in conventional lighting technology, the points where the wires for the filaments or electrodes pass through the envelope (wall) of the lamp, are subject to thermal stresses due to the heating and cooling of the lamp. Over time, this causes micro cracks which can allow atmospheric gases to enter the lamp contaminating the interior. In addition, the filaments or electrodes are heated by the passage of the electrical current causing them to evaporate over time. For example: the black rings often seen around the ends of fluorescent tubes are caused by the condensation of evaporated metals from the filaments. Induction lamps are completely sealed and have no filaments or electrodes penetrating the lamp walls. There is no possibility of thermal stress at the places where wires penetrate the light walls as there are no wires, and there are no filaments or electrodes inside the lamp to evaporate.