I just moved into a new apartment and I would like to install simple ceiling light. As shown in the picture, there are two wires outside the ceiling, a blue one and a red one.
The light switch button is on the wall. When I install light in other rooms, if I switch off by pressing the power button on the wall, the electricity tester does not beep at all. Only when I switch on the power, the electricity tester makes an audible beep. But for the wires in this room, no matter the light switch is on or not, the my test makes a beep all the time, as shown in the picture.
Now I have the following questions:
What could be the potential problems? Some wires are connected improperly?
When I install a bulb to the light fixture (the black thing in the picture), the bulb doesn't light up? Why? As I said, there is always voltage detected, but why doesn't the bulb light up? I've checked the bulb is in good condition.