Wrong Wire

"Riggs: Rog?

Murtaugh: Yeah?

Riggs: Grab the cat!"

- Lethal Weapon 3

A sub-trope of the Wire Dilemma, cutting the Wrong Wire will very often simply speed up the countdown to detonation or, for some reason, jump it ahead an arbitrary amount, typically just enough time to pull out a Million to One Chance at salvation.

Of course, this would realistically require a far more exotically-designed detonator than most would bother with. In reality, cutting the Wrong Wire would usually either cause an instant detonation, or do absolutely nothing.

In point of fact, the easiest to make, and by far most reliable bombs only have two or three wires: a positive and a negative to the ignition switch, and perhaps a ground. Cutting either of the non-ground wires would logically disable the bomb, since without power to the ignition switch, there's nothing to trigger the detonator, and the ground wire would do absolutely nothing. Of course, any terrorist would know this, and would start thinking of countermeasures to stop a bomb squad. And if the bomb maker starts to enjoy the "game" too much, they might be willing to risk the bomb being disarmed Just in Time, just to rub their superiority in their enemy's face.

Of course, there is one particularly good reason to build a detonator with wiggle room; if the bombmaker screws up while assembling the bomb, they thus have time to correct that screwup before it kills them. And just in passing, cops and soldiers have a good hard laugh and a round of drinks whenever an NGO bomb-maker gets Hoist By His Own Petard.

Anime and Manga
"Minnie-May: Oh Crap! The power cut off and the power-off switch cycled! We've got ten minutes before it blows!
 * In Gunsmith Cats, bomb-maker Ken Taki uses Wrong Wires for safety reasons, and has become more safety-focused recently as he has early stage multiple sclerosis, but was forced by The Syndicate to keep making bombs despite having a degenerative nerve condition that made his hands shake uncontrollably under stress.

Rally: Why use a timer when the power's cut? Why not just, "Boom?"

Ken: Hey, everyone makes mistakes, huh? And I like living!"

Film

 * The Shadow: In The Movie, a colorblind scientist cuts the wrong wire on the nuclear bomb, making the timer go to warp speed. By the time he's reconnected that wire to fix it, he's gone from having hours to having about two minutes.
 * In Lethal Weapon 3 the use of this trope leads to the memorable "Grab the cat" line.
 * The climax of the mid-90s Denzel Washington vehicle Virtuosity looks like a straight example of this trope, with a virtual recording of the now-dead antagonist mocking every wrong choice thrown in for flavor....

Literature

 * The famous 'Dan Brown Did Not Do the Research' ending of Digital Fortress does this with a computer virus, accelerating the destruction when the wrong password is entered.
 * In The Frogmen by Robb White a Drill Sergeant Nasty at the Navy's frogman school becomes infamous for the fiendish tricks he puts in his training mines. Unfortunate trainees who fail receive a shock.

Live Action Television

 * The pilot for MacGyver has one of these in its opening scene, prompting him to get out a paper clip and do his thing for the first time in the series.
 * In Eureka, a doomsday machine jumps from 20-something hours to 7 hours when the wrong wire is cut. See the entry in Wire Dilemma.
 * A similar situation (not with wires, but close enough) occurs in the Stargate SG-1 episode "Serpent's Venom", where Carter and Daniel have to enter a combination code into a mine in order to reprogram it, but they enter the wrong code, resulting in a countdown starting up (as this is the defense mechanism put in place on the mine so it wouldn't be tampered with.)
 * An episode of CSI had a bomb tech disarm a bomb, only to discover that it has come back on. He disarmed a decoy bomb and this activates the real trigger mechanism. The bomber specifically designed the bomb to kill the cops trying to disarm it and was playing games with them.

Western Animation

 * Justice League uses the "wrong wire speeds up the countdown" method in the episode "Wild Cards." Justified because the Joker built the bomb in question, and it turned out to be a fake anyway.
 * Happens more than once. This becomes an Overly Long Gag which The Flash is happy to "run with it".
 * On Archer, cutting the green wire of a bomb speeds up the timer, because Archer misread the bomb's serial number to their bomb expert. M... as in Mancy?

Video Games

 * The classic point-and-click adventure game Discworld 2: Missing Presumed...? further spoofs the above Lethal Weapon 3 example in the intro, with Rincewind and the Librarian standing in for Riggs and Murtaugh. This being Discworld, the Clock Punk bomb three flasks of mysterious bubbling liquid, rather than wires.
 * A variation occurs in the Playstation/N64/PC game based on Spider Man, where a group of terrorists have set up a massive bomb in a bank: the player has to pick up the bomb and carry it over to an explosion-proof safe, but dropping the bomb at any point speeds up the countdown.
 * In Bomb Squad, incorrectly replacing a piece will cause the Magic Countdown to speed up until you remove it. Cutting the wrong piece causes the bomb to explode unless you quickly resolder it.