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Educate me on grounding: tester says "open ground" again, grrrrr

Educate me on grounding: tester says "open ground" again, grrrrr

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  #1  
Old 02-18-12, 03:48 AM
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Educate me on grounding: tester says "open ground" again, grrrrr

Question

If you put a pig tail ground on an outlet or switch it CANNOT SAY "open ground" on a tester? There are no grounds on any of my home outlets or switches (that I know of) because the ground is via the conduit in this whole place.

Background

I live in DuPage County, IL
Own this condo (1 building split into 4 owners)
Built about 1970
Grounding via conduit run throughout so none of the outlets/switches have ground tails

Problem

"Open Ground" happened on my tester again today. I was switching out the only outlet in the garage and the tester said "open ground." I was pissed so kept trying different things.

I put pig tail grounds on the light switch and outlet thinking how can this be? I HAVE PUT A GROUND ON so even if the conduit somehow ungrounded it iIS grounded. After 3-4 hours I stopped for the night.

My entire living space is above my garage and the 3 neighbors. I came upstairs and checked the outlet directly above (10' up) the one in the garage and the one 10' up in my living room said "open ground." So I'm too tired to mess with it.

My PLAN is to get a pig tail and put in the outlet. Then I'll go mess with the one outlet in the garage. Also, if pigtails will eliminate any "open ground" reading if a screw in the outlet box is loose or whatnot...I'll go buy like 20 pig tails and put them on every darn outlet and switch in this place. I'm losing hair on stupid stuff happening in my home!
 
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  #2  
Old 02-18-12, 04:03 AM
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It would be best to use a pigtail ground in every box unless you use self grounding fixtures. Also there is a possibility corrosion or mechanical damage to the conduit has degraded interrupted the ground. Adding a ground wire to the conduit would be the only sure way.
 
  #3  
Old 02-18-12, 04:29 AM
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IF you do not have a pigtail going to the box, and the receptacle is not attached to the metal box, it will show open ground.

However, if you do have a pigtail from the metal box and the device, it should show "correct" no matter what. If it does not, then you have another issue.

I also recommend using self grounding receptacles. Switches, attached to a metal box, are not required to have a grounding pigtail attached to it.
 
  #4  
Old 02-18-12, 06:39 AM
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I think we previously discussed this in another thread, but I don't recall if you were just testing with an outlet tester or a meter. Do you have a meter? I have never liked the outlet testers and feel that under some circumstances they can be misleading. I'd use a good multi-meter to check the hot wire to the box at the suspect outlet and see if you get a 120 volt reading.
 
  #5  
Old 02-18-12, 06:42 AM
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Grounding by Conduit

When a wiring system is grounded by the conduit, the conduit must provide a complete electrical path from each fixture all the way back to the service panel. Any break in the conduit connections or corroded conduit connections will cause the "open ground". Using a pigtail from the box to the fixture will only ground the fixture if the box is properly grounded through the conduit.

I would begin testing near the service panel and work my way out to the fixtures away from the panel. When the condition changes from "grounded" to "ungrounded", you have located the bad conduit connection. Just my 2 cents. Good luck with your project.
 

Last edited by Wirepuller38; 02-18-12 at 08:07 AM.
  #6  
Old 02-18-12, 07:14 AM
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I still think you need to do some testing with a meter before proceeding, but something to think about is the integrity of the conduit connection at the main service panel. If the panel box (loadcenter) is painted, as most are, you may not have a good bond from the box to the conduit as the locknut has to bite through the paint. A bonding bushing at the panel box would resolve that problem and allow you to effectively ground the conduit.
 
  #7  
Old 02-19-12, 04:08 AM
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I was pretty sad yesterday. It's like I was running a marathon, was in mile 23 and BAM...failure and did not finish the race. I had all my diagrams drawn, wires labeled, pictures taken, ready to put my new GFCI in (another story -- box too shallow and not wide enough).

Now to reply to posts since my last one....

Yes Joe, we did discuss this in a previous thread. Yes now I have purchased a cheapo $10 digital multi meter at Menards. I've only used it to test voltage. I've tested most outlets in my home and I typically get about 122 to 126 volts. I have a power conditioner that shows volts when you plug it in and it mirrors those "high" voltage readings.

