How far can you run a grounding wire?

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deezel

Member
How far can you run a grounding wire from the main breaker panel.
Say the water main is on the other side of the building from the breaker panel?
 

bennie

Esteemed Member
Re: How far can you run a grounding wire?

You can run the ground electrode conductor from the panel to the water line. The answer is the same as the question :)
 

pierre

Senior Member
Re: How far can you run a grounding wire?

Bennie
Years ago when I was an apprentice, I had the best of luck to work with a fantastic general foreman. He was the best mechanic and most intelligent electrician I have met. When I would ask him questions, he would answer in a similiar method as you do. At first it really irritated me that I could not get a 'straight' answer. After a couple of months I realized he was really helping me. He has since pasted away, your response has brought his memory back to me. I bet the two of you would have hit it off really well.

Pierre
 

deezel

Member
Re: How far can you run a grounding wire?

So, in theory, you could run the ground electrode conductor 10,000 yards to a water main if you were so inclined? ;)

Or.... is there a distance limit?
 

websparky

Senior Member
Location
Cleveland, Ohio
Re: How far can you run a grounding wire?

No limit.

Do you have a situation where the water location is far and the degree of difficulty of installation is high?
 

bennie

Esteemed Member
Re: How far can you run a grounding wire?

When the water line is too far, change it to plastic, and drive two ground rods. Or do like me, I lie about it.

There is no point in using our natural resources for nonsense applications.

The earth connection should be as close as possible to the service entry point. It is ludicrous to allow an electrostatic charge to travel the full length of a dwelling.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Re: How far can you run a grounding wire?

deezel,
The limit is the size of the building and the relative locations of the water service entrance and the electrical service entrance. The code requires the use of the metal underground water piping as a grounding electrode, so you are required to use whatever length that it takes to get from one to the other.
Don
 

gwz2

Senior Member
Location
Indiana
Re: How far can you run a grounding wire?

In warmer climates why not just install more than 10 feet of metal piping in the earth by an outdoor water spigot ( near the Service Equipment location ) and leave it connected to the water, even if by a rubber hose.

Does the NEC require the 'metal water pipe' [250.52(A)(1)] to be the water sevice to a building, etc. ?

[ August 31, 2003, 06:25 PM: Message edited by: gwz2 ]
 

websparky

Senior Member
Location
Cleveland, Ohio
Re: How far can you run a grounding wire?

2002 NEC 90.1(C) Intention. This Code is not intended as a design specification or an instruction manual for untrained persons.
Handbook comment; The NEC is intended for use by capable engineers and electrical contractors in the design and/or installation of electrical equipment; by inspection authorities exercising legal jurisdiction over electrical installations; by property insurance inspectors; by qualified industrial, commercial, and residential electricians; and by instructors of electrical apprentices or students.
2002 NEC 250.53 Grounding Electrode System Installation.
(D) Metal Underground Water Pipe. Where used as a grounding electrode, metal underground water pipe shall meet the requirements of 250.53(D)(1) and (D)(2).
(1) Continuity. Continuity of the grounding path or the bonding connection to interior piping shall not rely on water meters or filtering devices and similar equipment.
(2) Supplemental Electrode Required. A metal underground water pipe shall be supplemented by an additional electrode of a type specified in 250.52(A)(2) through (A)(7). Where the supplemental electrode is a rod, pipe, or plate type, it shall comply with 250.56. The supplemental electrode shall be permitted to be bonded to the grounding electrode conductor, the grounded service-entrance conductor, the nonflexible grounded service raceway, or any grounded service enclosure.
[ August 31, 2003, 07:20 PM: Message edited by: websparky ]
 

tom baker

First Chief Moderator
Staff member
Re: How far can you run a grounding wire?

Dezel the water line can be used as a grounding electrode per 250.52 if it meets the requirements to be an electrode. Most these days do not. However you are still required to bond the metallic water piping per 250.104. These are two completly diffent concepts. Bennie is correct it does not make sense to run an electrostatic charge the length of a building, in this case we may be using the water pipe as a grounding electrode to stablize the voltage to ground and limit overvoltage. The bonding connection is to quickly and safely remove any voltage from the piping being energized. In both cases there are limits on lenght (or size), the grounding electrode case is less clear in the code for its length requirements. The note to 250.122 discussing increasing the size of the equipment grounding conductor.
I suggest you review the following defintions> Ground, grounded, grounding conductor, grounding electrode conductor, and bonding jumper. Your post asked about the "grounding wire" and per the NEC there is no such item, although I think I know what you mean.
 

wocolt

Member
Location
Ohio
Re: How far can you run a grounding wire?

How far can you run a no.6 to the water line meter connection and jumper connection for say a 100 amp service, the rule of thumb is approximately 100 feet.
They use the short term rating for this, ie 42.25 cm/amp for example a no.6 copper wire can carry 621 amps for 5 seconds flow of current the IR drop in the different sizes of grounding electrode conductors will be approximately 37 volts per 100 feet.
So if you had 150 feet of No.6 the resistance for 150 feet is 0.0462 ohms(0.491Ohms/1000ft)
then .0462 x 621 = 46 volts.
This would be a good indication to increase the size of the Grounding Electrode conductor.

WmColt
 

bennie

Esteemed Member
Re: How far can you run a grounding wire?

This is interesting, good math also. What creates this amount of current on the low side of a transmission system?
 

cripple

Senior Member
Re: How far can you run a grounding wire?

Table 250.66 covers the sizing of the grounding electrode conductor. The size of the grounding electrode are based on a 100' ft. per an IEEE study. A good general rule is, id the grounding electrode conductor is run greater than a 100 ft. and connected to a grounding electrode, it must be increased by 25 percent in size for each 25 ft. exceeding 100 ft. so this such be a design requirement and is not address by the NEC.
 

cripple

Senior Member
Re: How far can you run a grounding wire?

Sorry about my spelling. So there goes one more time.
Table 250.66 covers the sizing of the grounding electrode conductor. The size of the grounding electrode are based on a 100' ft. per an IEEE study. A good general rule is, if the grounding electrode conductor is run greater than a 100 ft. and connected to a grounding electrode, it must be increased by 25 percent in size for each 25 ft. exceeding 100 ft. so this such be a design requirement and is not address by the NEC.
 
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