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Old 10-19-2008, 06:03 AM   #1
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Grounding, generator switch


I moved your question from the thread it was posted on to a new thread. TheKCtermite

> read up on the nec 2008, you will need to sink 2 ground rods (unless you already have 2)

Why? My 1960's house is grounded thru the wall where the well pipes enter; so presumably to the casing. I know that nowadays a secondary ground is used, but why does upgrading service necessitate changing the ground, and also dual grounds?

I'm considering upgrading as well, and I can get a retired electrician to advise me. Still need to see if the POCO has to upgrade their feeder though.

I have a generator switch so this question is just for reference -- Is it safe to pull / install the meter when the feed is energized?
TIA
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Old 10-19-2008, 06:54 AM   #2
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Grounding, generator switch


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Originally Posted by V=IR View Post
> read up on the nec 2008, you will need to sink 2 ground rods (unless you already have 2)

Why? My 1960's house is grounded thru the wall where the well pipes enter; so presumably to the casing. I know that nowadays a secondary ground is used, but why does upgrading service necessitate changing the ground, and also dual grounds?
Why???
Because the grounding/bonding of the service is PART OF the service. They are most certainly required to be upgraded.



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I'm considering upgrading as well, and I can get a retired electrician to advise me. Still need to see if the POCO has to upgrade their feeder though.
The POCO's service drop is not your concern. They will replace it at their disgression.
If it is an underground lateral then in many areas you own and maintain it. It is up to your to contact your POCO to find out what the requirements are for a service upgrade.



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I have a generator switch so this question is just for reference -- Is it safe to pull / install the meter when the feed is energized?
It is extremely unsafe, and illegal, for anyone untrained or unqualified to EVER pull an electric meter. Period.
Those who are qualified know how to do it and what is safe.

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Old 10-19-2008, 03:46 PM   #3
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Grounding, generator switch


Before I got the generator switch, linemen appeciated that I pulled it to prevent backfeed after a hurricane knocked everything out. But I always managed to be there when they arrived at the transformer serving my house and we put it back before reenergizing the feed.

Determining if the POCO needs to do anything to the feed is part of estimating the cost.

I can understand a requirement to upgrade to two grounds, but is the well casing no longer acceptable?

I have a recollection that a driven rod has to be some minimum distance from the house (as well as 8' deep and whatever it is from the other rod) ??

Finding a good location to drive a rod could be a real problem. There's asphalt on top of rocky fill, there's a lot of sand fill, and one side is near the top of a steep slope. And trenching the wire to the house pretty much impossible if its not right next to the house. The well head itself is buried about six feet under.

There is some kind of rod a foot away from the house and I'm wondering if it was at some point used as a lightning rod or TV roof antenna ground.

Are rods driven by a big guy with a sledge or is there some machine (hopefully small enough to get thru small access points)?

What about driving a rod horizontally from near the bottom of a retaining wall? But its sand fill on the other side. OTOH the rod could be longer than 8'.

The electric improvements are incidental to replacing ALL the copper pipe; I had a leak that ruined a room and two more in the couple months since, so its got to be replaced with plastic due to acid water. So I will need to run a dedicated ground wire from the breaker panel to the well penetration.

All I really don't want to live without is a mini-tank water heater under the bathoom sink; I might be able to find one breaker in the existing panel that's not already a duplex and run 15 amps to it.
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Old 10-19-2008, 04:42 PM   #4
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I can understand a requirement to upgrade to two grounds, but is the well casing no longer acceptable?
The wire going to a metallic water pipe is NOT going to the well casing. I don't know how the well casing even got into this conversation.


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I have a recollection that a driven rod has to be some minimum distance from the house (as well as 8' deep and whatever it is from the other rod) ??
There is NO minimum distance from the house. You need to use an 8' rod driven flush or deeper. Supplemental rods must be at least 6' away from the other.


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Finding a good location to drive a rod could be a real problem. There's asphalt on top of rocky fill, there's a lot of sand fill, and one side is near the top of a steep slope. And trenching the wire to the house pretty much impossible if its not right next to the house.
Welcome to my world.



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Are rods driven by a big guy with a sledge or is there some machine (hopefully small enough to get thru small access points)?
Either by hand sledge, or a driver in a large hammer drill, or some other means. Which ever is available.



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What about driving a rod horizontally from near the bottom of a retaining wall? But its sand fill on the other side. OTOH the rod could be longer than 8'.
A rod can be driven up to a 45 degree angle, or buried in a trench 24" deep.



