Lights flickering within house lamp ceiling fixture porch lights Different circuits What is problem? ...
Answers: You have a loose conection at the T-junction box. Prbably at the main breaker. The breaker may also be week and arcking. This is a thoroughly big fire hazard! I would check adjectives conections and replace main breaker but be carefull the system is still live and a shock at the major can and will kill you. So if your not comfortable working near high voltage hail as an electrician.
old electric wiring, loose wires, too many outlets on one circut