Wire Sizing for 200 Amp Residential Service
Selecting the correct wire size for your electrical service is critical for safety, code compliance, and system performance. An undersized wire creates heat buildup that damages insulation and creates fire hazards. Here is what you need to know about wire sizing for 200-amp service.
Standard Wire Sizes
Per NEC Table 310.16, the standard conductor sizes for a 200-amp service are 2/0 AWG (also written as “2 ought”) for copper conductors and 4/0 AWG for aluminum conductors. These sizes apply to THWN, THHN, and XHHW insulation types at standard temperature ratings. The neutral conductor may be sized smaller (typically 1/0 copper or 2/0 aluminum) if the load calculation supports it, but many jurisdictions require a full-size neutral.
Copper vs. Aluminum
Copper offers superior conductivity and smaller physical size for the same amperage. However, copper is significantly more expensive than aluminum. For service entrance cable, aluminum is the standard choice for most residential installations due to the cost savings, with proper anti-oxidant compound applied at all connections to prevent corrosion. Copper is preferred for branch circuit wiring within the home.
Distance Considerations
If the run from the meter to the main panel is longer than approximately 100 feet, voltage drop becomes a factor. For longer runs, you may need to increase the wire size by one or two gauges to maintain voltage within acceptable limits (typically 3% maximum drop). A voltage drop calculation based on your specific distance and load will determine if upsizing is necessary.
Conduit Fill
When running individual conductors through conduit, NEC Chapter 9 tables govern the maximum fill percentage. Oversized conduit may be needed for 4/0 aluminum conductors in certain configurations. Your electrician will calculate the correct conduit size during the project planning phase.
IB Lighting carries a full inventory of service entrance cable, individual conductors, and conduit in the sizes needed for 200-amp residential service. Call (800) 674-9019 for pricing and availability.