Grounding Circuit

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  #1  
Old 12-12-02, 06:07 PM
J
jmacc
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Grounding Circuit

First, Thank you to evryone that has responded to my other questions..here's another one.

The current SEP is a 100 A. and was installed in 1974. I do plan to upgrade it but as happens in projects, money is the issue and I
am trying to take it one step at a time.

The current gound wire appears to be a solid 6 ga. copper run from the SEP to the copper water piper that is the house water
service line, between looking at the corrosion and looking at code,
I plan to add a second ground outside the house. While I would like to put in a 8ft. ground rod, the soil here is either hard clay
or extremely rocky, I doubt if I could get a rod down 8ft. Any suggestion for a alternate ground.

Also, any idea where I can look at the NEC online??
 
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Old 12-12-02, 06:32 PM
J
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The best way to drive the ground rod is to go to your local rental store, rent a large hammer drill with a ground rod attachment and fire away. Unless you have very large rocks, should takte about 20 mins. A place I go to look up some stuf on the NEC is called Mike Holt .com

good luck!
 
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Old 12-12-02, 07:21 PM
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jmacc
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Thanks, the rocks are the problem, within 5ft of ground level, I have rocks ranging from 12 in. to 3-4 ft in diameter. I live fairly close to a large lake and this was probably shoreline a long time ago. I was wonder about some other ways that I spotted in a couple books...using a steel plate or placing a grounding rod horizontal.
 
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Old 12-12-02, 08:13 PM
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If you have solid rock then drive the rod at a 45 degree angle. If that is not possible then dig a trench 10' long and bury the rod horizontally a minimum of 2' deep. The deeper the better.

If you have access to your structure's footing, lay a 2 awg copper wire the entire circumference of your building footing. Moiture is always around that footing. This 2 awg copper wire wrapping under the footing or along the side of your footing all around the building is the best ground electrode.
 
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Old 12-13-02, 07:12 AM
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Originally posted by jmacc
"Thanks, the rocks are the problem, within 5ft of ground level, I have rocks ranging from 12 in. to 3-4 ft in diameter. I live fairly close to a large lake and this was probably shoreline a long time ago. I was wonder about some other ways that I spotted in a couple books...using a steel plate or placing a grounding rod horizontal."

If your water line is of any significant length of buried metallic pipe you need only install the rods to code to guard against the plumbers or water utility workers future substitution of plastic pipe. If the buried portion of your metallic water line is relatively short you may want to consider investing some real effort so as to end up with at least a minimally effective grounding electrode system. Is your water supply from water mains or a well? If it is from metallic water mains then as long as your water service lateral is continuous to the main you have an excellent grounding electrode. If the water is from a well and your water line is continuous to a metal well casing then that leaves you in good shape to.

So as long as the rods really are just there to supplement the underground metal water pipe the rest is relatively easy.

First notice that I used the plural when referring to the rods. The minimum installation of driven or buried rods is two rods not less than six feet apart unless an actual measurement shows a ground impedance of 25 ohms or less on the first one. Since the instruments to measure ground impedance are expensive and the procedure can be involved the simplest answer is to install two driven or buried rods right from the start.

Second driven rods are seldom a fully effective grounding electrode because they usually do not reach to permanent moisture. So if your water pipe is not very long or is not electrically continuous you will need to devise an effective grounding electrode system without depending on the water pipe to do the whole job. Handyron's suggestion to install a ground ring around your home is a good one. If that is not possible we can make other suggestions on how to improve your systems grounding. You have only to ask!

Tom
 
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Old 12-15-02, 05:04 PM
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jmacc
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Grounding circuit - Part #2

Thanks for all the info..The house is currently grounded to the water service pipe which is 1'" copper and runs appoximately
75 feet under the basement and out to the street connection.

The second connection for ground will be 6ga solid copper run to a
8ft. copper grounding rod buried horizontal in a 10 ft. trench at a
depth of 48 inches..(which is at the frostline).

The reason I bring all this up is that I used a electrican text book
on residential wiring and it states that two grounds are required for code. Besides that, I like having the peace of mind of a SOLID
ground system.

Question # 1. I believe the second ground wire can start at the SEP or does it have to continue from the gounding point at the water pipe.

Question #2 Any idea how to clean and avoid corrosion on the copper water pipe.
 
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Old 12-15-02, 08:06 PM
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Re: Grounding circuit - Part #2

Originally posted by jmacc
"Thanks for all the info..The house is currently grounded to the water service pipe which is 1'" copper and runs appoximately
75 feet under the basement and out to the street connection.

The second connection for ground will be 6ga solid copper run to a
8ft. copper grounding rod buried horizontal in a 10 ft. trench at a
depth of 48 inches..(which is at the frostline).

The reason I bring all this up is that I used a electrican text book
on residential wiring and it states that two grounds are required for code. Besides that, I like having the peace of mind of a SOLID
ground system.

Question # 1. I believe the second ground wire can start at the SEP or does it have to continue from the gounding point at the water pipe.

Question #2 Any idea how to clean and avoid corrosion on the copper water pipe. "

jmacc
The 99 and 02 code requires two rods in the trench with the ends of the rods at least six feet apart. that will require at least twenty two feet of trench. Since you are using a trench to bury the rods let me suggest that you use number two bare copper as your Grounding Electrode Conductor (GEC). The larger size allows the GEC to serve as additional electrode by enlarging the soil contact area of the grounding electrode system.

In answer to question one you can run your second GEC from the water pipe, the drip loop of the service entry neutral conductor, or from the bonded buss bar of the service disconnecting means enclosure. Any of these connection points will satisfy the code requirement. You can even connect it to any metal service entry raceway.

In answer to question two you can buy abrasive tape in the plumbing section of any good hardware store. You take a short length and pull it back and forth across the surface of the pipe with the same motion that you pull a buffing rag across the toe of a shoe. Work your way around the pipe until the area that the clamp will attach to is bright copper. Make sure the clamp is bronze or brass. If it is galvanized iron or steel the two different metals of the pipe and the clamp will react with each other and corrosion will result.
--
Tom
 
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