Replies

1. 
   MSA1 | Jul 09, 2007 05:14am | #1

   I've never heard that question before. I think I always use 5/8". I dont know why though.

2. 
   DanH | Jul 09, 2007 05:47am | #2

   You don't use a rod, you use a "system". The rod may be part of it.

   So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
1. 
   kazm | Jul 09, 2007 06:00am | #3

   We are planning on several ground rods connected with #4 copper. Plus the "ufer" attached to the footing which I haven't quite figured out yet. Our local supplier who the electric company said would get us all the right supplies for a new service entrance supplied us with about 9/16 ground rods. We read in the code that 5/8 is required. Is the local supplier doing everything under code?????

1. 
   BillHartmann | Jul 09, 2007 08:39am | #5

   If you have a ufer ground then code does not require a ground rod.However, if you have metalic water supply lines, with the underground part at least 10 ft long then it must also be used as a ground electrode.However, local amendments and/or the power company rules might be different.Or they might be handling out old sheets that show ground rods because a ufer was not used..
   .
   A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.

3. 
   Luka | Jul 09, 2007 08:23am | #4

   You don't say where you are. Fill out that profile !

   Here, when I put in 200 amp service the grounding system required was two, ten foot 5/8 common rebar. 6 feet apart from each other. And a separate 1/4" solid copper run to each from the ground buss.

   I made it twelve foot rebars. And sunk all but about 4 inches of each.

   ---

   Yeh... That'll work.

1. 
   kazm | Jul 09, 2007 04:53pm | #6

   I am in Wyoming. We are sometimes about 20 years behind the rest of the country. The grounding rods are required at the service entrance. However we are told the local inspector will not pass inspection without the connection to the foundation rebar.

1. 
   BillHartmann | Jul 09, 2007 05:53pm | #7

   Here is the requirement (2005 NEC) for the ufer."(3) Concrete-Encased Electrode An electrode encased by at least 50 mm (2 in.) of
   concrete, located within and near the bottom of a concrete foundation or footing that is in
   direct contact with the earth, consisting of at least 6.0 m (20 ft) of one or more bare or
   zinc galvanized or other electrically conductive coated steel reinforcing bars or rods of
   not less than 13 mm ( 1/ 2 in.) in diameter, or consisting of at least 6.0 m (20 ft) of bare
   copper conductor not smaller than 4 AWG. Reinforcing bars shall be permitted to be
   bonded together by the usual steel tie wires or other effective means."This is some commentary about the ufer."Section 250.50 introduces the important concept of a ``grounding electrode system,'' in
   which all electrodes are bonded together, as illustrated in Exhibit 250.21. Rather than
   total reliance on a single grounding electrode to perform its function over the life of the
   electrical installation, the NEC encourages the formation of a system of electrodes
   ``that are present at each building or structure served.'' There is no doubt that building a
   system of electrodes adds a level of reliability and helps ensure system performance
   over a long period of time.
   This section was revised for the 2005 Code to clearly require the inclusion of a
   concrete-encased electrode, described in 250.52(A)(3), in the grounding electrode
   system for buildings or structures having a concrete footing or foundation with not less
   than 20 ft of surface area in direct contact with the earth. This requirement applies to
   all buildings and structures with a foundation and/or footing having 20 ft or more of 1/
   2 in. or greater electrically conductive reinforcing steel or 20 ft or more of bare copper
   not smaller than 4 AWG. However, an exception does exempt existing buildings and
   structures where access to the concrete-encased electrode would involve some type of
   demolition or similar activity that would disturb the existing construction. Because the
   installation of the footings and foundation is one of the first elements of a construction
   project and in most cases has long been completed by the time the electric service is
   installed, this revised text necessitates an awareness and coordinated effort on the part
   of designers and the construction trades in making sure that the concrete-encased
   electrode is incorporated into the grounding electrode system."The picture shows a ufer ground.I am also concerned about how to keep the ground electrode conductor safe before getting the foundation and walls finished. If this is a slab and/or shallow footings it would not be that bad.But if you have basement or crwalsapce construction with footing 4-8 ft underground then I think that it woudl be difficult for keep the conductor protected.What I would want to do is to use tied up turned rebar. Then tie that to the rebar in the foundation. And mount a box in the foundation so that when the forms are stripped you have access to the rebar and you can make connections afterwards.But I would pass that by the inspector first.Here is the ground rod requirements."(5) Rod and Pipe Electrodes Rod and pipe electrodes shall not be less than 2.5 m (8 ft)
   in length and shall consist of the following materials.
   (a) Electrodes of pipe or conduit shall not be smaller than metric designator 21 (trade
   size 3/ 4) and, where of iron or steel, shall have the outer surface galvanized or
   otherwise metal-coated for corrosion protection.
   (b) Electrodes of rods of iron or steel shall be at least 15.87 mm ( 5/ 8 in.) in diameter.
   Stainless steel rods less than 16 mm ( 5/ 8 in.) in diameter, nonferrous rods, or
   their equivalent shall be listed and shall not be less than 13 mm ( 1/ 2 in.) in
   diameter.""250.53 Grounding Electrode System Installation
   FPN:See 547.9 and 547.10 for special grounding and bonding requirements for agricultural
   buildings.
   (A) Rod, Pipe, and Plate Electrodes Where practicable, rod, pipe, and plate electrodes
   shall be embedded below permanent moisture level. Rod, pipe, and plate electrodes shall
   be free from nonconductive coatings such as paint or enamel.
   (B) Electrode Spacing Where more than one of the electrodes of the type specified in
   250.52(A)(5) or (A)(6) are used, each electrode of one grounding system (including that
   used for air terminals) shall not be less than 1.83 m (6 ft) from any other electrode of
   another grounding system. Two or more grounding electrodes that are effectively bonded
   together shall be considered a single grounding electrode system.""(G) Rod and Pipe Electrodes The electrode shall be installed such that at least 2.44 m (8
   ft) of length is in contact with the soil. It shall be driven to a depth of not less than 2.44 m
   (8 ft) except that, where rock bottom is encountered, the electrode shall be driven at an
   oblique angle not to exceed 45 degrees from the vertical or, where rock bottom is
   encountered at an angle up to 45 degrees, the electrode shall be permitted to be buried in
   a trench that is at least 750 mm (30 in.) deep. The upper end of the electrode shall be
   flush with or below ground level unless the aboveground end and the grounding electrode
   conductor attachment are protected against physical damage as specified in 250.10.""250.56 Resistance of Rod, Pipe, and Plate Electrodes
   A single electrode consisting of a rod, pipe, or plate that does not have a resistance to
   ground of 25 ohms or less shall be augmented by one additional electrode of any of the
   types specified by 250.52(A)(2) through (A)(7). Where multiple rod, pipe, or plate
   electrodes are installed to meet the requirements of this section, they shall not be less than
   1.8 m (6 ft) apart.
   FPN: The paralleling efficiency of rods longer than 2.5 m (8 ft) is improved by spacing greater
   than 1.8 m (6 ft)."And a drawing show the orientation of ground rods..
   .
   A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.

