Grounding Rods

[Buckeye_Guy]

I installed a main panel in my barn.

According to NEC, the panel needs to be grounded to the earth via copper rods outside my barn. I believe I need to install two copper rods, each at least 8' in length, and at least 6' apart. The wire between the panel and copper rods needs to be #6 AWG or larger.

Now... let's say I install the copper rods just outside my barn (like 1 foot from the outside wall). Let's also say a few years from now I want to install a concrete skirt around the barn. The contractor is going to dig up the top soil around the barn, pour gravel, etc. What about the copper rods in the ground?

To cut to the chase... I plan on installing the copper rods in the next week or two. How should I install them so that pouring a concrete skirt around the barn won't be a problem when it comes time to do it?

 

[sberry]

I might consider running them to an accessable place and ideally under a drip edge. If this is new there may be other issues. You should list location, climate is a factor.

 

[Speedy Petey]

Just install them so the top is below grade. There is nothing in the code that says the rods need to be accessible.

 

[Buckeye_Guy]

Ohio.

I will eventually pour a concrete skirt on each side of the barn. The skirt will probably be 8 feet wide.

I am not sure how to handle this for the grounding rods.

Should I place the rods 12 feet away from the barn, so they will be beyond the concrete skirt once it's poured?

 

[slodat]

You can have the copper wire pass through the concrete. At my place whoever build the place bonded the ground to the rebar in the concrete and the wire passed through a piece of 1/2" pvc conduit embedded in the concrete.. I know the rebar is bonded because I did a 2 point ground test out of curiosity (there's a piece of exposed rebar).

 

[wyliesdiesels]

I installed a main panel in my barn.

According to NEC, the panel needs to be grounded to the earth via copper rods outside my barn. I believe I need to install two copper rods, each at least 8' in length, and at least 6' apart. The wire between the panel and copper rods needs to be #6 AWG or larger.

Now... let's say I install the copper rods just outside my barn (like 1 foot from the outside wall). Let's also say a few years from now I want to install a concrete skirt around the barn. The contractor is going to dig up the top soil around the barn, pour gravel, etc. What about the copper rods in the ground?

To cut to the chase... I plan on installing the copper rods in the next week or two. How should I install them so that pouring a concrete skirt around the barn won't be a problem when it comes time to do it?

U said u installed a new main service panel. Is this a replacemnet panel or a new barn or a new service on an existing barn?

If new barn, why didnt u use a UFER ground?

what size is the service?

#8 is the smallest wire u can use for a GEC but needs to be in conduit.

#6 is the largest needed going to rods and doesnt need protection as long as its not subject to damage.

To keep the rods accessable for future use, u can use a precast curb valve box.

http://m.platt.com/platt-electric-s...astle-Precast/1000370/Products.aspx?pid=15341

 

[slodat]

Thanks for posting that box info! That's slick.

 

[wyliesdiesels]

We use those all the time for communication tower grounding. But thats a different animal.

 

[sberry]

I guess I didn't pay attn. to Buckeye for location.

 

[Buckeye_Guy]

U said u installed a new main service panel. Is this a replacemnet panel or a new barn or a new service on an existing barn?

New barn (40' X 40' x 10'), new panel. It's a main panel (120/240 V), not a sub panel. I think it's a 120 A panel.

If new barn, why didnt u use a UFER ground?

Not even sure what that is.

I installed the panel a couple years ago, and it works fine. But I haven't yet installed the 8' copper ground rods. Hence my original question.

Thanks

 

[Buckeye_Guy]

My cousin Barbra is married to an electrician. I asked her to ask her husband about it. His response:

You're correct about NEC of ground rods. There is no code stating how close the ground rods have to be to the panel so you could put them far enough out away from future concrete work as you need to. You can run the #6 in conduit. You could bury the rods deep enough below concrete level but he thinks concrete eats away at the rods eventually and then if you ever have a problem you're screwed since they are buried under concrete.

