6.3.2.2 UL Mechanical Strength Test, Variable (UL 60950-1, 2nd edition, Section 4.2.11.1) The slide/rail mounted equipment shall be installed in a rack in accordance with the manufacturer’s instructions. With the slide/rail mounted equipment in its extended position, a force in addition to the weight of the equipment shall be applied downwards through the center of gravity for 1 min to account for user or service personnel stacking on top of installed rack mounted equipment in the extended position, during equipment installation. The additional force shall be applied downwards through the center of gravity by means of a suitable test tool providing contact over a circular plane surface 30 mm in diameter. For slide-rail mounted equipment, where the slide rails are mounted horizontally on each side of the equipment, the total force applied to the slide rails shall be equal to the greater of the following two values: 150% of the equipment mass plus 330N (74.2 lb.). 150% of the equipment mass, plus an additional mass, where the additional mass is equal to the equipment mass up to a limit of 530N (119.1 lb.). TABLE 29: TEST WEIGHT PER SLIDE SET