There are several problems with this installation already that need to be changed to met NEC, I would say, remove the square box and start fresh. [Make sure the power is off at the breaker before you start] Back in the day when I was in the trade, I had a 3 1/2" dia deep cut hole saw, Electrical supply companies make an "Old Work" ceiling box that will pop right into the hole sawn by the 3 1/2" hole saw with several different anchoring options available. The main thing is to get it securely mounted and the Romex correctly routed and clamped to the new (old work) outlet box. Having the box flush to the finished ceiling level makes fixture installation so much easier and more professional-looking. If you are uncomfortable with this a good Electrician could do this in less than one hour, the cost of a service call and a couple bucks for the box. Good Luck. Dave Mentor, Ohio

There are several problems with this installation already that need to be changed to met NEC, I would say, remove the square box and start fresh. [Make sure the power is off at the breaker before you start] Back in the day when I was in the trade, I had a 3 1/2" dia deep cut hole saw, Electrical supply companies make an "Old Work" ceiling box that will pop right into the hole sawn by the 3 1/2" hole saw with several different anchoring options available. The main thing is to get it securely mounted and the Romex correctly routed and clamped to the new (old work) outlet box. Having the box flush to the finished ceiling level makes fixture installation so much easier and more professional-looking. If you are uncomfortable with this a good Electrician could do this in less than one hour, the cost of a service call and a couple bucks for the box. Good Luck.