So I think I'll just install the rods 12' away from the barn.

 

[wyliesdiesels]

New barn (40' X 40' x 10'), new panel. It's a main panel (120/240 V), not a sub panel. I think it's a 120 A panel.


Not even sure what that is.

I installed the panel a couple years ago, and it works fine. But I haven't yet installed the 8' copper ground rods. Hence my original question.

Thanks

Ok the panel may be setup as a main service panel but what i was trying to get at is whether the barn has its own service or is it being fed from another building? And the voltage of a panel has nothing to do with whether its the main service panel(where the feed from the PoCo comes in at)...

A UFER grounding electrode uses the rebar in the footing....All new buildings are required to use a UFER ground unless the slab doesnt come into direct contact with soil ie. vapor barrier...

If youre concerned about access to the rod after pouring concrete u could use a curb valve box

 

[VDubJoe]

Whatever ground you do make sure to test it. Where I live I had to drive 16 feet on mine and my neighbors.
In my county they don't test them. So most electricians stick a 6' rod in the ground and let it go. Doesn't do very good in sugar sand.
I was a troubleshooter for the power company for 18 years. Went on a lot of bad neutral problems. Had one where the overhead nuet. was broken and the customer had no issues.

 

[Gary_montague]

They are not copper rods. They are copper plated steel . new code in michigan last i knew required new building to have re-rod tied together and extend the full distance of footings, which is usually a loop is this is below frost line. #4 copper with bond to re-rod then brought up to sub panel . i am not sure about the sub to main except they need to be tied together. my main is a 200 exterior breaker that feeds a 200 a panel in house. I had to question why the re rod did not need to be plated also. But who can really explain grounding requirements anyway? Most inspectors pretend they understand grounding .

 

[Aceman]

You don't need copper coated rods, 5/8" galvanized is just fine. Sink them in the ground deep enough the slab won't expose them, or if you really want too, dig out past the apron and sink them. I usually put them right beside the building, if I know a slab or sidewalk is going in later I just sink them a few inches deeper so they don't get dug up.

They don't need to be accessible later as long as they are inspected when they are put in.

 

[Speedy Petey]

Whatever ground you do make sure to test it. Where I live I had to drive 16 feet on mine and my neighbors.
In my county they don't test them. So most electricians stick a 6' rod in the ground and let it go. Doesn't do very good in sugar sand.
I was a troubleshooter for the power company for 18 years. Went on a lot of bad neutral problems. Had one where the overhead nuet. was broken and the customer had no issues.

Can you tell me what ground rods have to do with neutrals? |

And how do you propose a DIYer test a ground rod? Go out and buy the required tester?

Also, most electricians don't stick a 6' rod in the ground. We use 8' rods, and typically two, because that is all the code requires. Period.

 

[Jlarson]

Sink the rods and pour over them, simple as that.

 

[VDubJoe]

Speedy Pete
I stand corrected , around here they use 6' rods a lot. I'm guessing it is because its cheaper and easier to install. And who's going to check it.
Isn't it in the Nec code to check to be sure the resistance is 25 ohms' or less.

I stand corrected. It tech. doesn't have anything to do with the nuet. But if the line side nuet. goes south it will keep load side voltage variances to a minimum.
It has a lot to do with helping surges dissipate safely when coming from the line side of the service. Especially lighting. Which down here is a big issue.
And sec. line surges from conductor's making contact. Which is also a very common thing here.

That's why where I worked we installed and tested all ground rods at every transformer and installed them every few poles with arrestors.

And no the average person is not going to go buy a tester.

 

[Jlarson]

You don't need to prove 25 or less if you use 2 rods, that's why we do it. It's not worth testing.

 

[Speedy Petey]

Speedy Pete
I stand corrected , around here they use 6' rods a lot. I'm guessing it is because its cheaper and easier to install. And who's going to check it.
Isn't it in the Nec code to check to be sure the resistance is 25 ohms' or less.

