Unsurpassed circuit protection and application flexibility.

Industry leading offer since 1955 with features engineered for faster installation, reliability and quality. Contractors installing QO know it’s the World’s Finest!

Square D™ QO Load Centers

The QO load center and circuit breaker family is designed to satisfy individual requirements with a comprehensive selection:

  • Single and three phase
  • 3/4" circuit breaker width
  • 30 to 400 amps 2 to 42 circuits
  • Indoor and outdoor versions
  • Separate flush or surface mount covers
  • Full complement of accessories



  • Backed Out Neutral Screws save labor and installation time.
  • Exclusive shielded copper bus features electro tin-plated copper bus bars sandwiched between two rugged polymer shields to insulate and secure the interior.
  • Straight-in mains wiring and uniform termination lugs help minimize service cable bends, cutting waste and saving installation time.
  • Convertible mains allow fast field conversion between main breaker and main lugs to meet changing job requirements.
  • Standard 22,000/10,000 ampere series short circuit current rating on main breaker load centers provides increased application capability.
  • QO three-phase main circuit breaker panels can be field upgraded to provide 100,000A short circuit current ratings.
  • Single, captive interior mounting screw can't be lost. Interior mounts quickly and can easily be removed during rough-in for paint or theft protection.
  • Split branch neutral with up to 50% more terminations than UL requirement -- simplifies wiring and reduces clutter.
  • Indoor enclosures designed to rotate 180 degrees to accommodate top or bottom service entrance feed, saving expensive service cable.
  • Combination slot/square-drive neutral, ground, and cover screw accommodate both standard flat blade screwdrivers and square-head drivers. Three ground bar mounting locations (left, right, and end) make it easier to wire.


  • Residential
  • Remodels/Upgrades
  • Commercial
  • Industrial
  • Agricultural