Can QO or Homeline load centers be mounted sideways?
Horizontal mounting of load center
QO and Homeline
No. Load centers cannot be mounted sideways. When mounted horizontally, half of the breakers in the load center would have their handles pointing down when in the ON position, which would be a violation of the 2002 National Electrical Code, Article 404.7. Breaker handles are allowed to be up when in the ON position, or sideways in either direction, but never down.