What is the worst problem caused by reversing the polarity?

[cloa513]

Reversing the polarity is a mainstay of science fiction but what is the worst example of incorrect wiring putting the negative into positive and reverse leading to serious electrical problems.

 

[anorlunda]

Explosion and death.

 

[cloa513]

Care to share a real example

 

[Baluncore]

“Reversing the polarity” probably refers to switching from a motor to a generator rather than “getting your wires crossed”. It suggests the direction of energy flow is reversed.

Submarine battery banks have been connected backwards. The extreme current causes a DC arc that generates a metal vapour plasma where the connection is broken very soon after the connection was first made made.

 

[phyzguy]

Here is a real example. Reversing the polarity caused a major fire. I don't think it caused explosion and death, but it easily could have if the fire had spread to the gas tank.

 

[Baluncore]

There have been examples where three phase hydroelectric power stations have connected an alternator with reversed phase rotation. The turbine blades and shaft keep going one way while the rotor windings go the other. Such examples tend to be kept quiet to protect the idiots who wired it and threw the switch.
See picture 17; http://archive.boston.com/bigpicture/2009/09/the_sayanoshushenskaya_dam_acc.html

 

[Averagesupernova]

I found the link in post #5 interesting until this:

I prefer to use something on the engine because charging that entire lump of metal is hard for a battery to do and it's physically grounded to the chassis anyway. You need to keep the ground far away from electrical brains because the bleed over from the surge during cranking can fry stuff like ABS, ECM or other powertrain computers.

Bleed over from the surge. Huh?