In this paper, a new ballistic limit equation (BLE) for satellite equipment placed behind satellite structure walls is presented. Application of this equation in micrometeoroid and space debris (MM/SD) risk analysis (RA) tools for satellites can lead to a more realistic quantitative assessment of the actual failure risk of satellite equipment from hypervelocity impacts (HVI) and hence, of the failure risk of a satellite. This is because in contrast to the BLEs that are currently in use in RA tools, in the new equation the intrinsic shielding capabilities of the satellite equipment are considered explicitly.The BLE has been developed for application to configurations consisting of a Whipple shield or a honeycomb sandwich panel placed in front of a backwall. It considers explicitly the thickness, material and spacing of each of the three involved plates. The backwall represents the cover plate or the external wall of spacecraft equipment that is placed behind the spacecraft's structure wall. The BLE has been experimentally calibrated to the most common spacecraft equipment: fuel and heat pipes, pressure vessels, electronics boxes, harness, and batteries. Further, suitable failure criteria have been defined for each equipment type. The critical projectile masses calculated with the new BLE for satellite equipment placed behind satellite structure walls are considerably larger than the critical projectile masses calculated for the standalone structure wall of the satellite.