Minecraft wiki entry for Redstone_Torch, associated text: A redstone torch experiences "burn-out" when it is forced to change state (by powering and de-powering the block it is attached to) more than eight times in 60 game ticks (three seconds, barring lag). After burning out, a redstone torch produces a "smoke" particle and a hiss similar to an extinguished fire, deactivates, and then ignores attempts to change its state until the number of state changes in the last 60 game ticks drops to fewer than eight—after that it re-activates when it receives a block update (an adjacent block changing its state) or a redstone update that would not normally deactivate the redstone torch. There is no limit on how often a single redstone torch can burn out.