There are several types of grounding electrodes found in homes. At least one of these methods should be present in any home regardless of age, and newer homes usually require multiple methods----redundant methods.
Historically, the original method of achieving grounding was the water pipe coming from the street. The next method to be employed was a single ground rod. After this requirement, two rods driven 6 feet apart became the norm. Now a third method called a "Ufer Ground" is required in many jurisdictions. With this grounding method the entire rebar system of the concrete foundation is utilized. This method is far superior to all of the other methods, or even combination of methods in ensuring an effective ground.
One might ask, "Why so many different systems?" Well the main reason is that a lot of houses no longer have metal water pipes coming from the street. This leaves the ground-rod method as the only means of grounding and it is considered a notoriously poor means of grounding, so enter Mr. Ufer. While this method of grounding has been known since the 40's its employment as the primary means of grounding residential electrical systems has only recently been required in some jurisdictions.
One of the things I am interested in when inspecting the electrical system of a home is documenting what methods of grounding have been employed. It is surprising to me the number of homes I find where the water pipe from the street has been replaced with plastic pipe leaving the electrical system ungrounded at the home.
Without getting overly technical, this leaves metallic components of the electrical system vulnerable to being energized----creating a shock hazard. This picture was taken at a house with one ground rod, where the water line had been replaced with plastic. The loss of a grounding connection to the ground rod is pretty obvious.
Time to call the Licensed Electrical contractor for repairs.
Charles Buell
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Charles, I didn't know about this shock hazard with replacing metal with plastic. Good discussion on the topic of grounding.
Excellent point! I remember as a kid, there was a grounding rod inserted into the ground about 6 inches from the house I grew up in. My parents had 3 different additions put on this house, so I don't know if the grounding system was changed or moved, but I certainly do remember pulling the grounding rod out of the ground and using it as a spear in my cowboy & indian games.
.... never heard of UFER .... until now !
Thanks Charles :o)
Gary, there are several instances where changes to the plumbing system can compromise the electrical system---this is perhaps the worst of the them. Because plumbers aren't electricians, ensuring that the electrical system isn't compromised usually doesn't happen.
Jim, basically you have just illustrated the main reason these ground-rod methods of grounding are not as good as other methods. If you can easily pull it out of the ground----it is not making very good contact with the ground:)
Sheldon, you are welcome.
Chuckie bee,
I am in Mexico. I see that you are still blogging away.
Got an internet place nearby so will check in. By the way, tried to call the office and Nutsy must be so busy that the phone just keeps ringing. Any idea what he has going there
Charles, In the last few homes I built I used the "Ufer Ground" and agree that it generally beats other systems, but it's still imperfect due to possible subcontractor negligence. If the exposed rod isn't securely tied to the others it won't perform as designed. On the other hand, the exterior systems are easily compromised by poor soil conditions and the possibility of removal. For me it was important enough to supervise the installation so I would feel secure in the ability of the system to function properly.
Charlie,
This is weird but I thought that I just saw Nutsy. I am in an internet shop, saw this shadow and this figure ducked away. Must be relatives as he is suppossed to be running the firm as he did for you.
Amaging....you learn something new everyday.
Patricia AUlson/ Portsmouth NH Real Estate
This would be a fairly important bit of information for a potential buyer to know.
Steve, just keep trying your office----I am sure he is there somewhere. Then again you might want to check that smell coming from your luggage----might not be your socks.
John, the required 20' piece of rebar is all that is required for the Encased Grounding Conductor----that it is tied to all the other rebar would just be an added benefit. In our area this type of installation requires a special inspection prior to covering. If you screw up and don't do it you have to install a #4 copper wire ring all the way around the home at the footing-----contractors are not "forgetting"----for obvious reasons:)
Steve, you always need to watch your back with Nutsy.
Patricia----there is always too much to learn:)
Alan, I agree.
Charles - Once again, I've learned something here. I knew about the plumbing and rod in the ground method, but the Ufer way is news to me. Thanks for the info. I feel like I am much more informed on inspection issues thanks to your blog. I appreciate all the tips!
Matt, thanks---glad to be of help.
Hi Charles. Most of the older homes I inspect (1960's and earlier) have no ground rod, but I always recommended installing one. In my area when I updated my service I needed two (like you mentioned) that had to be 8 feet apart, and the first one had to be within 3 feet of the meter/conduit. So many ground clamps are also corroded on water main pipes, and this item never gets seen by anyone until an inspection. Hope you are keeping busy - I have been slow, but have been enjoying some time off. - Ray
Ray, yes, the pre-1960's houses often have no ground rods and they are particularly vulnerable to becoming ungrounded if the main water pipe is changed to plastic. I have been slow as well----there are some "rumblings" (or is that "grumbling?") of activity the last few days.
So how am I supposed to find out if my house is grounded properly? Where's the rod? This is a hard one but very informative!
Barbara, I don't think this is something you should try to tackle on your own. It is really a job for an Electrician.
Holy cow! You mean the clamp and the rod are supposed to be connected?...be right back...
That is right Jim----and connected really well too:)
Thanks for the interesting read :)
Katie, thanks for checking out my blog----and thanks for subcribing:)
I love it when you have a home with a well and the only ground connection is to the copper pipes. Only problem is the pipe coming in from the well is plastic. I have heard it argued that the water in the pipe will conduct the electricity to ground. I have seen this method quite a few times on new construction.
Actually that installation is half right because the water pipes are supposed to be bonded to ground. Unfortunately they forgot to do the other half.
James, don't let anybody kid you----it is very difficult to get water conductive. The water (blood) in our bodies is conducive only because of the amount of crud in it. Regular tap water that was conducive would not be drinkable:) There are lots of ways to houses to end up not properly grounded and bonded.
Charlie, I wasn't buying that argument, it is just some of the rationalizations your hear from time to time in this business. BTW is crud a scientific term.:)
James, I would be surprised if you did----it is just one of my pet peeves and used your comment as a way to get my point across. It is amazing how many people think water is conducive. I rarely have a student in my inspection classes that knows that it is not. I have several cool experiments that I use to show the reality of it.
Cool experiments! I love cool experiments. Does someones hair end up smoking when your done. :O
James, sending a private email your way---don't try this at home:)
Charlie,
Tell the rest of the story. After every demo the students think you got a perm.
I have a new one that utilizes Nutsy's wire walking skills:) How is he enoying "Cactus Glissading" by the way?
See I knew it, someone does end up with a new hair do. How cool is that?
Hi Charles, I found a similar problem at a home few days ago. Here take a look pipe was taped and the grounding clamp placed over it.
James---what's one more bad hair day:)
Frank---got a better picture?----really hard to see what exactly is going on.
Charles this is I hope a better picture for you to look at and see whats going on.
Frank----very nice:) Looks like it has been that way for a while as well.
Charlie,
What is the remark about Nutsy and cactus. Far as I know, he is still in
WA running the firm. Since he ran yours you know how good he is at that. You ought to do a blog with that pix you have of the hairdryer or whatever in the sink.
Hey Steve, I hear Nutsy is Nuts over the Inauguration?
When I tried to keep my kids grounded with discipline, I avoided the rod...
Jay----smart man, same here. They all turned out well in spite of me:)