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The electric improvements are incidental to replacing ALL the copper pipe; I had a leak that ruined a room and two more in the couple months since, so its got to be replaced with plastic due to acid water. So I will need to run a dedicated ground wire from the breaker panel to the well penetration.
If the water pipe entering the house is metallci then yes, you have to connect to this pipe within 5' of where it enters. The well has NOTHING to do with it.
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Old 10-19-2008, 11:23 PM   #5
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Grounding, generator switch


>the wire going to a metallic water pipe is NOT going to the well casing. I don't know how the well casing even got into this conversation.

Breaker box
ground wire
clamp
nearest point of water pipe 12 feet away, on other side of garage
...
water pipe point near entrance of well pipes
clamp
wire which disappears into the penetration for the well pipes, presumably to the well casing as a ground.

Its a jet pump, so its not a ground for a pump at the bottom of the well.

The jet pump is on a dedicated circuit (as far as I know) and has an equipment ground wire in the cable.

When the copper goes away, I need to run a new wire from the breaker box straight thru the house to the well pipe wire location. Less than 50 feet.

***

Which reminds me -- the stub pipe from the water tank to the main pipe has been replaced with plastic. The pump is mounted on top of the tank. Do I want to ground the pump to the copper pipe directly, or just rely on the equipment ground wire in the cable that goes all the way back to the breaker box?

I _think_ its correct as is, because a short circuit might travel down both paths and maybe not trip the breaker ?

Last edited by V=IR; 10-19-2008 at 11:41 PM.
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Old 10-20-2008, 05:22 AM   #6
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Grounding, generator switch


Oh, I see. You are presuming the well casing is being used as a ground.
I doubt it. This is not typical. In fact, is there even a well casing?

I really think you are over thinking this. You need to get the grounding and bonding requirements down pat before you do any work.
Ask your local building department what the requirements are and if they differ from the NEC.
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Old 10-21-2008, 11:20 PM   #7
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Grounding, generator switch


If that wire going out the well penetration is not the ground, then there is no ground.

If it doesn't go to a metal well casing, then it must go to a buried grounding electrode. Who cares which?

That wire is the only bare copper wire coming out of the panel. AFAIK it MUST be the grounding wire.

The pipes from the well are plastic. The gas service pipe is plastic until the rise to the meter. I just looked at the gas penetration point, and there is no wire exiting; so the gas piping is not being used to take the ground out of the house.

You know everything that I do. Where's the ground ?????
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Old 10-21-2008, 11:44 PM   #8
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Grounding, generator switch


This text book doesn't seem to talk about the NEC requirements for using a buried grounding electrode, except as a supplement to buried water piping.

If I presume that the code at the time of building allowed a single ground rod electrode, and I presume that the house met code, then the wire leads to an electrode.

But I don't know if a single electrode is acceptable today, even if it was then.

And I think if it does, I still ought to put the 4AWG grounding conductor inside a metal raceway.
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Old 10-22-2008, 12:28 AM   #9
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This text book doesn't seem to talk about the NEC requirements for using a buried grounding electrode, except as a supplement to buried water piping.
That's it. If you have a grounding electrode that consists of a metal water pipe (including well casings) in contact with the earth for more than 10 feet, then you must supplement it with another electrode, as per 250.53(D)(2). It isn't necessarily a rod. And if you have a concrete encased electrode, then you don't need a supplemental.

Quote:
If I presume that the code at the time of building allowed a single ground rod electrode, and I presume that the house met code, then the wire leads to an electrode.

But I don't know if a single electrode is acceptable today, even if it was then.
It is still acceptable now, IF you can verify that the electrode has a resistance of 25 ohms or less to earth. But the code says that if we can't meet the 25 ohms, then another electrode shall be installed, with no further requirement for resistance verification. So electricians started driving two rods. It was easier than having a single rod verified.

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And I think if it does, I still ought to put the 4AWG grounding conductor inside a metal raceway.
If you put it in a metal raceway, then you need to connect it to both ends of the raceway.
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Old 10-23-2008, 01:58 PM   #10
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Grounding, generator switch


Gotta presume that this wire to 50' pipe to bare wire going somewhere met code in the late 1960's. The well pipes are plastic, but there's 60+ feet of well casing. Don't know if its metal; there is a notation that says it was replaced in 1979.

Might the wire be snaked down into the concrete footer for a who'sits type ground (the guy with the funny name they named it after) ?

