Short Answer: You have a red-tipped flasher bulb installed in a socket or the wiring is faulty. The flasher bulb will only cause the circuit it is a part of to flash on and off. If your light string has multiple circuits then that’s the reason only a portion is flashing.

Longer Answer: Take the following steps to determine what is happening with your light set.

1. Find and replace the red-tipped bulb that someone installed in your light string with a standard replacement bulb.

2. Install another red-tipped flasher bulb in the circuits that are steady on and then the light sections will flash on and off. Since they won’t be synchronized and they flash rather than twinkle – the entire set goes on and off not individual bulbs – this type of configuration is best installed in a way that randomizes the flashing. (Like wound on a hedge or wrapped in a Christmas tree.)

3. Your plug end is not making good contact in your outlet. Solve this problem by first gently squeezing the two prongs of the plug closer to one another.

4. After checking steps 1-3, if these steps don’t answer the question then wiring in your set is more than likely the cause. Unfortunately, it’s time to replace the set of lights. These types of breaks in the wiring most commonly happen during installation and storage. Be kind to your lights and try not to pull or tug them.