Talk:Command Center/@comment-87.172.194.202-20121226043938/@comment-71.79.132.51-20130202043821

It referred to the bars at the top of the screen. If the defender's "health" (the sum of all the health from buildings and defending units) falls below 50%, a bubble appears. If that overall bar turns red (less than 25% of the defender's health left) then the maximum bubble time is given. Turret platforms that are maxed tend to make up such a large portion that their destructions almost always can bubble a player.