The answer to 'junction box dimming lights' is that there are several common causes for dimming lights in a junction box, including loose connections, outdated wiring, overloaded circuits, and issues with the dimmer switch itself. Symptoms may include flickering, dimming, or complete loss of light.
To troubleshoot, first check the connections in the junction box to ensure they are tight and not loose. If the wiring is old or outdated, it may need to be replaced by a professional electrician. Overloaded circuits can also cause dimming, so try reducing the number of lights or devices on that circuit. Finally, the dimmer switch could be faulty and may need to be replaced.