Extra Ground Rods at opposite side of home

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Ravenvalor

Senior Member
Hello,

Are there any benefits to adding 2 - ground rods at opposite side of a home from where the service is?
I have to bond the gas meter there and was wondering if I should drive a couple of ground rods while I am over in the area.

Thanks A Bunch,
 

roger

Moderator
Staff member
Location
Fl
Occupation
Electrician
It would benefit the manufacturer and seller but that is about all I can come up with.

Roger
 

kwired

Electron manager
Location
NE Nebraska
Why do you have to bond the gas meter??


Do you happen to have a concrete encased electrode? If so forget using any ground rods, the CEE will be a better electrode than several ground rods will ever be (most cases).
 

Speedskater

Senior Member
Location
Cleveland, Ohio
I a word NO.

In fact it can be very dangerous!

This is what Bill Whitlock writes:

Since soil has resistance just like any other conductor, earth ground connections are not at zero
volts, with respect to each other or any other mystical or ?absolute? reference point. Code allows
the resistance to earth (measured with special techniques) of a residential ground rod to be as
high as 25 S. It is far too high to trip the circuit breaker under fault conditions in the dangerous
hookup of two ground rods (claimed to be a ?quieter? equipment ground). The soil resistance between
separate ground rods can also allow thousands of volts to develop between them if lightning strike
current should actually flow in one of them. This can seriously damage a computer modem, for
example, if it ?straddles? a computer (grounded via its power cord to the utility ground rod) and a
telephone line protected via a separate ground rod. [3] For this reason, other protective ground
connections (telephone, CATV, etc.) should be made to the same rod used for utility power, if at
all possible. If multiple ground rods are used, Code requires that they all must be bonded to the
main utility power grounding electrode. [4]

http://www.jensen-transformers.com/an/generic seminar.pdf
 

Ravenvalor

Senior Member
I a word NO.

In fact it can be very dangerous!

This is what Bill Whitlock writes:

Since soil has resistance just like any other conductor, earth ground connections are not at zero
volts, with respect to each other or any other mystical or ?absolute? reference point. Code allows
the resistance to earth (measured with special techniques) of a residential ground rod to be as
high as 25 S. It is far too high to trip the circuit breaker under fault conditions in the dangerous
hookup of two ground rods (claimed to be a ?quieter? equipment ground). The soil resistance between
separate ground rods can also allow thousands of volts to develop between them if lightning strike
current should actually flow in one of them. This can seriously damage a computer modem, for
example, if it ?straddles? a computer (grounded via its power cord to the utility ground rod) and a
telephone line protected via a separate ground rod. [3] For this reason, other protective ground
connections (telephone, CATV, etc.) should be made to the same rod used for utility power, if at
all possible. If multiple ground rods are used, Code requires that they all must be bonded to the
main utility power grounding electrode. [4]

http://www.jensen-transformers.com/an/generic seminar.pdf
Great Reply,
In this case I was considering bonding the 2 - new ground rods to the service which is where the 2 - existing ground rods are bonded to. Therefore they will be connected with a #6. See next post.
Thanks
 

Ravenvalor

Senior Member
Why do you have to bond the gas meter??


Do you happen to have a concrete encased electrode? If so forget using any ground rods, the CEE will be a better electrode than several ground rods will ever be (most cases).
Mechanical code requires the load side of the gas meter to be bonded with the service panel with #6 CU when installing CSST Stainless Gas Line.
 

kwired

Electron manager
Location
NE Nebraska
I a word NO.

In fact it can be very dangerous!

This is what Bill Whitlock writes:

Since soil has resistance just like any other conductor, earth ground connections are not at zero
volts, with respect to each other or any other mystical or ?absolute? reference point. Code allows
the resistance to earth (measured with special techniques) of a residential ground rod to be as
high as 25 S. It is far too high to trip the circuit breaker under fault conditions in the dangerous
hookup of two ground rods (claimed to be a ?quieter? equipment ground). The soil resistance between
separate ground rods can also allow thousands of volts to develop between them if lightning strike
current should actually flow in one of them. This can seriously damage a computer modem, for
example, if it ?straddles? a computer (grounded via its power cord to the utility ground rod) and a
telephone line protected via a separate ground rod. [3] For this reason, other protective ground
connections (telephone, CATV, etc.) should be made to the same rod used for utility power, if at
all possible. If multiple ground rods are used, Code requires that they all must be bonded to the
main utility power grounding electrode. [4]

http://www.jensen-transformers.com/an/generic seminar.pdf
But there is a low impedance conductor bonding them all together. The only time there is voltage between the ground rods is if the conductor between them is carrying current, the amount of voltage will be equal to the voltage drop on the conductor. This is why it is not a problem to install the additional rods but is also not required. By installing the additional rods you are lowering impedance to earth and can result in having undesirable neutral current flowing on equipment grounding conductors if that is what the rod is connected to.

Lightning is a different breed of problem, and there are many points of potential in any lightning event. There are ways to minimize them but just about impossible to say it won't happen.
 

roger

Moderator
Staff member
Location
Fl
Occupation
Electrician
I a word NO.

In fact it can be very dangerous!

This is what Bill Whitlock writes:

Code allows
the resistance to earth (measured with special techniques) of a residential ground rod to be as
high as 25 S. f
Actually the NEC allows it to be anything above 25 ohms, it could be in the Giga or higher range and be code compliant. The only time 25 ohms is required is if the electrode is a single rod

Roger
 

Speedskater

Senior Member
Location
Cleveland, Ohio
Actually the NEC allows it to be anything above 25 ohms, it could be in the Giga or higher range and be code compliant. The only time 25 ohms is required is if the electrode is a single rod
Roger
Very true. This paper was for live seminars and he was covering a lot of territory in a short time.

That darn "Ohm" symbol sure gets converted to lots of other letters by computers.

A few more of his many papers and articles:
http://store.haveinc.com/default.aspx
 

hillbilly1

Senior Member
Location
Atlanta,Ga
I have done this before, but it was due to the electrical service on one end of the house, with the cable and phones at the opposite end. The homeowner was loosing quite a few tv's and phones, and his insurance company was threatening to drop him. Drove two more rods at the phone and cable end, and buried a #4 bare copper between the two systems. He never had anymore problems.
 

kwired

Electron manager
Location
NE Nebraska
I have done this before, but it was due to the electrical service on one end of the house, with the cable and phones at the opposite end. The homeowner was loosing quite a few tv's and phones, and his insurance company was threatening to drop him. Drove two more rods at the phone and cable end, and buried a #4 bare copper between the two systems. He never had anymore problems.
Was the TV and phone systems bonded to electrical system before you added anything? A bonding jumper of almost any size should have taken care of this problem The additional ground rod will not take away much resistance in the ground path..
 
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