When I purchased my rig it came with a 30 amp extension cord.  I thought “cool, that saves some money!”  Well I was wrong.  The extension cord was wired incorrectly.  Even though it had molded, professional ends on them, the person who laid the wiring in the machine cross the hot wire with the neutral wire so as soon as I used it, it popped circuits.   I could not, for the life of me figure out what was wrong.  The extension cord was the last thing I looked at!

If you examine the diagram above carefully, you will understand that the hot (red) and neutral (black) wires are wired to opposing polls.  What this effectively does is make all exterior metal surfaces that are supposed to be grounded live and a significant shock can be had if the ground wire (green) was not in place.  The neutral and ground wires are eventually crossed as a safety (such as in cases like this) to help avoid injury and potential fires.  Since the ground wire was connected properly, use of this extension cord instantly caused the circuit breaker(s) to trigger.

This is what the proper wiring should look like.  Basically if you plugged the male and female ends into each other, you’d have green, black and red loops of wires.

The moral of this story is to never just assume your extension cords are assembled properly at the factory.  The person operating the machine may have had a laps in intelligence and you could be the one to pay the price!