Old wiring

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  #1  
Old 11-29-20, 10:53 AM
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Old wiring

I just opened my ceiling to install a light fixture and this is what the old electrical looked like. The wire on the right and left are hot. I am assuming the left is the ground, middle is neutral and right is hot. Does this sound right? And does anyone know what size bolts would attach to it?
thanks

<img src="https://cimg3.ibsrv.net/gimg/www.doityourselft.com-vbulletin/451x381/cl_30ba3e715e36c1a4ea47f7ed1257af1f821dbb62.jpg" width="451" height="381"/>
 

Last edited by PJmax; 11-29-20 at 11:15 AM. Reason: cropped/enlarged pic
  #2  
Old 11-29-20, 11:13 AM
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Welcome to the forums.

What was there ?
Was something connected ?
There is no ground wire there.

That is an old gas fixture box. It may only have the large center pipe that requires a fixture bar and nut. It looks like there are three cables there.

A - looks to be switched hot to the light.
B - looks like the neutral to the light,.
C - looks like always live/before switch.

This is a similar box to yours. I can't see in your box. The center piece is what holds the fixture up. It gets an extension called a hicky and then a fixture bar.
<img src="https://cimg0.ibsrv.net/gimg/www.doityourselft.com-vbulletin/410x355/oldbox_389e8809574aa7f171ca4f2cca710dd0aa92b6ec.jpg" width="410" height="355"/>
 

Last edited by PJmax; 11-29-20 at 11:31 AM.
  #3  
Old 11-29-20, 12:31 PM
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There wasnt anything there. It was just covered. There is a threaded post in the middle so it looks like that is probably the easiest way to connect it.
thanks
 
  #4  
Old 11-30-20, 02:55 PM
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I opened it up a little more and it seems like the wire on the right is the only hot wire. Any ideas what is what? Also the wire in the middle and on the right are two wires spliced together.
thanks
<img src="https://cimg0.ibsrv.net/gimg/www.doityourselft.com-vbulletin/940x2000/screenshot_20201130_155416_gallery_3f1137ac7b68423c8dc732b126565cb9d0dc9d50.jpg" width="940" height="1985"/>
 
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Old 11-30-20, 06:34 PM
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Be very careful...... that insulation will crack from age. If it cracks where it enters the box you'll have a short that is almost impossible to fix.

Are you saying that the wire I traced red is one wire ?
There should be an even number of wires in the box. 2, 4, 6, etc.
<img src="https://cimg0.ibsrv.net/gimg/www.doityourselft.com-vbulletin/624x367/wxw_f02fca65a5cfa1b9d995ffd32a231903f7640108.jpg" width="624" height="367"/>
 
  #6  
Old 11-30-20, 07:44 PM
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No there is actually 5. The one on the Left has one, the one in the middle is 2 spliced together and the one on the right has 2 spliced together.
 
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Old 11-30-20, 09:48 PM
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If there is 5..... one was cut off or broke off.
So the second picture is the same as the first. Nothing looks different.
I explained what the wiring looked like. Is that not correct ?

You had originally said the left and right wires were hot.
Then just the right wires were hot.
As I posted...... it would appear the right hand wires are hot.
The left hand wired is switched.
The center wires are neutral.
 
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Old 11-30-20, 10:32 PM
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Thanks for the replies.
So how would the switched wire be connected?
 
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Old 11-30-20, 10:50 PM
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Isn't there a switch in that room ?
Typically there would be if there was a ceiling light.

There would be a two wire cable down to the switch. One wire would connect to the always hot wire and the other wire would be the switched hot to the light. You could just have two cables there..... a three wire and a two wire cable. That would explain the five wires.

Just be careful working with this older wiring. As I mentioned.... just moving the wire around can cause the insulation to crack and fall off.
 
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Old 12-01-20, 08:22 AM
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You could just have two cables there..... a three wire and a two wire cable. That would explain the five wires.
If the house wiring is knob-and-tube there could be a fifth wire and not cables. The gas fitting box and the age of the wire insulation suggests that it might be knob-and-tube.
 
  #11  
Old 12-01-20, 09:13 AM
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It looks like old knob and tube. There could be five wires.
 
  #12  
Old 12-02-20, 04:51 PM
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How would I wire it since there is 5 wires?
 
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Old 12-02-20, 05:23 PM
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Check from A to B and A to C. One of those pairs should give to 120v when the switch is on.
 
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Old 12-03-20, 10:21 PM
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Today I tried A and c to the hot wire of the light and B to the neutral wire of the light. The light came on but the switch didnt work.
 
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Old 12-03-20, 10:31 PM
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Check from A to B and A to C. One of those pairs should give to 120v when the switch is on.
Did you do this ?

It doesn't say to connect A to C.
If A is switched and C is always live..... connecting them together will keep the light on.
 
  #16  
Old 12-04-20, 11:40 AM
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Be Careful!

First, as others have said, this old wiring becomes very brittle with age, and will crack exposing bare wire and will leave you with a real mess. And that can be a real issue with one of the options that may exist that I will explain below. It also sounds like you are trying to figure out this problem without a volt ohm multimeter. If that is the case, stop and get one immediately; $7.00 at Harbor Freight.

As PJmax recommended, “Check from A to B and A to C. One of those pairs should give to 120v when the switch is on.” I would hope and expect that A to B will be the pair that will allow the light to operate with the switch. That means A will become “hot” when the switch is on. One leg of the fixture will then connect to A and the other to B.

Now if A and C allow the light to operate with the switch, you have a problem. Since you said C is hot, and if A and C allow the light switch to operate the light, this means the light has a hot wire to it all the time, and the switch connects the fixture to the neutral wire. That is against normal practice and I think against code. The light will actually operate that way, but when a light switch is off, the light fixture should have no hot wire going to it.

Assuming you do find A and C to be the “correct” pair, it is likely that one of the B wires goes to the switch as does A. If this is the scenario you find, you will need to separate the B wires, and use the multimeter ohm setting to check continuity between A and each separate wire of B when the switch is turned on. If you do find that one of the B wires does go to the switch, you should connect that wire to C, and then one leg of the fixture goes to the remaining wire of B, and the other leg of the fixture goes to A. This is the area that if this is the scenario you find, the wire insulation will be a huge problem as you will be working the wires and likely to have bare wire issues.

Now sometimes the wiring in these old houses is very confusing an not even close be logical. For instance, if you find A and C to be the “correct” pair, and neither of the B wires go to the switch, then the person who wired the switch could have wired the light with a hot wire, then ran the switch to a neutral wire that did not go to the light box. If that is the case, a lot more investigation will be required. In any case, if A and B are not the correct pair, and you are not comfortable and knowledgeable about electricity, you may want to call an electrician.

This old wiring is not usually grounded, but I have come across houses where a bare ground wire is run through the house and connected to each metal box with a clip that goes to a water pipe or the electrical box. If you see a clip on one of the front edges of the box, you probably have a grounded box, and the ground wire of the fixture should be clipped or screwed to the metal box. If not, just be mindful that your house has non-grounded fixtures and probably non-grounded outlets.
 

Last edited by MR Engineer; 12-04-20 at 12:19 PM.
 

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