6' ground rods are not code acceptable. They much be 8' minimum.

Also, as Jlarson says, it is not code that they be checked for 25 ohms. If you do happen to check it, and not meet the 25 ohms, then you must install another rod, but that's it. You are NOT required to install any more or meet the 25 ohms.

 

[bczygan]

If you cover the rods with concrete, can't that allow the soil below to dry out to the point where grounding is ineffective?

 

[Jlarson]

Not an NEC concern and not anything to worry about.

Ground rods are really just installed because the code says we have too, they serve little purpose, as does any other earth ground in low voltage electrical systems.

 

[wyliesdiesels]

Not an NEC concern and not anything to worry about.

Ground rods are really just installed because the code says we have too, they serve little purpose, as does any other earth ground in low voltage electrical systems.

I sure hope youre kidding and being sarcastic!

 

[alfredeneuman]

Not an NEC concern and not anything to worry about.

Ground rods are really just installed because the code says we have too, they serve little purpose, as does any other earth ground in low voltage electrical systems.

What about this?

Without one you have a good chance of all the wiring and anything hooked to it up being burnt to a crisp!

 

[Jlarson]

They only provide marginal protection in cases of a lightning strike or a primary to secondary fault, but in the vast majority of cases the house's electrical system and stuff connected to it still will suffer significant damage. One or two ground rods and a piece of #6 solid is going to make very little difference.

If you are really worried about lightning damage put in a properly engineered and installed LPS.

 

[checkthisout]

They only provide marginal protection in cases of a lightning strike or a primary to secondary fault, but in the vast majority of cases the house's electrical system and stuff connected to it still will suffer significant damage. One or two ground rods and a piece of #6 solid is going to make very little difference.

If you are really worried about lightning damage put in a properly engineered and installed LPS.

Tree in front of my grannies house got hit by lightning. K?

Spiraled the bark, blew up a stump at the bottom taking out a window in the house.

Blew a phone off the wall, bubbled the linoleum where the phone wire came in, blew the box off the little phone junction box outside and blew a heating duct apart in the crawlspace.

Everything connected to the house electrical and the electrical itself was fine.

Guessing grounding helped that be the case.

 

[Jlarson]

Just because there wasn't any damage to any appliances doesn't mean they isn't concealed damage to conductors and splices. It's not uncommon for us to find melted insulation, damaged splices among other things, that's actually one of our companies specialties, lightning damage testing and repair.

Any structure that received a lightning hit needs to be inspected by a qualified contractor with the proper test equipment.

No one should be under any allusions that a ground rod or two will make their house lightning proof, we even repair damage in facilities with full engineered LPS, lightning does what it wants.

 

[sberry]

Also take a look at 880 and ground the phone. Lots of strikes carried in on phone lines. The installers don't always do it right.

 

[Alan Douglas]

Ground rods are really just installed because the code says we have to, they serve little purpose

I tend to agree. A little math: assume the allowed 25 ohms, and a lightning strike of 10,000 Amperes. That's 250,000 Volts that your electrical system is, above ground (or anything grounded, such as the phone line).

 

[sberry]

The grounding allows for a pathway for any added protection. I had issues, grounded the phones well and a big strike took out the phonco protection like it should vs passing it thru to a cheap power strip, got a whole box of those blown buggers and not 1 since I fixed it and havnt rushed to disconnect at the hint of a storm since.
Things are somewhat better these days as modems are now often external vs being placed in a grounded chassis. If the phone wasn't grounded the next best place was the puter.
There was a lot of surge sold, it really didn't fix a problem but hide one by still inviting a strike in.

 

[CNGsaves]

Lot of bad advice from JLarson in Arizona that likely has just couple rain storms a year and virtually no lightning. NOT representative of rest of world.

