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Wire Size GuideNEC 2023 · 2026 · Updated May 2026
What wire size for a 1200 amp circuit?
1200A 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: 1200A commercial and industrial main switchgear.
CopperParallel
AluminumParallel
Breaker1200A
Voltage480V
Parallel conductors required
A 1200 amp service is standard for large commercial buildings, data centers, and industrial facilities. Bus duct is the primary distribution method. Individual conductors would require six or more parallel sets per phase.
1200A is a standard breaker/fuse size. At this amperage, bus duct (busway) is standard practice. NEC 368 covers busway requirements. Working space per 110.26 requires 4 feet of clearance for 601V-1000V or 3.5 feet for 480V systems. Arc-flash labeling per NFPA 70E is essential.
1200A 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.