Wire Size GuideNEC 2023 · 2026 · Updated May 2026
What wire size for a 800 amp circuit?
800A circuits typically require parallel conductors or large kcmil wire sets. WireRef does not size parallel conductor assemblies on this page. Consult a licensed electrician or electrical engineer for conductor sizing, raceway fill, and termination details. Common applications: 800A commercial and industrial main services.
CopperParallel
AluminumParallel
Breaker800A
Voltage480V
Parallel conductors required
An 800 amp service is used for medium to large commercial buildings and industrial facilities. This level requires parallel conductor sets or bus duct, CT-rated metering, and typically a separate utility transformer.
800A is a standard breaker/fuse size per NEC 240.6(A). At this level, bus duct is often more practical than individual conductors. Four sets of 250 kcmil copper or 350 kcmil aluminum per phase are typical. Working space clearances per 110.26 are critical.
800A exceeds WireRef's single-conductor sizing range. Circuits at this rating typically use parallel conductors, large kcmil conductors, or installation-specific equipment that cannot be reduced to a single wire-size answer.
Use a licensed electrician or electrical engineer to size the conductor sets, raceways, lugs, and overcurrent protection for your installation. At this amperage, the service type, conductor material, termination rating, and installation method all materially affect the answer.
WireRef's single-conductor wire-size guidance currently tops out at 225A. For higher ratings, refer to engineered drawings, manufacturer data, and your local code requirements instead of a simplified breaker-to-wire chart.
Requirements vary by state. NEC edition, licensing, permits, and GFCI rules differ by jurisdiction. Check your state or pick it below for personalized info across WireRef.
Important: For reference only. Not a substitute for a licensed electrician. Electrical work can cause serious injury, death, fire, or property damage if performed incorrectly. Always hire a licensed electrician for electrical work, especially for service upgrades, panel work, and 240V circuits. Values are derived from NFPA 70 (NEC) for educational purposes. Always verify against your locally adopted NEC edition and amendments - local jurisdictions may enforce stricter requirements. WireRef provides reference information only and is not responsible for work performed based on this content. NEC® is a registered trademark of the National Fire Protection Association. Free NEC access via NFPA · OSHA Electrical Safety · Terms of use.