Light emitting diode (LED) lights are mixed with incandescent lights in a light string, e.g., for Christmas or other holiday season lighting. In an incandescent light string, such as a mini-light string, in which the incandescent lights are wired in series, LED lights are wired in parallel in one or more groups which are in turn wired in series with incandescent lights in described light string circuits. The LED lights may be provided in the form of an add-on LED light string, or "piggy-back" light string, that for its power supply connects with an empty bulb socket in an incandescent light string. An incandescent flasher bulb may be incorporated into the LED light string to provide surge protection as well as to enable flashing or twinkling of the LED lights. Surge protection may also be provided by an electrical shunt, e.g., a semiconductor shunt, incorporated into the LED light string, or incorporated with the associated empty bulb socket as part of the incandescent light string.