How do I know which wire is hot and neutral?
The hot wire is always smooth on the outside of the cord, while the neutral wire is ribbed on the outside. For flat cords with polarized plugs on the end, the larger prong (or terminal) is the neutral wire.
Is the neutral wire marked?
In most modern fixtures the neutral wire will be white and the hot wire is red or black. In some types of fixtures, both wires will be the same color. In this case, the neutral wire is always identified by some means. In some cases, there will be small writing on the wiring case.
What happens if you mix up hot and neutral wires?
This happens when the hot and neutral wires get flipped around at an outlet, or upstream from an outlet. Reversed polarity creates a potential shock hazard, but it's usually an easy repair. Any $5 electrical tester will alert you to this condition, assuming you have a properly grounded three-prong outlet.
Does the neutral wire have ridges?
With power cords, an electrical wire that is totally smooth on the outside is the hot wire, which is then connected to the smaller terminal or prong on the plug. When you see wires with ribs or ridges, these are the neutral wires.