And the "open ground" outlets also have voltage and all test today at 123 but that changes depending on the time of day tested.

Wirepuller38, you said "When a wiring system is grounded by the conduit, the conduit must provide a complete electrical path from each fixture all the way back to the service panel. Any break in the conduit connections or corroded conduit connections will cause the "open ground". Using a pigtail from the box to the fixture will only ground the fixture if the box is properly grounded through the conduit.

I would begin testing near the service panel and work my way out to the fixtures away from the panel. When the condition changes from "grounded" to "ungrounded", you have located the bad conduit connection. Just my 2 cents. Good luck with your project."

I have thought about this for awhile. I've tested all outlets on that circuit via hand held circuit tester. ALL outlets test CORRECT except the two lined up vertically 1 story from one another. The ones I'm having a problem with.

The breaker box is in kitchen. If I go in attic I believe the conduit goes in a 45 degree angle to an exterior wall. It goes down the wall to the outlet. That one is "open ground." From there it feeds down a story directly down to the garage only outlet where it reads, as we'd guess, "open ground" cuz it feeds it.

So my guess is the break is between my outlet in house above garage and breaker box. How the heck do I figure out WHERE the break is in that run? Can I send some sort of signal or tester?

Joe, the breaker box is still factory gray from 40 years ago. No owner applied paint. Further, breaker #4 is quite loose in the box. But since every other outlet on that circuit tests "correct" I have not messed with the breaker. Would the wiggly breaker cause just one spoke of a circuit to be open ground?
 
  #8  
Old 02-19-12, 06:47 AM
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Would the wiggly breaker cause just one spoke of a circuit to be open ground?
No, the breaker has nothing to do with the integrity of the ground.

Yes Joe, we did discuss this in a previous thread. Yes now I have purchased a cheapo $10 digital multi meter at Menards. I've only used it to test voltage. I've tested most outlets in my home and I typically get about 122 to 126 volts.
And, when you tested the voltage, did you test hot to neutral or hot to the box or both? If you test hot to the box and got the same voltage reading as when testing to neutral, you have a grounded box.

Joe, the breaker box is still factory gray from 40 years ago. No owner applied paint.
I only mentioned this because even factory paint keeps some conduit connectors from picking up a ground from the box. That and concentric knockouts are just a couple reasons why many engineers specify grounding conductors to be pulled with circuit conductors. I can't remember the last set of plans that allowed only a conduit ground and didn't specify a grounding conductor be pulled in.

If you still feel you have no ground or an intermittent ground, you could pull in ground wires from the last solidly grounded outlet and then ground the last 2 boxes and receptacles.
 
  #9  
Old 02-20-12, 06:24 AM
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Conduit Grounding

Sounds to me like you have isolated the problem. Now you have to verify the integrity of the conduit connections in that area or do as Joe said and install a ground wire in the conduit from the last correctly grounded receptacle to the ungrounded one. Are the conduit joints accessable?
 
  #10  
Old 02-20-12, 07:00 AM
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We occasionally have this problem in our workplace and will work at pulling an insulated green ground wire from the panel to the first box and then as far as we are able to.
 
  #11  
Old 02-21-12, 02:37 AM
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I'm a really mellow dude in life. I rarely get really angry or blow up. But this still makes me internally mad! So I had open ground on the two outlets. I woke up to go out to my family gathering and decided to test each outlet again before I left. OMG...each said "correct!" HOW can this be? Before I went to bed both said "open circuit."

It gets better. I get home from family thing and go to bed. Woke up this morning and test each outlet and "open ground" again. I did NOTHING to either outlet. Not flipped breakers. The ONLY thing I have done is put the outlet tester in each outlet. That's it. And it has flip flopped from open to correct to open. This is NOT right, uggggggggg.

Anyone want to guess what ghost is messing with me? Okay, let's get to it. I can't take it anymore. This is slowing down my life and I'm not letting the ghost win anymore. It's my house and it WILL say "correct" if I have to run a spool of wire around the block three times.
__________________________________________

What gauge wire do I need?
Stranded or solid?
Green or bare?

