I checked the circuits with my circuit tester (yellow, 3 prong tester, nothing fancy), most of the receptacles showed correct wiring except a couple of them. When I inspected the service entrance panel I noticed there was no grounding rod buried in the ground.

Question:

Since there is no grounding rod, shouldn't the circuit tester read "open ground"?

Thanks a billion you all.

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Matt Kelekci
Houston TX

The ground you are most likely reading is from the power company neutral. The neutral is grounded at the transformer and is bonded at the service equipment.

James, thanks for the reply.
Just out of curiosity, why do we have grounding rods then?

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Matt Kelekci
Houston TX

www.theelectricalguru.com/GandB.pps

There are several grounding methods.

Did you not see a grounding conductor at the service equipment or in the panel?

Many times I do not see a grounding conductor attached to a ground rod. Those homes are either grounded to the steel in the foundation, a Ufer ground or to the plumbing.

The situation that James is talking about is only true at the service equipment. Once you go downstream of the service equipment the neutral and grounds should not be connected. (Neutrals and Grounds on their own bus bars, with no jumpers between them.) At this point the neutral is floating and will not have any impact on the ground readings at an outlet. Now if you have false grounds at the outlet this is a different story. The neutrals are then used to provide a "False" ground by jumping the ground and the neutral. This is how folks get 2 wire systems to show a ground, albeit a False Ground.

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Scott Patterson
Spring Hill, TN
http://www.traceinspections.com

What the other folks have said is dead on the mark. To elaborate on your question a bit more...if you have no other grounding electrode, (such as a ground rod, ground to the steel in the foundation, a Ufer ground or to the metal plumbing system) you will still have a grounded system as long as the neutral is grounded at the transformer. The power company normally uses a ground rod for their grounding electrode. This is what the bare copper wire you see run down the side on the pole attachs to.

The purpose of multiple or additional grounding electrodes (such as a ground rod) bonded together is to create a grounding electrode system that does not rely on a single point that could fail with no backup. As long as one of these grounding electrodes is intact you will have a grounded system...hopefully!

Thanks for the replies.

I didn't see any grounding electrode at the service equipment.
I guess electrons got only one path to ground which is power company's grounded wires.

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Matt Kelekci
Houston TX

If you have any metal plumbing, gas, or structural steel in the house it should be bonded to the power company's neutral. I provided only a answer to your question...not a answer to your potential problems. Be sure to check the electrical system very closely using your own knowledge.

We have grounding rods (and other methods of grounding to earth) to deal with lightning and other high voltage accidents and to help stabilize voltage in the event of something like a poor neutral connection. The grounding rods are not there as part of the equipment ground path - there is too much resistance in the path through the earth to cause overcurrent devices (breakers) to trip.

Someone correct me if I'm wrong (J.P.?), but if everything else is wired correctly, your tester would indicate a "grounded" receptacle outlet even if both the house grounding conductor and the transformer grounding conductor were cut. The tester is verifying continuity between the equipment ground terminal on the receptacle outlet and the service neutral. It doesn't tell you much, if anything, about the earth ground path.

You could very well be correct when using a basic plugin tester that does not need or use the earth ground for a reference point. The higher quality meters will note a missing earth ground I believe.

As stated above the electrodes are for keeping the house at the same potential as the earth.

The grounded conductor from the power company 'grounds' the system.

Pick up the NEC and read the definitions on all the different grounding and bonding terms. This may help you understand.

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Mike Parks
RBO ESI

Thank you all for great posts.

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Matt Kelekci
Houston TX

John,

It does not tell you anything about the earth ground path.

The circuits are only being tested back to the point where the neutral is bonded to ground, i.e., 'the service equipment'.

The service equipment does not even have to be grounded to earth at all for the circuits to test out as "grounded".

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Jerry Peck, Construction / Litigation Consultant
Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )

Jerry is correct. The three-prong plug-in tester will only verify that a circuit can be completed by sending current from the energized conductor to the ground conductor. If the grounding buss is properly bonded to the service equipment at the service entrance, then it will indicate that the circuit is grounded, even if there is no grounding electrode at the service entrance equipment. Golly, I hope I got my terminology correct there.

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Randy Aldering, RHI CHI
Housesmithe Home Inspection
www.housesmithe.com

Randy - Not sure if you meant to refer to the xmas-ornament type tester when you said "three-prong plug-in tester". James suggested that the more sophisticated circuit analyzers wouldn't be fooled, but that's not the case. The SureTest also doesn't tell you if a grounding electrode path is present, because that isn't the path it's testing.

I said a higher quality meter....I did not mention the Sure test...Fluke has a variety to chose from.....

James,

Not unless that meter is connected to earth ground itself. Of course, that would be a bit difficult to use going around the inside testing outlets with it.

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Jerry Peck, Construction / Litigation Consultant
Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )

Very true.....but it is a means to check the earth ground before you use a standard tester.

If you are going to do that, I would hope you would use a proper meter 'just for that' and then report the results, in ohms resistance, and then, if greater than 25 ohms is found and there is only one driven rods, you would need to report that as a defect and report that code requires a second driven rod (to clarify, I am using 'driven rod' to mean 'made electrode', it could be a rod, pipe, or plate) be installed a minimum of 6 feet from the first one.

Of course, checking resistance to earth ground is not a simple matter either, there is a precise method which needs to be used. Thus, I doubt any home inspector has the equipment or knows how to measure the resistance to earth properly.

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Jerry Peck, Construction / Litigation Consultant
Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )

Thank you for contacting us, but we don't have anything that will test
for ground at the receptacle.

Regards,
Fluke Technical Support