Plug in tester shows open ground

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alyoshak24

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Electrician
Hi guys, troubleshooting new construction garage and doing the trim and all outlets and gfi are showing open ground. This is in a garage with main panel not sub panel in garage because they brought service to garage.

Emt all throughout with electrical boxes so emt is being used as grounding system.

Have 3 balanced circuits as follows : A circuit dedicated to all lights, B circuit for car port, C circuit for miscellaneous room

Now the following is what I've done so far. (Used multimeter for all of it...

1. In panel I get 120v from either leg to neutral service conductor.

2. In panel I get 120v from either leg to neutral bus bar

3. In panel I get 50v from either leg to panel frame if I touch black lead tip to panel but if I angle black lead to edge of panel or in holes inside panel the. I get 120v (I didnt have to angle black lead when I touch bus bar or neutral leg)

4. Now outlet in Circuit A carport that has the panel in same room has 1 gfi with 4 other outlets downstream. That gfi is showing open ground but with the multimeter I show 120v from line contractor to EMT pipe. I even ran a ground wire from panel to outlet box and still showing open ground.

5. Even bought ground bar 4 slots and attached 3 grounds to them

6. Panel is grounded to meter via bushing and from meter we have it bonded to to 2 8ft ground rods 6ft apart (however that should not have any influence on a plug in testers reading.

7. Also in circuit A and B (carport / miscellaneous room) when I wiggled tester some outlets and gfis actually showed proper ground and i was able to reset and test gfi with plug in tester reset button...however it was intermittent because when i tried doing it over and over on the outlets and gfis that showed proper ground it then stopped and showed open ground again....again idky but my logic is that if line to pipe or box from a device then bonding is good and so is grounding....


Can you guys please help
 
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Is the main bonding jumper (usually a green screw through the neutral bar) installed?

Did you install grounding pigtails from the receptacles to their metal box, or did you use self grounding type?
 
alyoshak24 said:
3. In panel I get 50v from either leg to panel frame if I touch black lead tip to panel but if I angle black lead to edge of panel or in holes inside panel the. I get 120v (I didnt have to angle black lead when I touch bus bar or neutral leg)
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50v to the frame, but 120v to the edge of the panel or the holes in the panel???
I'm confused about what you are saying.

Are you saying 50v to the painted surface but 120v to where the bare metal is exposed such as screw holes or the sharp edges?
 
alyoshak24 said:
3. In panel I get 50v from either leg to panel frame if I touch black lead tip to panel but if I angle black lead to edge of panel or in holes inside panel the. I get 120v (I didnt have to angle black lead when I touch bus bar or neutral leg)
Click to expand...
This. The EMT can only serve as the EGC if it is continuous to the panel enclosure, AND the enclosure is bonded to the service neutral. Sounds like you're lacking the latter.
 
suemarkp said:
Is the main bonding jumper (usually a green screw through the neutral bar) installed?

Did you install grounding pigtails from the receptacles to their metal box, or did you use self grounding type?
Click to expand...
YES main bonding jumper / green big ass screw that bonds neutral bars to each other is installed, i even used my rough screw driver to give it more torque

I tried both methods, first original install was just attaching device to box since device came with self grounding gold/copper tab, then i tried tying ground cable from device green ground screw to box, then i tried running 14stranded ground cable from panel to device and still showing open ground....
 
Sea Nile said:
50v to the frame, but 120v to the edge of the panel or the holes in the panel???
I'm confused about what you are saying.

Are you saying 50v to the painted surface but 120v to where the bare metal is exposed such as screw holes or the sharp edges?
Click to expand...
sorry i should say that the tip of my lead only reads 50v give or take, but when i lay lead at an 50-75 degree angle to make more surface contact on my lead to the panel then i show proper 120v
 
LarryFine said:
This. The EMT can only serve as the EGC if it is continuous to the panel enclosure, AND the enclosure is bonded to the service neutral. Sounds like you're lacking the latter.
Click to expand...
would jumping the from the neutral to a ground bar in the panel fix this issue ?, also would the enclosure be bonded to the service neutral if the emt pipe is reading 120v from line from a device 8 ft away from panel thats piped from device box to panel ?
 
LarryFine said:
Yes, but this is theoretically already being done by the bonding screw that ties the enclosure to the neutral bus,
Click to expand...
so i tried this and in theory it shouldve worked but didnt....now i think my tester is bad. i cannot go into the clients home and ask him but i did try his outdoor outlets and received same reading...i am just going to HD to purchase a new tester and plugging it into that stores outlets to see the readings
 
I want to thank all you Masters and Sifu of the Electrical Trade for helping a peanut brained know it all.....im sorry i failed you guys.
 
Any time you life depends on a voltage test, you should use Live-Dead-Live (L-D-L) testing.
1. Try the tester on a known live source.
2. Test the subject circuit or equipment.
3. Try the tester on a known live source again.
 
I find these plug-in testers are okay when giving positive results, but they rarely correctly annunciate errors.
 
Barney B said:
Any time you life depends on a voltage test, you should use Live-Dead-Live (L-D-L) testing.
1. Try the tester on a known live source.
2. Test the subject circuit or equipment.
3. Try the tester on a known live source again.
Click to expand...
i have so far i believe, the description has every way i troubleshot thus far. maybe i skipped a step.
 
alyoshak24 said:
when I wiggled tester some outlets and gfis actually showed proper ground and i was able to reset and test gfi with plug in tester reset button...however it was intermittent because when i tried doing it over and over on the outlets and gfis that showed proper ground it then stopped and showed open ground again.
Click to expand...
Also, the only true test for a GFCI is the test button on the GFCI itself. Not the tester. I recently watched a Mike Holt video in which Mr. Holt stated as much. I'll try to find the video if you you're interested.
 
Sea Nile said:
Also, the only true test for a GFCI is the test button on the GFCI itself. Not the tester. I recently watched a Mike Holt video in which Mr. Holt stated as much. I'll try to find the video if you you're interested.
Click to expand...
It was in the new fundamentals/theory book/dvd. 24:30 minutes in to unit 26. The only proper way to test a GFCI is with the test button on the GFCI itself. It doesn't matter what the plug in tester does when you push the button on it. Edit: same for AFCI
 
Guys I went into HD and plugged my tester to 10 of their outlets and read open ground, opened a new plug in tester and they read proper connections on the same 10 outlets...am going to jobsite now and verifying that I was going Gary Busey crazy for no reason
 
Update guys I had a bunk gfi tester and confirmed with a new tester...the inspector insisted it showing wired correct via his plug in tester and didnt want to argue so all of these steps were right, readings right on meter and brain just got scrambled a bit. Thank you all for your help.
 
To add, the reason the test button on a plug-in tester doesn't work with no EGC is:

A GFCI device has access to both line conductors within the device, and mimics a shock by connecting a resistor to the hot wire after the sensor to the neutral ahead of the sensor.

A plug-in tester only has access to both line conductors after the sensor, so can only mimic a shock by connecting its internal test resistor between the hot wire and the circuit EGC.

For those dealing with (home) inspectors who use a plug-in tester: Use a grounding "cheater" and extend the green wire with an alligator clip on the other end, clipped to a ground.
 
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