Do It Right, Do It Once and put in the two 8 ft ground rods using 6 gauge wire and put the rods out in proper soil (this assuming no UFER ground installed in slab/footing concrete). The pre-cast concrete access cover for $26 is cat's meow and great idea.

 

[wyliesdiesels]

Just because there wasn't any damage to any appliances doesn't mean they isn't concealed damage to conductors and splices. It's not uncommon for us to find melted insulation, damaged splices among other things, that's actually one of our companies specialties, lightning damage testing and repair.

Any structure that received a lightning hit needs to be inspected by a qualified contractor with the proper test equipment.

No one should be under any allusions that a ground rod or two will make their house lightning proof, we even repair damage in facilities with full engineered LPS systems, lightning does what it wants.

I do Motorola R56 grounding for a living. Many of our communication towers have nothing more than grounding electrodes as well as halos. For the radios we install inline lightning arrestors and thats it. Many of our towers have been hit by lightning several times and none of them have had any issues, fried equipment, etc.

What exactly are u installing that youre calling LPS?

 

[sberry]

Nothing he said was "bad" advice.

 

[Jlarson]

What exactly are u installing that youre calling LPS?

Air terminals, down conductors, ground rings or grids, sometimes chemical electrodes based on soil, complete bonding of all metal equipment and utilities. Followed by full multi-level TVSS protection on all power, instrumentation and comm lines.

Proper bonding of everything together to one common ground point is really the most important part, that's one of the reasons transmitter sites do so well. If you can get everything to the same potential during a strike the equipment has a far better chance.

We do municipal and industrial, treatment plants, chemical and manufacturing plants along with building their SCADA infrastructure. I've done one or two electrode systems along the way.


But we are talking basic resi electrical service here, 2 ground rods is an exercise in wasting time and material. It's a requirement that many electricians would like to see removed from the NEC.

Well I guess its good physical exercise if you still pound them in with a sledge.

 

[sberry]

There is a lot of debate about it is right and a lot of it is from people way above or pay grade.

 

[sberry]

I remember Keis on another forum discussing some of it. He had a really good simple explanation. He used parking lot lights as an example. It must have grounding conductor for fault but they often added another rod at the poles in hopes or with the general theory that they would like the strike to dissipate there vs following the service conductors back to the panel.
I was having some issues and the well man didn't seem to know much but I finally got it when he instructed me to ignore the rods and use a lug to the steel well casing.

 

[sberry]

I saw one recently where they assumed lighning had hit the well,,, it did terminate there via the conductor ground to the motor chassis. It did not have a wire from the service to the casing like it should have. Carried it downhole to the motor thru the riser vs the casing.

 

[sberry]

As the man said, other facilities with rings and multiple electrodes are different to some extent. Most strikes are not to the incoming power but the facility itself, similar to TV antennas, reading the code here might give a little insight.

 

[wyliesdiesels]

Air terminals, down conductors, ground rings or grids, sometimes chemical electrodes based on soil, complete bonding of all metal equipment and utilities. Followed by full multi-level TVSS protection on all power, instrumentation and comm lines.

Proper bonding of everything together to one common ground point is really the most important part, that's one of the reasons transmitter sites do so well. If you can get everything to the same potential during a strike the equipment has a far better chance.

We do municipal and industrial, treatment plants, chemical and manufacturing plants along with building their SCADA infrastructure. I've done one or two electrode systems along the way.


But we are talking basic resi electrical service here, 2 ground rods is an exercise in wasting time and material. It's a requirement that many electricians would like to see removed from the NEC.

Well I guess its good physical exercise if you still pound them in with a sledge.

If lightning strikes the pole nearby or something on house, u want grounding electrodes on your electrical service so the lightening has a place to go.

Grounding electrodes are also for limiting the voltage to ground...

 

[Jlarson]

I'm not saying you shouldn't have a GES but rods are just a poor way to go about it.

In basic resi and commercial construction a CEE is the best you are going to get without spending a ton of money.