Minecraft wiki entry for Tripwire_Hook, associated text: To place tripwire, use the Place Block control with a string. Tripwire in a valid tripwire circuit has a short hitbox (0.09375 or 3/32 blocks high, with the bottom 0.0625 or 1/16 blocks above the block below), while tripwire not in a valid tripwire circuit has a taller hitbox (0.5 blocks high, bottom not raised).