Incandescent light bulb Small variations in resistivity along the filament cause "hot spots" to form at points of higher resistivity; a variation of diameter of only 1% will cause a 25% reduction in service life. These hot spots evaporate faster than the rest of the filament, which increases the resistance at that point—this creates a positive feedback that ends in the familiar tiny gap in an otherwise healthy-looking filament. Irving Langmuir found that an inert gas, instead of vacuum, would retard evaporation. General service incandescent light bulbs over about 25 watts in rating are now filled with a mixture of mostly argon and
Phase-out of incandescent light bulbs U.S. House passed the final 2012 budget legislation, which effectively delayed the implementation until October 2012. In 2014 the spending bill proposed by the House effectively blocked the energy efficiency standards in the Energy Independence and Security Act of 2007, which would have made incandescent light bulbs obsolete. As of 2018, incandescent bulbs are set to be banned in the United States in 2020. In February 2007, Australia enacted a law that will, in effect, by legislating efficiency standards, disallow most sales of incandescent light bulbs by 2010. The Australian Federal Government announced minimum energy performance standards (MEPS) for lighting