Wiring – How to wire in the replacement fluorescent light fixture


The electrician installed a new wall switch in the kitchen, so that when I replace the fluorescent light, it can be turned on and off at the wall switch.

I am ready to install the new light.

In the ceiling, there is a bare copper wire that I am assuming is the ground and will be wired to a screw on the light fixture. There is a white wire – neutral, and a black wire- hot, and I know to wire white to white and black to black.

However, there is a second white wire and a second black wire, and they are wired together with a cap on them, and I am not sure how to connect those.

Also in the ceiling is an old two-pronged plug where you could plug something in, although I am not sure what you would ever plug in there. But perhaps the second black and white wires are for that plug, and the electrician just capped them together temporarily because they come from the same outlet.

So do I just connect all three whites and all three blacks together?

Best Answer

Most likely the second white and second black wires are the connection to the switch itself. If so, then what you've got is power line from circuit box to light, switch line from light to switch. (The alternate method is power line from circuit box to switch, switch line from switch to light - which would have been less confusing for you but he probably was dealing with old work by the sound of it.

How it works in your configuration (if I'm right) - imagine the electrical current like a flow of water. The power comes in from the breaker box on the black line (aka the hot line). The power then runs to the white line and down to the wall switch. When the switch is on it then runs back up the black line to the light. You connect black to black, and the power flows into the light, then out the white line. You connect white to white, and the power flows on down back to the breaker box, and out.

So - don't touch the second white and black. Just wire the light's white to the lonely white and black to black the same way.