why?

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rwreuter

Senior Member
"A grounding conductor shall be installed with ALL feeders, even to detach structures"


WHY??? how does this help? and what does it prevent by doing this.

or

if you don't do it what can or will happen?
 

Buck Parrish

Senior Member
Location
NC & IN
It's possible the grounded conductor could be come energized at some time. After all AC is alternating current.

The equipment ground will help to prevent electrocutions, shocks, etc.... Because the houseing of the panel, etc... wil be isolated from the grounded conductor.
Where a three wire you would use the grounded conductor to ground or bond your equioment.
 
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triplstep

Member
Location
Aurora, Illinois
Welcome to the forum.

As Buck alluded to, safety.

Having a separate grounding conductor to remote buildings ensures the low-impedance path for ground-fault current to return to the service ground.
 

480sparky

Senior Member
Location
Iowegia
rwreuter;1126197[COLOR=black said:
]...........[/COLOR]if you don't do it what can or will happen?


Let's say you use the neutral conductor for grounding. And someday that neutral becomes open for whatever reason. At this point, all the grounded frames of whatever is connected to that circuit is energized (ie, has the same potential as the system voltage to ground). It could be a motor, a washing machine, a fridge....touch it and YOU are raised to the same potential. And if you're grounded at that time.... BZZZZZZZT!
 

rwreuter

Senior Member
I can understand that if at that seperate structure you are not setting up a grounding electrode system, ie 2 ground rods and water main.

I am building a house in a county where NO RULES exist, no permits, no inspections, no code.

The problem that I have is the electric co-op will not set or allow meters to be attached to the house. So I have to have a remote meter and disconnect. The new NEC now requires (where as in the past you could just run URD Triplex from the 200 amp disconnect (if of course no metal connected the two) and drive two ground rods and attach a bond to the water main if there was a metal one.

Technically I can do what I want but I don't understand the rational for the change in the NEC. I have wired hundreds of houses and have never heard of any problems, especially when wiring a detached garage with a grounding electrode system.

Just what does that 4th wire do? Does it create a back up to the back up (ie ground rods and water main)?

Do you guys understand where I am coming from and my predicament?
 
I can understand that if at that seperate structure you are not setting up a grounding electrode system, ie 2 ground rods and water main.

I am building a house in a county where NO RULES exist, no permits, no inspections, no code.


Technically I can do what I want but I don't understand the rational for the change in the NEC. I have wired hundreds of houses and have never heard of any problems, especially when wiring a detached garage with a grounding electrode system.

Just what does that 4th wire do? Does it create a back up to the back up (ie ground rods and water main)?

Do you guys understand where I am coming from and my predicament?[/quote]


The rules exist, you may just choose to ignore them.


Frankly, I do not understand your predicament. Install the equipment ground conductor and move on.


I am not sure where you live, but your jurisdiction may not even follow the '08 NEC. If not, then you are fretting for no reason. Check to see which rules do not exist in your area. ;)



P.S. You are an airplane mechanic and a licensed electrician, I think your training should have prepared you to understand the importance of following requirements...whether we like them or not.
 

triplstep

Member
Location
Aurora, Illinois
Just what does that 4th wire do? Does it create a back up to the back up (ie ground rods and water main)?

Do you guys understand where I am coming from and my predicament?

I think I understand.

The grounding conductor (4th wire) serves an entirely different purpose than the grounding electrode system of the ground rods and water main.

If you want to look upon it in terms of a back up, than it would be a backup to the grounded conductor.
 

rwreuter

Senior Member
I am fretting because there may actually be some valid reason for doing that.

I don't want to dismiss this rule if it stands for some good reason, not just because it is someone's hair brained idea (electrical engineers theories(as we all know the NEC grows larger every year, some good things and some VERY stupid things).

The reason I am baulking at it is because of cost, the URD triplex is under $2.00 a foot and the Mobile Home Quadplex (whatever it is) is around $4.00 a foot and I need to run it about 150 feet. The cost doubles just because of that one #4 conductor. A conductor that was never used before.

Sumner County Kansas, no rules, I could wire the house in knob and tube wiring if I wanted.
 

rwreuter

Senior Member
I understand the concept of a bond wire, but it is not called a bond wire.

A bond wire keeps everything that it is attached to the same resistance,
 

Rewire

Senior Member
I can understand that if at that seperate structure you are not setting up a grounding electrode system, ie 2 ground rods and water main.

I am building a house in a county where NO RULES exist, no permits, no inspections, no code.

The problem that I have is the electric co-op will not set or allow meters to be attached to the house. So I have to have a remote meter and disconnect. The new NEC now requires (where as in the past you could just run URD Triplex from the 200 amp disconnect (if of course no metal connected the two) and drive two ground rods and attach a bond to the water main if there was a metal one.

Technically I can do what I want but I don't understand the rational for the change in the NEC. I have wired hundreds of houses and have never heard of any problems, especially when wiring a detached garage with a grounding electrode system.

Just what does that 4th wire do? Does it create a back up to the back up (ie ground rods and water main)?

Do you guys understand where I am coming from and my predicament?

Its not a problem until you have a problem then you will have a problem, insurance adjusters know their is a NEC
 

rwreuter

Senior Member
Its not a problem until you have a problem then you will have a problem, insurance adjusters know their is a NEC

My point exactly!!!

