An incandescent light bulb is an example of a linear load. When a non-linear load current goes up or down, there is not a corresponding, proportional change in the voltage. Examples of non-linear loads include fluorescent light ballasts and computer power supplies. Also known as an Interruption. Instead of current flowing to equipment, it is diverted directly to a ground or the earth.
Voltage is analogous to water pressure.
It is the difference in water pressure that creates flow in a pipe. Small businesses typically receive voltage from Duke Power in the range of 120 to 480 volts.