When installing a ceiling lamp or retrofitting a new accessory, you take into account the weight of the unit. Require heavy accessories outlet box for flush mount ceiling light directly to a ceiling joist. Also check local codes to verify that seamless connections are allowed and, if so, use thread on cable connectors.
For flush mount ceiling light, turn off power to the circuit at the fuse box or circuit breaker. Take the glass globe or shade of the existing lamp and remove the bulb. Loosen the cap nut in the center of the apparatus. Remove the screws of adjacent mounting accessory and gently pull the unit away from the box and the output ceiling, exposing the wires.
Disconnect the black (hot) wire first. Thread a Wire nut at the end of the black cable connector and then get the power back up in the outlet box. Flush mount ceiling light with Disconnect the cable (neutral) white. Thread a cable connector on the end of white wire then put the wire back up in the outlet box.