View Full Version : Wiring a light in the middle of a circuit (help)
madprops
Dec 7, 2013, 06:55 PM
OK ill jump right into it.
In the box on the celling I have 3 different wire groups one comes from the light switch and has a red, black, white and bare ground the other two just have black, white and bare ground. Of those two one goes to a light in the same room (and is on the same switch as the one I'm going to hang from the box) and one is for power going to the rest of the circuit.
My girlfriend tried to change the light before I got home and I can't figure out how it was connected before. There is supposed to be two lights on the same switch with power continuing to the rest of the circuit
I made a little pic but I'm not sure how to post it. I can e-mail it to you if your willing to help
Cheers
Darcy Hinds
hkstroud
Dec 7, 2013, 07:39 PM
3 different wire groups
Wire groups are called cables.
other two just have black, white and bare ground
Called a 2 conductor cable. Called 2 conductor because the bare ground is not a conductor, it's a ground. Some people will say 2-wire but technically incorrect. Usually referred as 14/2 or 12/2, the 14 and 12 referring to sized of the conductors. Proper name is 14/2 with ground.
red, black, white and bare ground
3 conductor cable
Remove switch from box. You need to know which wire goes through the switch and which does not. You should find a 2 conductor cable (black and white) and a 3 conductor cable (black, red and white). The whites (neutrals) of the two cables will be connected together. The black of the 2 conductor will be connected to the switch and to either the black of the 3 conductor or the red. Most likely the black. The other wire of the 3 conductor, either black or red, most likely red, will be connected to the switch. That is your switched leg.
At the ceiling box, connect the whites (neutrals) of all the cables and the white to the light fixture together.
Connect switched leg (red or black) of the 3 conductor with the black of the light fixture and with the black of the 2 conductor going to the other light.
Connect the unswitched leg (red or black) of the 3 conductor to the black of the 2 conductor going to the remainder of the circuit.
madprops
Dec 7, 2013, 11:04 PM
It looks just like in the diagram you posted except the light is going right on the main box with all the wires in it (but it was easy enough to see how it was to be hooked up). I have hooked it up and it still doesn't work. I have power going to the rest of the circuit but the to lights will not turn on. When I put my volt meter on the 3 white wires and the red/black wires that are hooked up it reads 0.00 it also reads 0.00 at the other light that's on the same switch. I put my volt meter on the setting so it beeps if the circuit is complete and I put it on the same ones that read zero and it beeps so I know there are no broken wires. I also tested the light fixtures and light bulbs and they are good to go to. Photos are below. What do I do next?
madprops
Dec 7, 2013, 11:06 PM
Wire groups are called cables.
Called a 2 conductor cable. Called 2 conductor because the bare ground is not a conductor, it's a ground. Some people will say 2-wire but technically incorrect. Usually referred as 14/2 or 12/2, the 14 and 12 referring to sized of the conductors. Proper name is 14/2 with ground.
3 conductor cable
Remove switch from box. You need to know which wire goes through the switch and which does not. You should find a 2 conductor cable (black and white) and a 3 conductor cable (black, red and white). The whites (neutrals) of the two cables will be connected together. The black of the 2 conductor will be connected to the switch and to either the black of the 3 conductor or the red. Most likely the black. The other wire of the 3 conductor, either black or red, most likely red, will be connected to the switch. That is your switched leg.
At the ceiling box, connect the whites (neutrals) of all the cables and the white to the light fixture together.
Connect switched leg (red or black) of the 3 conductor with the black of the light fixture and with the black of the 2 conductor going to the other light.
Connect the unswitched leg (red or black) of the 3 conductor to the black of the 2 conductor going to the remainder of the circuit.
I hit answer but I meant to hit reply
hkstroud
Dec 8, 2013, 12:41 AM
I put my volt meter on the setting so it beeps if the circuit is complete and I put it on the same ones that read zero and it beeps so I know there are no broken wires
I of course don't know what meter you are using but I'm pretty sure that not correct. It sounds like you have set you meter to resistance measuring. That setting is marked by the Omega (little horse shoe symbol). On that setting the battery in the meter sends low voltage current through the leads and the connecting wires. If the circuit is complete, the resistance of the is shown on the display and on some meters an audible sound is made. That tells you the resistance and the continuity of the circuit. If the circuit is not complete infinite resistance is shown.
