Troubleshooting low voltage in receptacles

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  #1  
Old 08-02-15, 10:22 PM
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Troubleshooting low voltage in receptacles

I have been having a problem with some receptacles in my master bedroom. I will try to provide as much information here as I can, apologies if it's too much!

The master bedroom has 4 receptacles, I recently replaced all of them (along with every other receptacle and light switch in the house) and wired them with the screw terminals instead of the back stab connections they all had before. Before I did that, outlet #4 was only intermittently working. After I replaced them, it worked fine for several weeks.

Last week we had construction outside our house, and outlet #4 stopped working (#2 and #3 are rarely used). Around the same time (it may have been the same day, we're not sure), outlets #2 and #3 in the room stopped working (I tested them with a voltage tester and there was no reading). My assumption was a loose connection somewhere had caused this.

I checked all the receptacles visually and all looked fine. When I turned the breaker back on, they still didn't work (voltage tested again). A few hours later, they started working again and worked for a few days. Then yesterday, #2 #3 and #4 stopped working again. I checked all 4 outlets with a receptacle tester. #1 showed correctly wired. 2-4 showed nothing (I assume this means not enough power to even light the tester).

I removed all the receptacles and checked the wiring. I found that #1 had a couple of wires (2 hot and 1 neutral) that I guess the person who last wired them had nearly cut when stripping them. When I pulled them, they just broke. I restripped and reattached the wires. When I turned the power back on, all 4 outlets showed correctly wired according to the tester, but 2-4 would not power on a table lamp (same lamp worked in #1). I tested with a voltage tester and got 35v hot to neutral in 2-4, and 118v in #1 (I am estimating as my multimeter is analogue), and 120v ground to hot in all 4. Based on this, I thought the problem was a neutral connection somewhere between (or at) #1 or #2.

I removed all the receptacles again and checked them. I am confident that they are all wired correctly and there are no loose wires.

Additional information: This circuit also has a light and extractor fan in the bathroom, and a ceiling light and 2 receptacles in another bedroom on it, in addition to the 4 receptacles and ceiling light in the master bedroom. At no point has the breaker tripped, and all the outlets further up (I assume) the circuit have not had any issues. I did check the ceiling lights, as we had a light fixture downstairs with an open neutral that caused problems, it appears to be working fine.

Does anyone have any suggestions on how to troubleshoot this further? I do not have any kind of circuit tracer device, but I'm wondering if there may be an issue with the neutral somewhere between the boxes?

thanks for reading this far!
 
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  #2  
Old 08-02-15, 11:19 PM
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I'm wondering if there may be an issue with the neutral somewhere between the boxes?
Unlikely. You are going to need to check every box on the breaker and move every back stab to the screws. Usually outlets are wired in order but you may have a light or receptacle that seems to be upstream of the problem but is actually down stream. While it may work correctly the feed from it to the next may be bad.
 
  #3  
Old 08-03-15, 05:28 AM
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Id you do some electrical work somewhere in the house just before the receptacles stopped working?

Do all the receptacles elsewhere in the house work correctly with a 100 watt or more incandescent light plugged in and switched on??

Redo your voltage measurements with the incandescent light plugged into the other half of the same receptacle.

Tighten up all the screws and set screws in the panel (except the big lugs for the fat service wires). Switch off each breaker before touching the screw on it.
 
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Old 08-03-15, 08:16 AM
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I tested with a voltage tester and got 35v hot to neutral in 2-4, and 118v in #1 (I am estimating as my multimeter is analogue), and 120v ground to hot in all 4. Based on this, I thought the problem was a neutral connection somewhere between (or at) #1 or #2.
The problem is a neutral connection somewhere in the circuit. It's not likely the problem would be bewteen any 2 boxes.
 
  #5  
Old 08-03-15, 08:45 AM
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@ray2047 - I did already move all back stab to screws, but will definitely check the other things on the circuit, including the light fixtures. Thanks

@AllanJ - no, there was nothing done since I replaced all the switches, which was probably a couple of months ago. I haven't tested the things on other circuits, but we did test all the outlets on that breaker with a hairdryer on full power and all the ones outside the master bedroom worked fine. I will try the voltage test as well to see if that sheds any light. I do not really want to touch anything on the panel except as a last resort, but will bear it in mind.

