Voltage drop is the amount of voltage loss in a circuit as a result of impedance. Any component that caries current is subject to resistance or impedance to current flow. Because LEDs need very low voltages to function, any loss in voltage can alter the color or brightness of illumination and can also cause the LED to flicker.
1)Determine your input voltage.
2)Determine your wire run length.
3)Determine the material of wire (assume copper in most cases).
4)Determine the proper wire gauge against resistance (AWG value).