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Mike G.
Mike G., Master Electrician
Category: Electrical
Satisfied Customers: 7590
Experience:  Proven Professional 48 years Experience
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I want to install a ceiling fan/light fixture in an existing

Customer Question

I want to install a ceiling fan/light fixture in an existing ceiling light fixture. When I removed the old light fixture there were only two black electrical line inside the junction box. One black line is thicker and it registers 240 volts and the other thin line is 120 volts when tested with voltage meter. Is this a problem or should I have it checked? The house was built in the 1940-50s.
Submitted: 2 years ago.
Category: Electrical
Expert:  Mike G. replied 2 years ago.

Hi, I'm Mike G and I'll be glad to assist you. Give me the count and colors of the wires in the box.

Is it switched controlled?

Is there more than one switch?

Do you remember which wires were connected to the old fixtures?

Customer: replied 2 years ago.
There are six separate black wires (not color coded) coming through three different punch-out holes in junction box. Each opening of the three has two wires coming into the box. One individual wire was tested at 120 volt (using a multi-meter); another wire (spliced with another separate line from the opposite side of the box) was tested at 240 volt. The other three lines were tied together and wrapped in electrical tape. There is a single-pole switch that controls the light and there is no other switch. When I removed the old fixture they were connected to the one 120 volt line and the two lines (taped together) which was tested at 240 volts. Hope this helps
Expert:  Mike G. replied 2 years ago.

What point were you testing to. Wire to what, wires to what?

Customer: replied 2 years ago.
I tested only the exposed two wires that were connected to the previous light fixture...Used a multmeter, one lead touched one of the exposed copper wire and the other lead to an electric cord (neutral site) that was plugged into a grounded outlet. After getting a reading I tested the other exposed line using the same method...
Expert:  Mike G. replied 2 years ago.

Retest from the single wire to the double connection, once with switch on and once with it off. Testing from a remote receptacle could and did give you that 240V reading. It did alert that the joint is the hot and the single wire is the neutral. They have the connections on the switch leg reversed. That happens alot in older home having work done by unqualified people.

Customer: replied 2 years ago.
If I (a novice) understand you correctly, place one of the leads from the multimeter to the exposed single wire and the other lead to the joint (taped) wire. This method gave me a reading of 120 volts. I made one mistake in my original narrative, the single line was 240 volt and the joint (taped-2 lines) wire was 120 volt.
Expert:  Mike G. replied 2 years ago.

OK, the wires are not reversed. Does the switch control the hot wire? If so, connect to those wires. Fan white to the 2 wire joint, fan black and blue to the single wire.

Customer: replied 2 years ago.
All I know is that when I flip the switch (single pole) in the off position it turns the light off and doesn't control anything else (including the two electrical outlets in the bedroom). The switch has only two separate lines, one is white (top) and the other is black (bottom).
Expert:  Mike G. replied 2 years ago.

That's what is supposed to do.

Customer: replied 2 years ago.
When I put a voltage tester (w/ neon light and voltage reader) on hot it did not show any power or voltage. When I placed the voltage tester on the joint wire it indicated 120 volts with the power switch on.
Customer: replied 2 years ago.
In both cases, the switch was in the off position...ignore the last three words of my last statement. The power was in the off position and not on...
Expert:  Mike G. replied 2 years ago.

You are confusing me. If testing the single black wire to a joint in the box, any joint. And getting 120V with the switch on and zero volts with the switch off. That is where you connect the fan. You have to use a 2 wire tester.

Customer: replied 2 years ago.
Sorry about the confusion...I went back to the junction box and used a simple voltage tester with two leads. With the light switch in the off position I get 120 volts with the joint wires (taped together) and no volts with the single wire; with the switch in the on position I get 120 volts with the joint wires and 240 with the single wire. Again I grounded one of the multimeter lead to an extension cord (plugged into an outlet with a three prong plug) using the neutral side of the cord.As requested, I tested both wires (joint & single) at the same time with the same tester in the off position (one lead to the joint and one lead to the single wire) and there was no power/volts but when I turned the switch in the on position the tester showed 120 volts with both wires connected with the multimeter. Hope I explained this correctly...So what I'm understanding, the single wire is the hot wire and the joint wire is neutral.
Customer: replied 2 years ago.
To confirm our discussion and my last statement, was I on the right track with what you provided? I appreciated the help with my dilemma. Customer
Expert:  Mike G. replied 2 years ago.

You're welcome.