1. 
   kazm | Jul 09, 2007 06:53pm | #8

   This isn't the first time I have received needed information from you. Thanks. This is a do it yourself project my husband and I are working on but we are detailed oriented and know how to read and comprehend. We will do some studying on the information you forwarded. We have received valuable comments and information from all the folks at Breaktime and I am sure there will be other questions as we go along.

4. 
   renosteinke | Jul 09, 2007 11:28pm | #9

   The size of the service has absolutely nothing to do with the size of the ground rod.

   Of greater concern to you are A) your local codes B) local soil conditions and C) how difficult it will be to drive the rod.

   Around here, we are required to use a 10' rod. Since the ground is quite rocky, this means a 5/8 copper clad steel rod is preferred.

1. 
   FastEddie | Jul 10, 2007 12:35am | #10

   Just finished a bank branch in Roanoke.  Freestanding 4300 sf building.  We used 3 @ 20 ft 5/8" copper ground rods, spaced ina triangle with 30 ft sides, connected by cad welded 4/0 bare cable.  That should do the trick."Put your creed in your deed."   Emerson

   "When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it."  T. Roosevelt

1. 
   BillHartmann | Jul 10, 2007 12:43am | #11

   Why no ufer.Should be lots of footings for a building like that..
   .
   A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.

2. 
   maddog3 | Jul 10, 2007 12:45am | #12

   those "deltas" are pretty much standard on commercial work around here heavy industries bond every beam with 500MCM ....

   .

   .

   ., wer ist jetzt der Idiot ?

5. 
   AzDiscDog | Jul 10, 2007 01:39am | #13

   When I re-did the service on my house, I used 2 5/8 copper clad rods. Mostly I wanted the thicker rods to make it easier to drive them. Price difference is minimal, or at least it was for me.

   Spaced 'em 6' apart and tied them with #4 cu, if I recall correctly. Also tied it back to the house's water supply (mostly to make the inspector happy).

   They need to be buried 12" under as well. I ran #4 in plastic conduit between the two rods in case someone ever digs in that area in the future.

   Glen

1. 
   brownbagg | Jul 10, 2007 02:05am | #14

   I install three 5/8 rods ten feet apart. I failed my inspection by my wally world electrical inspector because I had more than one rod. so I drove the other two below ground. and passed

1. 
   SamT | Jul 10, 2007 04:49am | #15

   failed my inspection by my wally world electrical inspector because I had more than one rodHenh! Henh! henh! Idjits.SamT