Thanks for the replies all! Will report back soon.
 
  #6  
Old 08-03-15, 09:18 AM
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Remember to redo all wire connections not just look.
 
  #7  
Old 08-03-15, 04:47 PM
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I took all the receptacles out and rewired them, and the same with the light switches. That didn't make any difference, however while I was doing that, I found an old receptacle that still had the backstab wiring. I replaced that one, and now the voltage is at ~120 for all the outlets. I also tested with a hairdryer in the other half of each outlet, and the voltage only dropped a little, which I believe is normal. So I think we're good. thanks for the help all!
 
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Old 08-03-15, 07:19 PM
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Once again backstabs receive the Notorious Receptacle award. Thanks for letting us know the solution. it may help someone else.
 
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Old 08-03-15, 08:18 PM
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Notorious Receptacle award
That made me
-------------------------
 
  #10  
Old 08-06-15, 11:09 PM
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Well it looks like I spoke too soon! After working fine for 3 days, the same three outlets stopped working again today. They appear to have the same low voltage as before.

Just to recap, last time I
  • Removed and rewired all the receptacles and switches on the circuit
  • Replaced the last remaining backstab receptacle with a screw terminal one
  • Voltage tested each receptacle on the circuit with a hairdryer plugged into the other half

I have probably rewired the receptacles that aren't working at least 5 times since this problem started, and rewired all the other ones once as well. Is it possible for anything other than a loose connection to be causing this?
 
  #11  
Old 08-06-15, 11:12 PM
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Have you replaced the breaker for the circuit you are having trouble with. I am not sure if replacing it will solve the problem but it might be worth giving it a go. Is this a modern panel or is it a pushmatic type panel?
 
  #12  
Old 08-07-15, 08:28 PM
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I think you should do this next: ------ Find out the order in which the receptacles are wired. One at a time unhook the hot wire from a receptacle. Then test all of the receptacles to see what does not work. That is, no voltage as opposed to low voltage. Do each voltage test with a light or hair dryer plugged in and turned on. Write down your findings. Then reconnect that receptacle and unhook the hot wire from a different receptacle. Etc.

With all of the information you have thus collected you should be able to figure out the order the receptacles are wire. ou want to find the last good receptacle and the first bad receptacle.
 
  #13  
Old 08-24-15, 11:59 AM
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Apologies for the delay in responding, I wanted to be sure I had this fixed before replying again!

Thanks AllanJ - I tested the outlets and was able to confirm that the order of the circuit was what I thought, therefor the problem was between outlets 1 & 2.

I checked all the wires in both boxes, and was able to find a small hole in the insulation in one of the neutral wires in outlet 1. When I stripped down to this hole, the wire was partly broken. Luckily, once I clipped this broken piece out, there was still enough wire to properly connect the receptacle.

I tested all the receptacles after doing this, and the voltage was good for all of them. I then tested again every day until yesterday (1 week) to ensure there was no voltage drop and the outlets still worked. So this time I'm pretty sure everything is fixed.

I can understand why a fault in the neutral out of outlet 1 would affect the voltage in the outlets further along the circuit. What I'm not exactly clear on is why a small fault in the wire would cause a large drop in voltage, and also why the outlets initially had voltage, then it dropped back off again. If anyone has any suggestions on these, it would be much appreciated.

Thanks everyone for your help and patience!

M
 
  #14  
Old 08-24-15, 12:22 PM
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Another test when yo find the order of connection is to go to the last working one and bypass the receptacle. White to white, black to black. Disconnect the cables at the next receptacle and see if either cable show ~120v.
What I'm not exactly clear on is why a small fault in the wire would cause a large drop in voltage
If you are using a digital the real reading is probably ~0 volts. You are just seeing capacitive or induced voltage. An analog multimeter would probably show ~0. If you are using a digital meter you are literally chasing ghosts that aren't real.
 
  #15  
Old 08-24-15, 06:27 PM
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Thanks Ray! I will definitely use that suggestion of bypassing the receptacle if I have any more problems. I am using an analogue multimeter, which showed ~30v. It was enough to light a receptacle tester, but not enough to light a bulb.
 
  #16  
Old 08-24-15, 06:37 PM
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Definitely a puzzler but I have had them too.
 

Last edited by ray2047; 08-24-15 at 06:56 PM.
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