I just read that when several hundred amps discharge down a ground wire, only 5 amps went down the wire and the rest thru thru the metal raceway or conduit, because of the skin effect. Strikes me as odd that it wasn't a problem in the 1960's

There would still be a foot or so of bare wire going thru the penetration, which would be the weak spot.

I understand most electricians don't have the expensive eqpt for testing ground ohms; any idea how much it would cost for someone to come out and test it? Might the POCO do it?
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Old 10-23-2008, 02:10 PM   #11
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Gotta presume that this wire to 50' pipe to bare wire going somewhere met code in the late 1960's. The well pipes are plastic, but there's 60+ feet of well casing. Don't know if its metal; there is a notation that says it was replaced in 1979.

Might the wire be snaked down into the concrete footer for a who'sits type ground (the guy with the funny name they named it after) ?

I just read that when several hundred amps discharge down a ground wire, only 5 amps went down the wire and the rest thru thru the metal raceway or conduit, because of the skin effect. Strikes me as odd that it wasn't a problem in the 1960's

There would still be a foot or so of bare wire going thru the penetration, which would be the weak spot.

I understand most electricians don't have the expensive eqpt for testing ground ohms; any idea how much it would cost for someone to come out and test it? Might the POCO do it?
Ufer ground is the who's it. Why not drive two rods and be done? In fact, there is no need to do anything with the existing wire. Leave it running to wherever it is running. Drive your rods, connect them with a #6 copper conductor, the use a split-bolt connector to tie that into the existing wire.

And it was a problem in the 60s. It has never been allowable to run a grounding electrode conductor inside a metal raceway without bonding it to both ends. And this isn't due to the skin effect, as is the case during faults. It is because of the choke effect of the induced current in the conduit during high current events, like lightning.
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Old 10-23-2008, 11:16 PM   #12
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Grounding, generator switch


Hmm, what I read might have related to lightning strikes...

The copper pipe is going away; I'm replacing the whole plumbing system with plastic because of leaky pipes.

Does NEC have a limit on the length of the grounding conductor, between the panel board and the location of the grounding electrode? I would like to just run a new length of 4 AWG wire /conduit to where the existing wire goes into the penetration in the wall, and the buried grounding electrode beyond.

Is bare 4 AWG wire good or merely minimum, as a grounding conductor? What benefits do I get from using metal conduit?

Last edited by V=IR; 10-23-2008 at 11:20 PM.
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Old 10-24-2008, 02:07 PM   #13
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Hmm, what I read might have related to lightning strikes...

The copper pipe is going away; I'm replacing the whole plumbing system with plastic because of leaky pipes.

Does NEC have a limit on the length of the grounding conductor, between the panel board and the location of the grounding electrode? I would like to just run a new length of 4 AWG wire /conduit to where the existing wire goes into the penetration in the wall, and the buried grounding electrode beyond.

Is bare 4 AWG wire good or merely minimum, as a grounding conductor? What benefits do I get from using metal conduit?
There is no length limit, but it should of course be as short as is possible. #6 is actually the maximum required for rod type electrodes, by the NEC. You can go larger, but you don't have to. Conduit, of any type provides an added layer of mechanical protection for the conductor. #4 was used likely because this isn't a rod type electrode conductor. The #4 would have been sized as a water line electrode, likely.
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Old 10-27-2008, 12:38 AM   #14
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Grounding, generator switch


>#4 was used likely because this isn't a rod type electrode conductor. The #4 would have been sized as a water line electrode, likely.

But it can't be a water line electrode because the lines from the well are plastic.

Would they have used #4 because the water line was being used as the majority of the grounding conductor's length leading to an electrode?

I'll have to go mic the wire and confirm that it is #4.
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Old 10-27-2008, 09:14 AM   #15
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>#4 was used likely because this isn't a rod type electrode conductor. The #4 would have been sized as a water line electrode, likely.

But it can't be a water line electrode because the lines from the well are plastic.

Would they have used #4 because the water line was being used as the majority of the grounding conductor's length leading to an electrode?

I'll have to go mic the wire and confirm that it is #4.
No need to get so deep into it. I guess it boils down to this: that wire likely went to your well. If this is no longer the source of your water or the setup is plastic, then that wire no longer needs to go there and instead needs to tie to another electrode. This can be one of several, including rod and pipe, plate electrodes, building steel and concrete encased electrodes.

But if you have a metal well casing, and you can verify that the wire is connected to it, you probably won't find or make a better connection to earth.

Make a jumper long enough so that you can use an ohm meter to check the resistance between the well casing in the bare conductor in the house. It they are solidly connected, it would read as a dead short.

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