That is one reason why I am looking into this. There are no rules but there are rules. No one cares that you don't do something that is not required until there is a problem.

If I can look at this and understand it for what it is, either good or frivolous (ie I have a better chance at winning the lottery) then I can make a decision, right or wrong at least it will be an informed decision.

There is help in a multitude of counselors.
 

mcclary's electrical

Senior Member
Location
VA
My point exactly!!!

That is one reason why I am looking into this. There are no rules but there are rules. No one cares that you don't do something that is not required until there is a problem.

If I can look at this and understand it for what it is, either good or frivolous (ie I have a better chance at winning the lottery) then I can make a decision, right or wrong at least it will be an informed decision.

There is help in a multitude of counselors.

Who are you to make a decision on this?? It should be done to code. If you're on 05' then you can still do it your way......if you're on 08' then you can't. There's no decision, do it right. Period.
 

480sparky

Senior Member
Location
Iowegia
If you wire it the way it should be, you'll feel better, and you may get a break on your insurance if you can document it. Also, it helps with the resale value.
 

rwreuter

Senior Member
Who are you to make a decision on this?? It should be done to code. If you're on 05' then you can still do it your way......if you're on 08' then you can't. There's no decision, do it right. Period.

LISTEN PLEASE....

i am not on any code, there are no code requirements there. i don't even have to pull an electrical permit. i just want to be safe and i don't want to waste money for something that doesn't need to be.

this is a new code requirement, obviously things ran fine before they placed this into existance. any one that is an electrician wire detached buildings that way before.

if you could do things any way you wanted I AM SURE that there would be portions of the NEC that you would exclude.
 

Rick Mack

Member
Location
Fort Mill, SC
Why? Grounding conductor to out building

Why? Grounding conductor to out building

Article 250.32 give details for grounding conductors to out buildings. There are several ifs, ands, and buts.
Go back and think about why the grounding conductor is used in the first
place. It provides a low resistance ground fault current path to trip the
breaker when an ungrounded conductor contacts an appliance or shop tool frame. Think about the path that the current follows if there is no equipment grounding conductor or other grounding path as allowed in Art. 250.118 in the feeder.

The current goes to the panel in the outbuilding over the equipment grounding conductor connected to the appliance. Then the current goes into the earth through the ground rod (max. 25 ohms resistance rod to ground).
The current flows through the earth (resistance?), then from earth to the ground rod at the service panel (another max. 25 ohms), then out on the service neutral to the transformer, then back to the service panel on the ungrounded service conductors where it applies the fault current to the breaker for the feeder. We have at least 50 ohms in this path.
I = E/R = 120 volts/50 ohms = 2.4 amps

This is hardly enough current to trip the feeder breaker, so the ungrounded conductor potential on the frame of the appliance is a trap for anyone who comes along and touches the appliance.

Mike Holt has provided some really good drawings in some newsletters that show clearly the ground fault current path and the need for good equipment grounding conductors throughout an installation.
 

Nium

Senior Member
Location
Bethlehem, PA
Grounding wasn't always required

Grounding wasn't always required

In an effort to make installations even safer a grounded conductor is required to be run with feeders because it provides a low impedance path back to source to clear fault currents. Fault current takes all and every path back to source therefor it will travel through the pipes (gas, water, etc.), ground rods, if the conduit for the feeders (if there is conduit) is metal then the conduit, thereby energizing all of them if someone were to get in series with that fault path and source then the high resistance of the human body wouldn't provide enough current to clear the fault but would instead become energized which could lead to electric shock or electrocution.
 
Sumner County Kansas, no rules, I could wire the house in knob and tube wiring if I wanted.


I went on the Kansas State website.
You are obligated to follow the rules and requirements of the 2005 NEC, ther are no amendments.

With that said, you do not need to install the additional equipment ground conductor. See 250.32 of the '05 NEC.

I hope you have a copy of the '05 NEC, seeing as you mention you are an licensed electrician.
 

SG-1

Senior Member
Multitude of Counselors

Multitude of Counselors

My point exactly!!!

That is one reason why I am looking into this. There are no rules but there are rules. No one cares that you don't do something that is not required until there is a problem.

If I can look at this and understand it for what it is, either good or frivolous (ie I have a better chance at winning the lottery) then I can make a decision, right or wrong at least it will be an informed decision.

There is help in a multitude of counselors.

The multitude of counselors is telling you to run the "extra wire" for a safer installation. 250.24(A)(5) prohibits the regrounding of the grounded conductor ( neutral ) past the service. This prevents unintended paths such as metal piping systems from carring neutral current. When the neutral is used the traditional way, you are using a normally current carring conductor for your safety ground. Current flowing generates voltage. You do not want current on the safety ground. It is better to use a fourth wire that only carries current if a problem exists. This way the only metal enclosures that are connected to a normally current carrying conductor is seperate from & outside of the house. This eliminates any chance of pyrophoric carbonization on the interior of the house due to neutral current finding a parallel path through any construction materials. It also gives you a test point to check the integrity of the wiring by throwing a clamp-on meter around it once or twice a year.

Go the Grounding vs Bonding forum and read the Big Picture Post. Also link to the power point presentation and watch it. Your decision will be more informed for it.

Hope you have many happy years in your new home.
 
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