I came across a house yesterday that had no ground rod, just the grounding conductor hanging from the house. The house was about 3 years old and was occupied. Hmm, didn’t think the power company would put in a meter without a grounding rod.
I looked around the garage (where the panel was located) for a box where a UFER connection might be but found nothing. Exposed plumbing didn’t have any bonding either. So I am thinking the system is not grounded. FWIW, the electric service was provided via buried laterals.
Since there was no visible means of grounding, I called it out for an electrician.
For grins and giggles I whipped out my Sure Test, it indicated “Wiring OK”.
Now I am wondering was the Sure Test wrong? I would think that it would have indicated a “No Ground” condition or is it not that smart?
All the suretest, or any other plug in tester, will tell you is that the equipment grounding conductor is bonded to the neutral.
It really takes a lightning strike nearby to test the ground electrode conductor connectoin and surge protector bonding. The impedance there is the square root of the number of electrical devices destroyed.
A ground rod is usually a supplemental grounding electrode. The system should either be connected to the incoming metal water piping (within 5’ of the entrance to the house) or connected to building steel (if present and effectively grounded) or foundation steel (rebar, connected by approved methods). A ground rod by itself is usually not an effective grounding method.
James,
Is this a state thing / local thing where you are at?
What does" effectively grounded" for a wood frame house mean?
A ufer ground?
"Water pipe must be supplemented (not sole electrode) IRC 3508.1.1
NEC 250-50C (from code check)
I work in the Chicago area where a cold water pipe is used without a Grounding Electrode in old buildings BUT here lies the problem. Water pipes corrode at especially at fittings plus many old buildings used soft lead water pipes. A poor grounding electrode if you ask me.
I would argue that a grounding electrode IS an effective grounding method. But I will defer to the board sparkies for futher comment.
Sure Test is not pcycic - draw out a schematic and you will see how Sure Test can be fooled – As you can see the house ground is just a figure of speech electrically. Remember that the neutral and the “ground” are bonded at some point. Normally at the main breaker panel.
Many of the power company techs will recommend a 2nd rod that is located at least 5 feet from the foundation. This is usually after a nearby lightning strike that trips most of the breakers in the panel. The magnetic fields produced by the strike will still trip breakers with one rod that may be in fairly loose soil. I often recommend a 2nd rod on homes that are waterfront due to the frequent lighting there.
Hey Brother…since that nice old grounding electrode is only 25 ohms or less to ground…chances are it is not greatly effective as it pertains to the house voltage…really only their for trans and lightning issues…since as you stated at the main panel disconnect they are bonded together anyway with the grounded conductor back to the Trans…so this is why the SureTest will still give a reading…without the rod connection.
On a related note…I guess…lol
This is why many are electrocuted at pole lights to parking lots in some cities…they run a grounding electrode down to a ground rod thinking that meets the NEC…and it does in terms of technicals…However it is not safe because a poor 25 ohms cant aid in clearing a fault if is becomes a issue and well…death happens.
Do the math…120V and 25 OHMS resistance…only 4.8 amps draw…sure is not going to trip anything…so it can’t clear the fault…you touch…you become a path and well…get smoked…
Does a Service Panel need bonding to a ground rod?
I see a lot of Service Panels not bonded to the meter box because plastic conduit attaches the two panels without a bond wire. Only a service ground available?
The NEC says the service can be attached to the GEC at the Meter, Panel or actually the Messenger wire…kinda depends on the AHJ and POCO in the area…as in my area we have one county that likes the GEC into the Panel and the other county likes it into the Meter Can…go figure.
Yes, if you are using a supplimental ground rod it needs to be connected…but it will not stop the function of the system if it is not…just you will have no protection from Trans Volt or Lightning Issues.
Now if the Ground Rod is the ONLY source of the GE…it still would need to be connected.
In older homes you may only see a waterpipe connection…I still always suggest a supplimental when I do these inspections…kinda the more is better approach.
All,
Sorry for getting back to this so late. Fortunately I have been busy. I had a feeling the SureTest was giving the OK due to the bonding back at the panel, just wanted to be sure.
Thanks for all the replies, especially the technical aspects provided by our electrician friends.
The sure test only measures the resistance between the the neutral and ground pins in the receptacle. It has no way of seeing the ground electrode. It is a little better but I am really not sure it is 50 times better than a five buck 3 light tester.
I think the only issue other than makes the Suretest better is the fact the 3 light tester is useless on bootleg grounds and it does not give us additional readings for those who may do enhanced inspections.
