QO Load Centers offer premium features like QO breakers, ground arc fault interrupters and surge arresters. QO load centers are designed for residential and industrial use to protect electrical systems, equipment and people. Systems are single or three phase and have indoor and outdoor versions. Indoor enclosures are designed to be rotated 180 degrees to accommodate top or bottom service entrance feed. Indoor enclosures are designed to be rotated 180 degrees to accommodate top or bottom service entrance feed. This handle padlock attachment is for padlocking 50A to 125A main circuit breaker in a convertible load center in the OFF position. This accessory is meant for the OFF position and convertible load centers.