3 Outlets Suddenly Malfunctioning

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  #1  
Old 08-28-13, 09:32 PM
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3 Outlets Suddenly Malfunctioning

Hello...need help...my first time to use forum. 3 outlets in my study suddenly began to malfunction last night. Using a Volt Meter set to VAC, 200V, with the Black Lead in the COM port and the Red Lead in the V port, I'm testing the switch and the outlets. For the switch, with Black Lead to Ground Wire and Red Lead to bottom screw (which has a black wire screwed to it), I get 120V. The top screw is empty of wire, but the switch has a black and a red wire both backstabbed in the rear. With the switch ON, I get 120.3V at both screws. With the switch OFF, I get 35.7V on the top screw and 120V on the bottom screw. Is this normal (i.e. 35.7V when the switch is OFF)?? Just checked the switched outlet and with the Black Lead to Ground and Red Lead to Smaller Hole, I get 120V when turned ON; however, it only drops to 18.5 V when switched OFF. Is this normal? When the switched outlet is still turned ON, I get 18.5V when testing the Black Lead to Ground and the Red Lead to the Larger Hole (i.e. neutral wire). Is this normal? Finally, with the Black Lead in the Larger Hole and the Red Lead in the Smaller Hole and the switch turned ON, I get 101V and when turned OFF, I get 21.4V. Is this normal??

These outlets have been working perfectly for the past 4 years since buying this 19-year old home. No breakers were tripped, and I've manually tripped and reset all breakers and still no cure.

Many thanks for any help on this.
 
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Old 08-28-13, 09:38 PM
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Welcome to the forums.

You said the receptacles are malfunctioning. Does that mean they are dead or work intermittently ?

Are you using a digital meter ?
 
  #3  
Old 08-28-13, 09:52 PM
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Welcome to the forums!

Using a Volt Meter set to VAC, 200V, with the Black Lead in the COM port and the Red Lead in the V port, I'm testing the switch and the outlets. For the switch, with Black Lead to Ground Wire and Red Lead to bottom screw (which has a black wire screwed to it), I get 120V. With the switch ON, I get 120.3V at both screws. With the switch OFF, I get 35.7V on the top screw and 120V on the bottom screw. Is this normal (i.e. 35.7V when the switch is OFF)??
It sounds like you're using a digital multimeter and reading induced voltage. Either ignore it or use an analog multimeter, which is less likely to pick that up.

The top screw is empty of wire, but the switch has a black and a red wire both backstabbed in the rear.
The two black wires should power in and power out to another load. They should be spliced together with a 6" to 8" black pigtail of the same gauge. That pigtail and the red wire should be connected to the two screw terminals. No wires should be inserted in the backstabs.

with the Black Lead in the Larger Hole and the Red Lead in the Smaller Hole and the switch turned ON, I get 101V
101V is not within the acceptable range of 108V to 132V for a 120V circuit. That reading, combined with the 120V you found at the switch, indicates a loose connection somewhere. All of the readings taken together indicate that it's probably in the ungrounded (hot) conductors.

If correcting the wiring at the switch doesn't solve the problem, post back and we'll go from there.
 
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Old 08-29-13, 05:34 AM
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Thanks, Nashkat1, I'll try rewiring and let you know.
 
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Old 08-29-13, 05:38 AM
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I should have been more clear on this point...they show voltage, but will not operate any lamps, etc..

I am using a 3-year old Craftsman digital multimeter that cost approx $30 on sale. It is a nice meter having a rubber case that resembles a Fluke. Am I learning from this forum that digital meters are unreliable for house wiring purposes?
 
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Old 08-29-13, 07:08 AM
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I should have been more clear on this point...they show voltage, but will not operate any lamps, etc..
The 101V hot-to-neutral reading made me suspect a drop in the feed voltage. This leads me back to suspecting an open or loose neutral.

Correct the wiring at the switch and check all terminations and splices, especially in the neutrals.

I am using a 3-year old Craftsman digital multimeter that cost approx $30 on sale. It is a nice meter having a rubber case that resembles a Fluke. Am I learning from this forum that digital meters are unreliable for house wiring purposes?
Digital multimeters aren't inherently unreliable. It's just that they don't always filter out induced voltage. The less expensive ones are especially prone to this. For roughly half of the cost of your digital multimeter you can get an analog one that shouldn't have that problem.

The 37.5V and 18.5V readings are almost certainly induced voltage. Those are what led both PJ and me to ask whether your test meter was digital.
 

Last edited by Nashkat1; 08-29-13 at 07:39 AM.
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Old 08-29-13, 07:35 AM
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The 101V hot-to-neutral reading made me suspect a drop in the feed voltage. This leads me back to suspecting an open or loose neutral.
With a 101V hot-to-neutral reading, if you get 120V hot-to-ground reading you definitely have a loose neutral connection. You'll probably find it at a backstabbed neutral connection on a receptacle.
 

Last edited by Nashkat1; 08-29-13 at 07:40 AM. Reason: Correct typo in my quote
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Old 08-29-13, 08:26 PM
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Thank you, Nashkat1, PJmax, and CasualJoe for responding! I moved all of the backstabbed connections to the screws on the sides. First at the switch and then the outlets...and kept testing to see who the culprit was. Turned out to be the third (and final) outlet. It was acting quirky, so I replaced it with a better outlet and now everything works perfectly again. So all of your help and guidance is very much appreciated.

I do have a new question though...when trying to figure out which breaker fed this circuit, I discovered that the overhead lights and the outlets in my Master Bedroom are on the same breaker. I thought these were supposed to be on separate circuits. Is this permitted under the Code? I live in VA.
 
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Old 08-29-13, 08:51 PM
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Glad you got it, and thanks for letting us know.

when trying to figure out which breaker fed this circuit, I discovered that the overhead lights and the outlets in my Master Bedroom are on the same breaker. Is this permitted under the Code?
Yep, legal as sunshine. I don't do it that way 'cause I like having more than one way to see when it gets dark, but a lot of folks do. Used to be the norm, way back in the day.
 
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