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Old 07-23-2008, 03:10 PM   #1
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Upgrading Grounding System


I'm reading Wiring a House by Rex Cauldwell. I'd like to update the electrical system for my 1976 house. He advocates putting multiple ground rods at least 6 feet deep. What do y'all think?

Outside my meter, I have room for 2 ground rods and then the deck and patio get in the way.
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Old 07-23-2008, 04:26 PM   #2
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Upgrading Grounding System


Drive two ground rods and your good to go as far as the NEC is concerned. Rex also says that his above code installation is eight ground rods. That IMO is not necessary and an over installation considering the purpose they serve.
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Old 07-23-2008, 04:30 PM   #3
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Upgrading Grounding System


How many ground rod(s) does your system have currently?

Is there a ground wire connected to your water service?

What do you expect to accomplish by installing more rods?
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Old 07-23-2008, 06:49 PM   #4
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Upgrading Grounding System


The AHJ in my area requires 2 rods at least 5/8 diameter and 8 feet long to be driven at least 6 feet apart. In a recent continuing ed. class the instructor stated that if the rods were not as far apart as they are long it was a waste of time to drive multiple rods. What do you guys think?
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Old 07-23-2008, 07:03 PM   #5
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Upgrading Grounding System


In my area the code is for a single 5/8" x 8ft. rod.

But in my case it took a 2" x 25 ft. pipe into the water table! I had to ground my system to a water well to get a true zero potential.

I actually had 11 volts between the water well casing and an 8 ft. ground rod 20 feet away! With enough current to cause sparks!

If you do multiple rods be sure they a securely bonded together!
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Old 07-23-2008, 09:15 PM   #6
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Upgrading Grounding System


I replied to this on one of the other forums you posted to.
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Answers based on the 2008 & 2011 NEC. If you're on the '14 already I feel sorry for you.
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Old 07-23-2008, 10:00 PM   #7
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Upgrading Grounding System


You want an engineer's opinion?!
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Old 07-24-2008, 12:21 AM   #8
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Upgrading Grounding System


When it comes to grounding I'm always interested in what an engineer has to say..... Of course the term "engineer" has many perspectives. Such as Sanitary engineer, train engineer, plumbing engineer , mechanical engineer, electrical engineer, laundry engineer, civil engineer, landscape engineer, chemical engineer, nuclear engineer, structural engineer, industrial engineer, aerospace engineer,.......reminds me of Forest Gump when Bubba was telling him about all the kinds of shrimp his mom made.....

I knew a building engineer....ie...a person who sits in a chair in a small office and "LISTENS" to the building...... who thought grounding was something you did to your kids.

At anyrate... yeah... give us your opinion Jim...but for my benefit could you use words that ryhme cause engineering talk always sounded like poetry to me...I never understood what it meant.

Oh and a bit of advice ....never...call a Sanitary engineer a janitor....they really get pissed

Last edited by Stubbie; 07-24-2008 at 12:24 AM.
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Old 07-24-2008, 05:55 AM   #9
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Upgrading Grounding System


Quote:
Originally Posted by BigJimmy View Post
You want an engineer's opinion?!
NOOOOOO!

Actually, I'm an engineer myself.
A Bovine Fecal Matter Engineer.
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Sometimes I feel like if I answer any more questions it is like someone trying to climb over a fence to jump off a bridge and me giving them a boost.
Answers based on the 2008 & 2011 NEC. If you're on the '14 already I feel sorry for you.
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Old 07-24-2008, 06:44 AM   #10
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Upgrading Grounding System


Quote:
Originally Posted by Speedy Petey View Post
NOOOOOO!

Actually, I'm an engineer myself.
A Bovine Fecal Matter Engineer.
AH! A BS Artist!
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Old 07-24-2008, 06:59 AM   #11
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Upgrading Grounding System


I see no ground rods coming from my system. I don't know if it's grounded to the pipes. I want a good ground for my house. Cauldwell says that two ground rods are not enough to protect today's electronics. Fancy surge arrestors won't work if the house is not well grounded. Is there a way to measure what I have?
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Old 07-24-2008, 09:19 AM   #12
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Upgrading Grounding System


Measuring earth resistance is usually done using a Nul-balance resistance tester. I've done hundreds of these tests in switch yards. (easy but, no DIY job)

Here in Canada the code only requires a connection to the main water supply. IMHO that's enough. The code also requires two ground rods if the water supply is not available or in plastic. (and livestock installations).

I think there's way to much talk and hype about surge protection.

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Old 07-24-2008, 03:05 PM   #13
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Upgrading Grounding System


Looking in my utility room, I noticed an aluminum ground wire clamped to my water pipe. The wire is headed towards the panel. There is a jumper around the meter.

If this is my house ground, can I ground my TV antenna to a hose bibb?

In that same utility room, I noticed a telephone wire clamped to a 8 inch long copper pipe. The pipe was dangling from the wire, not attached to anything. Should I do something about that?
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Old 07-24-2008, 03:56 PM   #14
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Upgrading Grounding System


Sweaty

Grounding is very important for lightning protection and other very huge voltage events that may occur to your residence or power distribution grid.

Without huge cost it generally is not effective to install numerous ground rods at residences. First you need to have the proper test equipment to determine just what your electrode resistance to earth is. If you have no ground rods then the NEC only requires you to add two ground rods 5/8" by 8 feet if the first one is 25 ohms or more. Once you add the second rod the NEC could care less what the resistance is. So if it is still over 25 ohms you have gained nothing as far as protection quality to your dwelling and equipment.

In practically all cases low resistance (5 ohms or less) can only be obtained by getting large diameter rods (3/4") very deep in the ground. In large lightning areas like Florida large businesses with lots of equipment to protect may have 6 or more 3/4" 50 foot long rods driven over 50 foot deep in order to get this 5 ohms of resistance. So you see my point.

Yes.... you could improve the effectiveness of your grounding electrode system by obtaining very low resistance to your electrodes. But you need to get very deep with them or you could have 20 electodes (rods) and not gain a thing. 20 electrodes at 25 ohms is no better than 1 at 25 ohms. This is where Rex is off base in my opinion in his reasoning. His 8 electrodes all need to be under 25 ohms more like 10 or less to be effective as a system against lightning voltages. To have one at 25, one at 30, one at 20, one at 35, and so forth gains you very little. They all need to be below 25 ohms and more like 10 to provide high quality protection. You need to get 'deep' to obtain those kind of resistances.
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I noticed an aluminum ground wire clamped to my water pipe. The wire is headed towards the panel. There is a jumper around the meter.
I do not like aluminum for grounding electrode conductors, go with copper. #4 bare is what I usually use. This is your water pipe bond the attachment of the al should be within 5 feet of where the pipe leaves the ground to enter your dwelling and the metal pipe also needs to be in contact with the ground for at least 10 feet after leaving your home. Jumping the meter is required.

You cannot earth (ground) anything to a hose bib.

Last edited by Stubbie; 07-24-2008 at 04:07 PM.
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Old 07-26-2008, 11:49 AM   #15
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Upgrading Grounding System


If I add ground rods, would that create a ground loop with the water pipe?
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