Voltage fluctuations and flicker are two separate issues. Voltage fluctuations are simply a change in the voltage level of an electrical current. This can be caused by several factors, such as a change in the load on the circuit, a change in the electrical supply, or a problem with the wiring. Flicker, on the other hand, is a change in the brightness of electrical light. This is usually caused by a change in the voltage level and can be very annoying, especially if it is constant.