60W Lamp - Wrong Voltage

Two 60W lamps connected to 240V. One of them is not rated for that voltage.

The Video

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Electrical equipment is rated for a specific voltage. In this video, two 60W incandescent lamps are connected to a 240 volt supply. One lamp is rated for 240V, the other only 110V.

Although the voltage is approximately double, the power consumed will be 4x greater, so over 240 watts.

The 240V lamp is included for comparison, as it is very difficult to show actual brightness on camera.


Both lamps illuminate initially, although the 110V type is considerably brighter as would be expected.

After a few minutes, the 110V lamp has a noticeable darkening of the glass.

A few more minutes and the 110V lamp fails. The inside of the glass is now black, due to the tungsten filament evaporating and being deposited onto the glass envelope.
Higher power halogen filled lamps make use of this evaporation, however in those, the lamp is run at a much higher temperature so that the evaporated tungsten is redeposited onto the filament, rather than the glass.