Explosives

Explosives is a Fallout 3 and Fallout: New Vegas skill, replacing the Traps and Throwing skills from previous games. Its governing primary statistic is Perception.

Uses
The Explosives skill governs all mines and grenades. The higher your skill, the higher the damage you inflict. A minimum skill level is also required to unlock the Demolition Expert perk.

This skill does not apply to Missiles or Mini Nukes; use Big Guns instead. Explosives also does not apply to the act of pants-exploding—use Sneak to successfully plant a nasty surprise.

Use Explosives to set Frag Mines, Pulse Mines, Plasma Mines, or Bottlecap Mines. They all explode by proximity, not by contact. Mines may be placed anywhere, including tables and ledges to bring the area of effect closer to the head or torso. You may also reverse-pickpocket mines into an NPCs inventory.

In Fallout 3 the Explosives skills affects the distance and accuracy of a thrown bomb: including the Frag Grenade, Pulse Grenade, Plasma Grenade and Nuka Grenade. Grenades may also be used to rearm a formerly rigged Terminal. While using V.A.T.S., grenades explode on contact with a target. Don't forget that you can hold down the attack button to charge the throw of a grenade.

Hostile mines and grenade traps may also be disarmed. Read below for the required skill to disarm them.

Fallout 3 weapons

 * † Damage is not affected by Demolition Expert
 * Damage calculated under Demolition Expert (3 Ranks)

Disarming
Your Explosives skill determines how close you can get to mines before they detect you, as well as how long the mine will take before it explodes. There does not appear to be a minimum Explosives skill necessary to disarm a mine, so long as you can run up and activate it fast enough. But if you're slow or your skill is too low, it will blow before you can do that.

Specific levels of Explosives are required to disarm certain explosive-based traps. The Repair skill is used to disarm any trip wires or pressure plates associated with traps.
 * 25 is required to disarm Megaton's atom bomb.
 * 30 is required to disarm hanging Grenade Bouquets
 * 45 is required to disarm Rigged Computer Terminals
 * 60 is required to disarm Rigged Baby Carriages

Slave collars are also disarmed with Science skill (level 65 required).

Increasing Explosives skill

 * Bobblehead - Explosives (permanent +10)
 * Little Leaguer (permanent +5 for each rank)
 * Duck and Cover! (permanent +1 or +2 with Comprehension)
 * Raider Blastmaster Helmet (temporary +5)
 * Torcher's Mask (temporary +5)
 * Takoma Park Little Leaguer Cap (temporary +5)
 * Bombshell Armor (temporary +10, requires The Pitt)

Explosives in Quests

 * 25 Explosives is required to interact with Megaton's atomic bomb.
 * 50 Explosives is required to train the residents of Big Town in placing a minefield during Big Trouble in Big Town.
 * High explosives can cause Reilly to reveal that her rangers left mines to slow down the mutants during the Reilly's Rangers quest.
 * Explosives is used in conjunction with Science to disarm any Slave collars on escaping slaves, though the dialog option is misleading on this point, only mentioning science as the required skill.

Previous games
In Fallout, Fallout 2 and Fallout Tactics, the character’s ability to throw a grenade is directly related to the Throwing skill. The character’s ability to set or disarm an explosive is related to the Traps skill.