A stem and lamp capsule are connected together as an assembly using a retainer such that the stem is clamped to one end of the retainer and the capsule is clamped to the other end of the retainer. An oxidizable fuse is connected between leads of the capsule and electrical conductors of the stem. The retainer maintains the rigidity of the assembly and keeps a constant distance between the stem and the lamp capsule so that the repeatability and failure parameters of the fuse length can be maintained within acceptable tolerance.