It's about a 50' run from the breaker box, through the living room outlet straight down to the first floor garage outlet (end of the lind). What do 50' lengths typically cost?

The breaker box is on the 2nd floor. I have access to my attic where the conduit runs at an angle on the attic floor to the outside wall, down the wall to the outlet on the 2nd floor, then straight down to the first floor garage outlet.

Any tips on securing the ground wire?
Any tips on running this through conduit? I've never done it before but have some 100' wire snake in a closet somewhere.
__________________________________________

My brother said not to even worry about an open ground. In his house he has had some for a decade and. What is the DANGER in having an open ground? What does that mean specifically?

Where do I put the ground wire in this box?

 
  #12  
Old 02-21-12, 05:46 AM
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Box Connections

Back off a bit and show us another photo of the entire box.
 
  #13  
Old 02-21-12, 09:59 AM
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Did you install grounding pigtails on the receptacle grounding lug and to the metal box?

(image courtesy of Ace Hardware)

There are several different types, both stranded and solid wire, with and without lugs. If you do NOT have the pigtails installed the mere act of plugging and unplugging can affect the grounding.

Equipment grounding is primarily to cause the circuit breaker to trip on a "fault to ground". It is for safety. If you (your brother) never have a "line to ground fault" (short circuit) then the equipment grounding circuit will never be needed. do you want to take the chance? Are you feeling lucky?

The equipment ground circuit also plays a part in the operation of surge suppressors and some electronic devices.
 
  #14  
Old 02-24-12, 03:27 AM
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Yes, I installed those neato grounding pigtails in the "open ground" box a few days back and it did not help. I bought a few more today and I'll begin putting them in every outlet in my place...

wirepuller, I'll get you that full pic of the inside of my circuit box tomorrow.

Joe you said:

And, when you tested the voltage, did you test hot to neutral or hot to the box or both? If you test hot to the box and got the same voltage reading as when testing to neutral, you have a grounded box.

Okay, I tested the outlet and it still says OPEN GROUND so then tested all different ways with a $10 digital multimeter (they have a $40 one would that be better?). If you were to plug in a plug there is a fat blade, a skinny one, and a ground circle. I stuck the meter probes in the following and got these readings from the OPEN GROUND outlet:

Fat blade to skinny blade = 123.4 Volts
Fat blade to box = 23.5 V
Skinny blade to metal outlet box = 39.6 V
Fat blade to ground circle = 23.5 V
Ground circle to skinny blade = 40.3 V

Confused by getting any reading on some of those I decided to check a different outlet on a different circuit that tests CORRECT:

Fat blade to skinny blade = 122.6 volts
Fat blade to box = 0
Skinny blade to metal outlet box = 122.6
Fat blade to ground circle = 0
Ground circle to skinny blade = 122.8

I don't know electricity but it looks like something is very wrong. Can someone explain what is bad from the numbers above and what they mean?
 
  #15  
Old 02-24-12, 06:58 AM
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Your first set show a bad ground. The second set are correct.

Based on your second set of measurements your meter is working correctly.
 
  #16  
Old 02-24-12, 05:59 PM
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Skinny blade to metal outlet box = 39.6 V
That would be the hot to box which apparently is either not grounded or is more likely poorly grounded. This tells me you have either a corroded or loose conduit connection, probably at a conduit coupling. I would go back to the last solidly grounded box and pull in a green insulated grounding conductor from there and at each box, attach the ground wire to each box. The grounding pigtails you have already installed should properly ground each receptacle.
 
  #17  
Old 02-24-12, 06:36 PM
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There is a breakdown in the conduit somewhere. Could be a loose connection at a coupling or connector. Are the locknuts tight in the boxes?
 
  #18  
Old 03-04-12, 02:04 PM
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Belated, but below is a really good picture of the breaker box. And another odd thing happened. the circuit said "open ground" upstairs (the line that feeds the only outlet in my garage) and the one in the garage said the same. I plugged in a 12/3 25' extension cord and the circuit tester then said "correct."

