Xindak FP-Gold

In case my description of a circuit tester was too confusing. Here is a link to a typical example. There are many brands and they are readily available at any hardware store. There are also models that will test a GFI outlet.

http://www.tripplite.com/shared/img/products/large/ct120.jpg

A good way to check polarity on power cords is to use a burn-in adapter and polarity checker. The burn-in adapter fits into the IEC end and allows the user to connect the power cord to a standard electrical device (lamp, fan, etc.). The polarity checker is an inexpensive ($5-8) device from your local hardware store. It is meant to plug into a wall outlet (in this case the burn-in adapter). The unit has several LEDs that light up. Depending upon the color and sequence it specifically identifies any problems (which wires are reversed, open hot/neutral/ground, etc.)

It is a very handy and inexpensive device that has found more than one wiring error for me. If you use it to check a power cord make sure to check the wall outlet first.