Abstract: A lamp has a tungsten filament within an evacuated glass bulb and connected to electrical conductors. Connected between the two electrical conductors are a series-connected neon and resistor. In use, the tungsten filament provides a primary light-emitting device, and the neon provides a secondary light-emitting device. The light intensity emitted by the filament is very much greater than that emitted by the neon. Therefore, in normal use, the neon will hardly be seen. However, in the event that the filament fails, the neon continues to emit light. With the main filament extinguished, the light emitted by the neon becomes quite visible, and serves to indicate the presence of electric power at the lamp contacts. Therefore, a user can switch off the power supply to the lamp at the local switch, the neon indicating when this has safely been done.