Power Supply Indicating Poor Ground on GFCI Outlet

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  #1  
Old 09-21-13, 07:27 PM
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Power Supply Indicating Poor Ground on GFCI Outlet

I recently moved into an apartment that only had 2 prong outlets. My landlord was kind enough to get someone to run a ground wire to the breaker box and install 2 GCFI outlets in my room so that I could use some of my more sensitive electronics (Desktop gaming PC, TV, etc.)

Yesterday, I came home from class to find that all the work had been done. I eagerly plugged a generic surge protector into one of the outlets and it indicated an ungrounded outlet (or poorly grounded, I guess). Using a GCFI outlet tester, I verified that the wiring is all correct (no switched hot/neutral, etc.).

Does this mean that my ground is of poor quality, despite the proper wiring, or is the indicator on the surge protector an unreliable source for making that call?
 
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Old 09-21-13, 07:33 PM
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Welcome to the forums.

I've run into that before with surge protectors. Their protection devices are referenced to ground. It sounds like you have two GFI receptacles with no ground. You are protected from ground faults but your equipment will not be protected from surges.

If I didn't know any better..... I'd say they didn't run the grounds.
 
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Old 09-21-13, 07:37 PM
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Thanks for the quick reply.

My problem with that explanation is that I can see the ground wire. They ran it out the basement (where the breaker box is) up the side of the house into my room along the wall to the outlet. I could go check to see that it is going into the breaker box, but I seriously doubt they would take the time to run the wire and not hook it up properly (whatever that entails; new to electricity here).
 
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Old 09-21-13, 07:56 PM
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Ultimately you may need a meter to check for the ground at the receptacle.
 
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Old 09-21-13, 08:01 PM
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From what I've read, the outlet tester requires a ground to trip the GFCI when testing the ground fault functionality, so there is a ground present (the tester can trip my outlet). I guess what I'm asking is how to determine the quality of the ground, since my surge protector seems to think it isn't good enough.
 
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Old 09-21-13, 09:43 PM
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As I previously stated.....you will need a voltmeter to check the ground.
 
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Old 09-22-13, 03:54 AM
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I know you said you trust them to have run the ground to the breaker panel, or why would they go to so much trouble. Have you followed the wire to the breaker panel to ensure it goes inside? I know it is a rental, but knowing what they did may ease your mind. Don't touch anything in the panel since it is not yours, but satisfy yourself that they did what they were supposed to do. For all you know, they clamped the grounding wire to a water pipe or to some other metal member of the house, which would give you an inferior ground.

BTW, a GFCI doesn't need a ground to trip. It uses the differential between the hot and neutral and when that differential crosses a certain threshold, it trips. If one is installed without a ground it will still operate as a GFCI, but must be remarked on the cover that it has no equipment ground. It would be interesting to see what you find out.
 
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Old 09-22-13, 06:23 AM
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The new ground wire (equipment grounding conductor) run where you could see it is legitimate provided that the ends are connected to the correct places. Since you can see it, that makes it a little easier to see that it is correctly run.

Normally the lower end is connected to the ground bus bar (terminal strip with EGCs of other circuits connected) in a panel.

The lower end may be connected (clamped) to a metal cold water pipe within 5' of where it exits the house undeground provided that there is also a fat ground wire (a grounding electrode conductor) connected to the same pipe and going to the main panel (with the master breaker or switch for the building) neutral bus bar.

The lower end may end at the aforementioned GEC if it reached that before reaching to the panel.

The upper end would be connected to the green ground screw of the receptacle. It may be daisy chained or pigtailed to other receptacles on the same branch circuit.
 

Last edited by AllanJ; 09-22-13 at 06:53 AM.
  #9  
Old 09-23-13, 09:53 AM
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Situation Update

So I started tracing the ground wire and found the end wrapped around a bolt (after some research, this seems to be a bolted clamp, probably installed by Comcast) on the outdoor water hose hookup (and not to the breaker box!). I am aware that this is a fairly standard thing, using the pipes as a ground. Also, the nearby comcast box has a ground wire wrapped around the same bolt.

I'm not sure if the pipe is simply not a good ground or if the comcast also being grounded at the same place is impeding the grounding ability of the pipe. There's also the possibility of plastic fittings somewhere in the line, from what I've read.

I guess I could always get a rod and make my own ground now that I have a ground wire run from the outlet. Still, I would like to know why the pipe isn't grounding properly and if there are other options. There's also the issue of the comcast wire, which is possibly not properly grounded. I'm not sure of the consequences of that either.
 

Last edited by Jargan; 09-23-13 at 10:45 AM.
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Old 09-23-13, 11:04 AM
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I guess I could always get a rod and make my own ground
No, that is not code compliant. The ground wire must go to the panel or be connected to an acceptable ground such as a ground rod or metal pipe connected by a ground wire to the panel and said connection must be within five feet of the panel.

Explanation: There are two type of grounds. Ground rods are to bleed off atmospheric charges (caled GEC). Ground wires from device to panel are to clear faults by tripping the breaker (called EGC). A conductor to the panel is necessary to insure a low resistance path. A ground rod may not provide a low resistance path.
 
  #11  
Old 09-23-13, 11:42 AM
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In that case, is my only option to run a new wire from the outlet to the panel? Can I extend the current wire or do I need to replace it entirely?
 
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Old 09-23-13, 12:39 PM
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In that case, is my only option to run a new wire from the outlet to the panel?
Yes*, or within five feet as explained in my preceding post.
Can I extend the current wire or do I need to replace it entirely?
Replacing is the best option.

*As a tenant for liability reasons you shouldn't do any electrical work. Call your landlord.
 
