troubleshooting device which comprises, in an electric incandescent bulb has, at least two filaments, of a same power, one can replace the other in the event of rupture

摘要

The incandescent lamp bulb has at least two filaments of the same power (1,2), one of which replaces the other in case of breakage. The bulb has an envelope (14) positioned in a lower metal case (12) with connection pins extending outwardly and connected to the filaments. The bulb can be mounted in a holder which allows lighting of one or both filaments.