Strictly speaking, dynamite is nitroglycerin-soaked charcoal, pressed into sticks. A dynamite package is a collection of a few sticks, taped together, and wired in parallel to a simple timer. This timer can be set for as little as ten seconds of delay, or up to a few minutes. Dynamite is especially helpful for clearing cave-ins, and can blow most doors apart.
Long-fuse dynamite is just like normal dynamite but, as the name suggests, has a longer fuse, which lasts for six seconds (twice as long as regular dynamite). Unlike powder charges, dynamite explodes when you shoot it, either off the hand of an enemy or on the ground when it is dropped. If you don't want to wait for six seconds, use V.A.T.S. to deliver the throw. Your target tends to wait patiently for the dynamite to explode.
A long-fuse dynamite can be found behind Jean Sky Diving wedged into the cliff.
3 long-fuse dynamite (sometimes just regular dynamite) can be found in an explosives box underneath a desk upstairs in the NCR CF Administration building of the NCR Correctional Facility
Numerous Powder Gangers will sometimes have long-fuse dynamite in their inventory.
Often found in explosive crates.
They are commonly sold from stores at random times.