220 volt has 2 lines that are hot, a common & a ground,:) does it matter which hot line is connected, what is reverse polarity and is there a sure way of preventing it

Line1 is normally Black and Line 2 is Red.

240 volts can even be both blacks(reds or other colors). The 2 hots doesn't matter which to which. Reverse polarity is on 120 volt recepticles.
If you reverse polarity on battery or DC motor it will rotate backwards. Reversing the 2 wires on AC wiring won't reverse a motor.

Moved per report

First off, there is NO "220" any more. This has been gone for MANY years. Folks still have the old "220" mentality though. The movie "Mr. Mom" didn't help this mistake with the classic quote "220... 221... Whatever it takes."
Residential electric is 120/240v.

Also, a 240v circuit is NOT "2 lines that are hot, a common & a ground". It is two hots and a ground.
A circuit with two hots, a neutral and a ground is a 120/240v circuit such as an electric dryer or electric range.

Quote:

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Originally Posted by donf

Line1 is normally Black and Line 2 is Red.

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Not true! :)

Question:

If I wire nut line 2 to the black wire, and line 1 to the red wire--what's the result