I did not believe that lying tester so left it in the outlet. Unplugged extension cord and "open ground" occurred. Plugged in extension cord on the outlet again and said "correct." Now THAT is weird. Anyone know why that happened?

I did buy a 50' roll of 14g green solid wire for $10.50 at Menards just have not gotten to running it yet. God it is so darn dusty in the attic and insulation everwhere. One misstep and I fall through th e floor/living room ceiling and that would be a fun repair...



 
  #19  
Old 03-04-12, 02:52 PM
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I would suggest you stick to using an analog multimeter for testing.
 
  #20  
Old 03-04-12, 02:53 PM
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If this is a sub panel, which it appears to be, you ground wire should not be connected to the neutral bar.

The 2 blue #12 wires can not be double lugged on the main feeder lugs! They are greatly overfused!!! You need to install some tandem breakers.

It also appears to have clearance issues in front of your panel.

Now, on to your open ground issue: Have you replaced these receptacles? It sounds like it is only a poor connection in the device.
 
  #21  
Old 03-04-12, 04:33 PM
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I second what Tolyn states. Your ground cannot be grounded to the neutral bar if the picture is a sub panel. You must buy a grounding bar and correct this. I also would replace the recepticles
 
  #22  
Old 03-04-12, 06:06 PM
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Guys this is part 2 a long thread. It has been long established this is a subpanel and has at least three major violations.

Nibroc, you should perhaps put the minor issue of ground on the back burner and concentrate on correcting the major violations.

Pictures from his previous post at http://www.doityourself.com/forum/el...ml?highlight=:


 

Last edited by ray2047; 03-04-12 at 07:27 PM.
  #23  
Old 03-04-12, 10:34 PM
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"If this is a sub panel, which it appears to be, you ground wire should not be connected to the neutral bar. The 2 blue #12 wires can not be double lugged on the main feeder lugs! They are greatly overfused!!! You need to install some tandem breakers."


I know likely makes you cringe but could you explain double lugged, greatly overfused, and tandem breakers?

"I second what Tolyn states. Your ground cannot be grounded to the neutral bar if the picture is a sub panel. You must buy a grounding bar and correct this. I also would replace the recepticles"

Recepticles replaced since that is the easy stuff a guy like me can do. Since there are no ground wires in my whole house, where is the conduit "grounding" to? I assumed in that sub panel in my condo with all the breakers?

"I would suggest you stick to using an analog multimeter for testing."


Why is an analog multimeter better than digital for testing. It seems it would be hard to get an accurate number to write down when you get readings on analog?
 
  #24  
Old 03-04-12, 11:56 PM
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I know likely makes you cringe but could you explain double lugged, greatly overfused, and tandem breakers?
Double Lugged is two wires under a lug designed for only one wire. This refers to the two blue wires at the top of your panel. Such a connection may lead to a less then ideal connection with higher then normal resistance which in turn cause heating, perhaps to the point of failure.

Greatly over fused again refers to the blue wires. Because they are not on a breaker they are only protected by the breaker or fuses in the main panel outside. Because of their small size a short would not necessarily trip that breaker or fuse before they started a fire.

A tandem breaker is two breakers whose total size is the same as a single breaker in many panels. In a GE it is a separate breaker half the size of a regular breaker. It is used when you need to put more breakers in the panel then you can with full size breakers. The panel you have needs to be moved away from the water heater to meet code so when you put a replacement panel in you could just use a larger panel making the issue of tandem breakers moot.

Since there are no ground wires in my whole house, where is the conduit "grounding" to? I assumed in that sub panel in my condo with all the breakers?
No. It is grounding through conduit to the main panel outside. Under modern code for a subpanel the neutral bar must be isolated from the panel and a separate ground bar bonded to the box. However your subpanel is probably grandfathered.

Why is an analog multimeter better than digital for testing.
My mistake I though you were using a plug in tester. However in general for voltage testing it is better because it is less affected by induced voltages which can cause false readings.
 
  #25  
Old 03-05-12, 05:03 AM
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I wonder if the problem is that the subpanel may have the grounding issue.

Thanks for linking the two threads Ray, when I saw the blue wires in the lugs I suspected we had seen part of this before.
 
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