Hey there, the electric ball, also called spherical lighting is randomly floating around the underground tunnels.
Best strategy is to pick up a key from room on the left side near underground entrance, then go down the main corridor and turn right after you pass 3 locked doors, use the key to open doors to storage room and take pistol, smg and pistol ammo from the ground.
Now instead of trying to get around the anomaly, try to defeat monsters with weapons you just got. After you are done you need to carefully observe where the anomaly is flying, it's movements are random so it's best to advance when it gets far away and you stop hearing the buzzing sound. You need to run around a long horizontal wall at the end of main corridor and find a second tunnel which will lead you to dead end with locked doors and key to pick up. You will need to use that key to open doors downstairs on the opposite site, also when you find the key you need to run away as fast as you can and if the anomaly gets close - try to lose it with circular movement around the tunnels, you will eventually find a way downstaris which will require the last key you picked up previously. I hope that helps, let me know if you keep having problems with that section and I will find a way to blance it a bit better