Open Ground Receptacle (Don't Do This)

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  #1  
Old 02-28-16, 08:31 AM
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Open Ground Receptacle (Don't Do This)

I was replacing a receptacle and was not able to figure out for hours why there was an open ground on the tester. I had to get new receptacles and when installed, it showed correct on the tester. Once mounted back into the wall, it showed open ground again.


Turns out, the ground prong on the tester receded back and forth.

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Old 02-28-16, 09:02 AM
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We always recommend an analog multimeter for best testing. Plug in testers are good for a quick test but can be misleading.
 
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Old 02-28-16, 08:27 PM
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Any tutorial for the weekend warriors on how to use an analog multi meter for receptacle? The last thing I want to do is to stick two probes into the receptacle and have my hair raised.
 
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Old 02-28-16, 08:55 PM
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You won't raise your hair. The probes are insulated except for the metal tips. Just keep your finger from the metal part and you will be fine.
  • Wide slot to narrow slot should be 120v 10%.
  • Wide slot to ground should be less than 5 volts.
  • Narrow slot to ground should be 120v 10%.

Sometime you have to wiggle the probes a bit to get good contact.
 
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Old 02-28-16, 09:09 PM
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Thank you Ray. You brought confidence to me. I will give it a try tomorrow and take one for the team.

I remember when my brother and I installed an indoor motion detector. When we turned on the breaker, a huge buzz noise and then a zap. I was so scared. Luckily, it tripped the breakers.
 
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Old 02-28-16, 09:22 PM
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You haven't herd a zap till you have seen a dead short on a 480v fused for 100 amps. Cover on the controller box went nearly 20 feet.
 
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Old 02-28-16, 09:23 PM
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ray. Why do you recommend an analog multimeter over a digital multimeter?
From what I have experienced an analog multimeter is good for measuring fast changing voltage or load, but a digital was better in most other applications.
Analog multimeter is also easier to break. When dropped, it may damage caliprated spring on the gauge. I broek 2 that way.
 
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Old 02-28-16, 09:38 PM
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When I became a home owner 15 years ago, I did not know the difference between Hot or Neutral wires. I also did not know the difference between Line and Load. When we bought the indoor motion detector, it comes with a Line and Load. We connected the Line to the Hot and the Load to the Neutral. That caused the obnoxious ZAPPING noise. I am sure your situation was much more dangerous.

Thank you Ray! Have a good night.
 
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Old 02-28-16, 10:37 PM
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We normally are talking about residential AC voltages here and our recommendation applies to those uses. There are digital meters that have special circuits designed for AC but they are in the $100+ range. A pro or experienced DIYer knows when a reading is likely false due to induced voltage but a newbie may be confused by spurious readings.
http://support.fluke.com/find-sales/...105317_A_w.pdf

Also the analog multimeter has no battery (except for resistance readings) to go dead if the meter sets unused for a few months or couple of years (especially if accidentally left in the on position).
 

Last edited by ray2047; 02-29-16 at 08:59 AM.
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Old 02-29-16, 03:12 AM
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I agree with Ray. A person not accustomed to digital meters will just sit there looking at the 38 volts showing on the meter thinking they have voltage, when in reality it is Phantom voltage. It just makes diagnostics a little more difficult. The analog meter won't move until the prescribed voltage is applied.

The only thing I disagree with Ray on is the use of non contact testers. They have their place, just not in all instances. I scan a junction box after I kill the power to the circuit just to make sure I have gotten the right one. I do remodeling for a living. You wouldn't believe the number of circuits people can cram in a jbox. Kill one, but it doesn't get them all you are in trouble. Scaning the box for the presence of voltage just makes sense to me. Finding a particular wire that is hot, now that is a different animal. Too much induced voltage on a live circuit to do that accurately.

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Old 02-29-16, 07:03 AM
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Never thought about those induced voltages. I just ignore voltage that don't make sense.
 
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Old 02-29-16, 09:07 AM
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I just ignore voltage that don't make sense.
Yes, and for you I wouldn't suggest an analog. You know what you are doing.

The same goes for non contact meter. They can be useful if you understand their limitations and when to use them. Any test equipment suggested is aimed at beginners. We had a long thread that we just couldn't resolve because the wires the poster thought were hot weren't. The poster was using a non contact tester.
 
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