Minecraft wiki entry for Redstone_mechanics, associated text: An opaque block (e.g., stone, sandstone, dirt or grass, etc.) powered by a power component, or by a repeater or comparator, or placed above active redstone torch, is said to be 'strongly powered' or 'hard-powered' (a different concept from power level). A strongly powered block can power adjacent Redstone dust (including dust on top of the block or dust beneath it).