Abstract: In a process for mounting a single-capped electric lamp (1) in a lampholder (20) of a luminaire (22), use is made of a cap (3) having an end zone (9) in its shell (4) which in a mounted lamp is outside the lampholder. The end zone (9) is provided with relief (15) enabling a mounting tool (30) to seize the cap (3) with little force and nevertheless to have a firm grip onto the lamp. The position of the relief (15) may be related to the position of coupling device (10) present at the cap (3) for cooperation with the lampholder, enabling the tool (30) to approach the holder (20) with the cap (3) in a predetermined position. By the process it is counteracted that a lamp (1) having a cap (3) which is suited to be used in the process and a luminaire (22) having the holder (20), becomes damaged during assembling.