When the cartridge is connected, the light in the next room disappears
I connect the lampholder in the hall, the light disappears in the next room, remove the lampholder, the light appears in the next room! What to do?
And why are you connecting a cartridge with a light bulb, not in the power distribution box by accident? Maybe you connect in series with the lamp of the next room? I can’t give a more extended answer, since you did not describe the situation in detail.