Editing Fluorescent lamp (section)

====Instant start====
[[File:T12 Fluorescent lamp electrodes - rapid start and instant strt.jpg|thumb|T12 fluorescent tubes. The first two are rapid start, (for "tombstone" and socket holders respectively) while the third is an instant-start lamp. The instant-start  has a characteristic, rounded, single pin, for plugging into the spring-loaded socket holders.]]
''Instant start'' fluorescent tubes were invented in 1944. Instant start simply uses a high enough voltage to break down the gas column and thereby start arc conduction. Once the high-voltage spark "strikes" the arc, the current is boosted until a [[glow discharge]] forms. As the lamp warms and pressure increases, the current continues to rise and both resistance and voltage falls, until mains or line-voltage takes over and the discharge becomes an arc. These tubes have no filaments and can be identified by a single pin at each end of the tube (for common lamps; compact cold-cathode lamps may also have a single pin, but operate from a transformer rather than a ballast). The lamp holders have a "disconnect" socket at the low-voltage end which disconnects the ballast when the tube is removed, to prevent [[electric shock]]. Instant-start lamps are slightly more energy efficient than rapid start, because they do not constantly send a heating current to the cathodes during operation, but the cold cathodes starting increases sputter, and they take much longer to transition from a glow discharge to an arc during warm up, thus the lifespan is typically about half of those seen in comparable rapid-start lamps.<ref>''Mechanical and Electrical Equipment for Buildings'' by Walter T Grondzik, Alison Kwok, Benjamin Stein, John S Reynolds, Wiley Publishing, 2010, pp. 545–546</ref>