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troubleshooting electrical circuit containing 4 separate receptacles

troubleshooting electrical circuit containing 4 separate receptacles

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  #1  
Old 07-05-12, 06:54 AM
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troubleshooting electrical circuit containing 4 separate receptacles




a 20-amp circuit containing four (4) separate receptacles starting giving me problems for the first time. Receptacles #1 and #2 don't have anything permanently plugged into them. Refrigerator & coffee maker on #3, basement freezer on the end-of-run receptacle (#4). No problems for years until now.

The 1st receptacle works fine but the latter three lost power. confirmed using voltage tester on all receptacles. voltage tester says breaker is good. voltage detector found 'dead' section between 1st and 2nd receptacles so I replaced the section with same wire type (12-2 NM cable) and two junction boxes. Power restored. Thought the problem was solved until my wife called to say that the same 3 receptacles are dead again. Do I need to replace the ENTIRE cable between 1st and 2receptacles? What am I missing?

BTW, the voltage detector beeps occasionally when not even near an AC power source. Is it supposed to do that? Do I need to get a better quality detector since this one was a freebie?

Also, the voltage tester is a simple light with red and black probes. Is this adequate to use for diagnosing problems like this?
 
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  #2  
Old 07-05-12, 07:16 AM
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Have you checked all of the connections at 1 & 2? Typically, when part of the circuit works and part does not, the issue lies at either the last working or first dead receptacle on the circuit.
 
  #3  
Old 07-05-12, 07:43 AM
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BTW, the voltage detector beeps occasionally when not even near an AC power source. Is it supposed to do that? Do I need to get a better quality detector since this one was a freebie?
An all but useless device when used by newbies. They have their uses but not for serious trouble shooting. A multimeter (preferably analog*), a test light, or a solenoid tester are all good choices.

*A good quality digital meter is fine but the cheaper ones can be influenced by induced voltage. Even cheap analog meters on the other hand are not prone to induced voltage reading.
 
  #4  
Old 07-05-12, 08:23 AM
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I had replaced #1 receptacle a year ago because of cracked plastic. Those connections should be okay since it's the only one working on the circuit. Never had to do anything with #2. I'll check connections on both when I get home later today. I can only hope it's as simple as a loose connection. If connections are okay, I'm still searching for the root cause.
 
  #5  
Old 07-05-12, 08:34 AM
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none of the DIY books or online info sources mention that the voltage detectors shouldn't be used as a first-line diagnostic tool. beginning to realize that sometimes the orange big box store sells products rather than sound advice. depends on the person too.
have a Craftsman digital multimeter but you've stated that they're influenced by induced voltage. will pick up an analog one later today.
So my task list includes checking connections on #1 and #2 and using the analog multimeter to trace where the current stops.
 
  #6  
Old 07-05-12, 10:39 AM
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A Craftsman digital may be fine. If you just treat any reading less the 90 volts as zero volts you should be fine with any digital.
 
  #7  
Old 07-07-12, 05:16 AM
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ray2047, you were right about the digital multimeter being influenced by induced voltage. watched numbers go up and down even before using the probes!

got readings of around 180v for #1 receptacle and around 70-80v for the latter three receptacles. After I shut off the power, found wire connections were fine for #2, 3, and 4. The problem was in #1 with a burnt silver terminal. Black wires hooked up to the silver screws and white wires on the brass screws. Black is definitely the hot wire. Wondering how I did this stupid and dangerous move! probably because I saw the old receptacle was upside down (ground on top, slots below) and wired it without switching wire positions. silver screws were a dull finish that apparently looked close enough to the brass in color. DUH!!

replaced receptacle and wired it correctly for a middle-of-the-run outlet: black wires on brass screws, white wires on silver screws, ground wires connected with wire nut and attached to ground screw on metal box. restored power and all outlets reading around 130v. Plugged everything back in. no problems. I'm tossing that cheap voltage detector and getting the analog multitester. I'll also be paying closer attention to what I'm working with. Thanks for your help!
 
  #8  
Old 07-07-12, 05:40 AM
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The ground should also be connected to the receptacles.
 
  #9  
Old 07-07-12, 05:58 AM
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Progress!
probably because I saw the old receptacle was upside down (ground on top, slots below) and wired it without switching wire positions.
There is no top or bottom, they can go either way. Please follow PCBoss' instructions. You must run a pigtail to the ground screw.
 
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Old 07-07-12, 08:48 AM
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ground wires connected with wire nut and attached to ground screw on metal box.
That sounds fine. You could add a pigtail to the ground wires to connect to the ground screw on the receptacle if you want to, but it's a belt-and-suspenders add-on when you're mounting the device in a metal box that's bonded to ground.
 
  #11  
Old 07-07-12, 09:18 AM
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From the 2011 NEC Article 406.4.

(B) To Be Grounded.
Receptacles and cord connectorsthat have equipment grounding conductor contacts shallhave those contacts connected to an equipment groundingconductor.
Exception No. 1: Receptacles mounted on portable andvehicle-mounted generators in accordance with 250.34.Exception No. 2: Replacement receptacles as permitted by406.4(D).
(C) Methods of Grounding.
The equipment grounding conductorcontacts of receptacles and cord connectors shall begrounded by connection to the equipment grounding conductor
of the circuit supplying the receptacle or cord connector.
 
  #12  
Old 07-07-12, 04:47 PM
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PC, are you saying that (new for 2011?) the EGC must be connected to the grounding contact of any receptacle (but not any switch) even when that receptacle is mounted in a bonded metal box?
 
  #13  
Old 07-07-12, 07:23 PM
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Unless the OP has a metal box that is installed to meet the requirements of 250.146, he/she must use the EGC. Personally, If one is there, why not use it. This goes back to what we talked about when it comes to using approved conduit as an EGC. Why rely on the conduit!! Just my .00001.
 
  #14  
Old 07-07-12, 08:53 PM
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Unless the OP has a metal box that is installed to meet the requirements of 250.146, he/she must use the EGC.
OK. What are the requirements of 250.146?

Personally, If one is there, why not use it.
I do it often. I'm just asking about the specific nature of the requirement.
 
  #15  
Old 07-07-12, 09:54 PM
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@ Nash,
if you have a code book (2008 or 2011), then you already know, so I’m not going to type or past it.
Are you trying to get me to type a book…………..LOL!!! Joking
I’m in a good mood—which is rare!!
 
  #16  
Old 07-08-12, 06:51 AM
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Some receptacles are U.L. Listed as self grounding when used in a metal box that is properly bonded to ground, but most residential grade receptacles are not. It used to be common practice (35+ years ago) in residential work to not attach a ground wire to each receptacle when installing in grounded metal boxes, but that practice has changed along with the use of plastic boxes. It's pretty rare to find metal boxes in new residential construction any more. Here is one that is self grounding.

Leviton® Industrial Self Grounding Receptacle, Ivory, 5262-SI - Crescent Electric Supply Company
 
  #17  
Old 07-08-12, 10:53 AM
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@ Casual,
250.146 mentions them. Or are you just adding more of what has already been added?
Fact: The section pretty much agrees with Nash and PC. That’s why I posted it.
 
  #18  
Old 07-08-12, 02:06 PM
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@ Casual,
250.146 mentions them. Or are you just adding more of what has already been added?
Fact: The section pretty much agrees with Nash and PC. That’s why I posted it.
Just supplemental information since you referenced it and didn't post it. Not everyone who reads this forum has a code book and most likely, very few DIYers do.
 
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