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Old 09-23-13, 04:05 PM
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Originally Posted by chandler
BTW, a GFCI doesn't need a ground to trip. It uses the differential between the hot and neutral and when that differential crosses a certain threshold, it trips.
Absolutely correct.

From what I've read, the outlet tester requires a ground to trip the GFCI when testing the ground fault functionality, so there is a ground present (the tester can trip my outlet).
Also absolutely correct!

Lacking any other handy and reliable way to cause the GFCI to sense more power "going out" on the hot wire than it senses "coming back" on the neutral, a plug-in GFCI tester shunts power to ground. No ground, no shunt, no test.

I guess what I'm asking is how to determine the quality of the ground, since my surge protector seems to think it isn't good enough.
Probably only doable with a megger. You don't own one of those and don't want to have to buy one (hundreds of $$$). Trust the ground. BTW, GFCI isn't necessary unless they only ran the ground to one location and then used a GFCI to allow them to legally install standard 3-slot receptacles on ungrounded wiring downstream - but that would defeat the purpose of the work - having the ground for the electronics.

I'd plug in and move on. A UPS wouldn't be a bad investment here if you don't already have one.
 
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Old 09-23-13, 05:00 PM
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A non megger way to get a rough idea of the quality of a ground is to use a pigtail light socket with a 60 watt bulb to test for power between hot and ground. If the bulb appears to be at about full brightness you probably have a usable ground... no guarantee.
 
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Old 09-23-13, 06:10 PM
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I'd plug in and move on.
I appreciate the advice and just want to clarify the entire situation here. I have a ground wire running from the outlet to an outdoor water pipe coming from the basement (the water hose hook up). There is also a cable line grounded to this same pipe, so I assume when Comcast hooked that up they had the same idea (this will do and is much easier than running the wire around the house and into the basement to the panel).

My surge protector is indicating a poor ground, but I'm not sure how high the standards of this measurement are. The outlet tester I have does indicate the presence of a ground, so that's something.

I am inclined to go ahead and plug it in because there is a GCFI to protect me, at least some level of grounding for the outlet (to the cold water pipe), and a surge protector between the outlet and my electronics. Still, I am terrified of losing my desktop PC and other sensitive electronics, and being less than aware of the proper precautions and risks involved, I am even more afraid of something happening.

So, here's my question: I have a potentially poor ground. What are the consequences of running sensitive equipment (gaming PC, LCD TV, etc.) on this ground over time? Is just having a ground present, no matter the quality, going to prevent most problems short of a lightning strike?

(Forgive me if I am being overly cautious. I do not feel comfortable further pressuring my landlady if the solution her guy provided was a reasonable one, but I also want to protect my stuff).
 
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Old 09-23-13, 06:23 PM
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I guess what I'm asking is how to determine the quality of the ground, since my surge protector seems to think it isn't good enough.
Your surge protecter is telling you it's not good.

Your landlady has provided a less than acceptable solution to the problem.
 
  #17  
Old 09-23-13, 07:02 PM
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Okay to run a jumper from the lower end of the ground wire the landlady had run, over to a panel or to a grounding electrode conductor. You might be able to do this with nobody looking.

Just wrapping a wire around a bolt does not necessarily make a good connection even at that point.
 
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Old 09-23-13, 07:21 PM
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so I assume when Comcast hooked that up they had the same idea (this will do and is much easier than running the wire around the house and into the basement to the panel).l
We have had posts here before regarding totally unacceptable grounds by the cable company so I'd take what they did with a grain of salt.

The outlet tester I have does indicate the presence of a ground, so that's something.
Outlet testers often give false results under some circumstances. An analog multimeter is the way to do an accurate test.
 
  #19  
Old 09-24-13, 02:33 PM
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I started tracing the ground wire and found the end wrapped around a bolt (after some research, this seems to be a bolted clamp, probably installed by Comcast) on the outdoor water hose hookup (and not to the breaker box!).
Oops! Missed this before.

Originally Posted by chandler
I know you said you trust them to have run the ground to the breaker panel, or why would they go to so much trouble. Have you followed the wire to the breaker panel to ensure it goes inside? I know it is a rental, but... satisfy yourself that they did what they were supposed to do. For all you know, they clamped the grounding wire to a water pipe or to some other metal member of the house, which would give you an inferior ground.
I am aware that this is a fairly standard thing, using the pipes as a ground. I'm not sure if the pipe is simply not a good ground or if the comcast also being grounded at the same place is impeding the grounding ability of the pipe. There's also the possibility of plastic fittings somewhere in the line, from what I've read.
The cold water inlet (incoming water supply pipe) is the first and best path to ground accepted for creating a grounding electrode conductor - a GEC, the bond that establishes the low-impedance path to ground and, at the same time, protects the electrical system from high-voltage transients (i.e., lightening) from outside.

That said, the inlet pipe must metal, must extend at least 10' outside, and must be bonded within 5' of entering (inside) the structure or before the first fitting, whichever is less. An added EGC (branch circuit grounding wire) may be terminated to the ground bus inside the panel where the circuit to be protected originates or to a bonding jumper that is part of the GEC, within 5' of the panel.

I guess I could always get a rod and make my own ground now that I have a ground wire run from the outlet. Still, I would like to know why the pipe isn't grounding properly and if there are other options.
Originally Posted by PJmax
Your landlady has provided a less than acceptable solution to the problem.
They didn't even bond it to the pipe when they got there! Ask to have it redone, properly.

I am inclined to go ahead and plug it in because there is a GCFI to protect me,
The GFCI, as said earlier, doesn't provide any useful protection in that location.
at least some level of grounding for the outlet (to the cold water pipe),
Inadequate.
I do not feel comfortable further pressuring my landlady if the solution her guy provided was a reasonable one,
Understood. It was far from reasonable or adequate.
 
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