When your wiring starts to malfunction, it can be difficult to determine when it needs to be repaired, and when it should be replaced. Some signs that can indicate you need to install new wiring are: You have bad wiring connections. You notice the lights dimming or brightening periodically. You notice the lights flickering. You notice the odor of burning plastic. You see sparks, flames, or smoke. You notice the wires start to overheat. You notice scorching around or behind the faceplate.