Never connect you meter to a live circuit when on that setting. You will damage the components of the meter.
Set the meter to the ac setting, usually designated by a wavy line. Set the meter to some number greater than the expected voltage (120).
Do a voltage check between the bundle of white wires and the two black wires twisted together, should read 120V.
Do a voltage check between the bundle of white wires and the red and black twisted wires, should read 120V with switch on. Should read 0V with switch off.
Wiring looks correct in ceiling. Pull wires out of switch box so I can see them. From what I can see now they also looks correct. They should not have been changed.
Wiring is correct if power comes to the switch, goes to the remainder of the circuit through the black wire and to the light through the switch and the red wire. Wiring is also correct if power comes to the ceiling, goes to the switch and to the remainder of the circuit through the black, and returns to the light on the red.
That leaves the switch itself. Using the quick connect holes in the back are known to develop bad connections. Remove the wires and put them under the screws.
madprops
Dec 8, 2013, 12:57 AM
I of course don't know what meter you are using but I'm pretty sure that not correct. It sounds like you have set you meter to resistance measuring. That setting is marked by the Omega (little horse shoe symbol). On that setting the battery in the meter sends low voltage current through the leads and the connecting wires. If the circuit is complete, the resistance of the is shown on the display and on some meters an audible sound is made. That tells you the resistance and the continuity of the circuit. If the circuit is not complete infinite resistance is shown.
Never connect you meter to a live circuit when on that setting. You will damage the components of the meter.
Set the meter to the ac setting, usually designated by a wavy line. Set the meter to some number greater than the expected voltage (120).
Do a voltage check between the bundle of white wires and the two black wires twisted together, should read 120V.
Do a voltage check between the bundle of white wires and the red and black twisted wires, should read 120V with switch on. Should read 0V with switch off.
Wiring looks correct in ceiling. Pull wires out of switch box so I can see them. From what I can see now they also looks correct. They should not have been changed.
Wiring is correct if power comes to the switch, goes to the remainder of the circuit through the black wire and to the light through the switch and the red wire. Wiring is also correct if power comes to the ceiling, goes to the switch and to the remainder of the circuit through the black, and returns to the light on the red.
That leaves the switch itself. Using the quick connect holes in the back are known to develop bad connections. Remove the wires and put them under the screws.
I'm sure my meter is set to the right mode I have shown you the reading I'm getting with the switch both on and off (in the photo bellow). I have also attached a photo of the switch with the wiring pulled out. I put my volt meter on the to screws and it reads 120 so the stabs into the back are hooked up good. What could be causing me to get zeros on my volt meter? Thanks for all the help by the way
hkstroud
Dec 8, 2013, 01:09 AM
Do voltage check between the black on the switch and white. Should only get 120 volts between screws if switch is off and at least one light is completely connected.
After voltage check between black and white, do voltage check between the red and white with switch on.
Make sure meter leads are connected to common and to voltage.
madprops
Dec 8, 2013, 01:13 AM
That leaves the switch itself. Using the quick connect holes in the back are known to develop bad connections. Remove the wires and put them under the screws.
I tried this and it WORKED!! How bad was my luck that it was nothing my girlfriend did and something that just happened. She is doing a huge touchdown dance right now and when she stops I owe her a foot massage :-( that's what I get for think it was her fault. The quick connection were in really deep and were a pain to even get out. How could they just stop working? We didn't even open the switch till today.
Thank you very much for your time and well thought out replies. I think I'm going to come on here more often as I fix up my house! You're the best!!
hkstroud
Dec 8, 2013, 01:28 AM
How could they just stop working?
When you stick the wire in the hole, it is held in by the end of a little spring. There really isn't much surface contact. Over time the surface of the wire can tarnish and form a insulating surface.
Electricians love the quick connects because they are fast and easy. Over time, usually 5-7 years, bad connections begin to develop.
Now you can begin going through out your house and remake all the connections. Believe me they will begin showing up.
Just an after thought,
Remember that when you do a voltage check you are measuring the difference in voltage between the two conductors. What you meter was telling you was that you had 120 volts on one screw and nothing on the other, because of the bad connection. Had there not been a bad connection, the meter would have read 0 volts.