Mike Honcho
Well-known member
Is there a maximum distance that the ground rods can be away from a subpanel? And can they be covered in concrete once installed or do they have to be accesible. Thanks in advance.
Chris
Chris
Ground rods
- Thread starter Mike Honcho
- Start date
Aceman
Well-known member
No maximum and they can be covered by concrete after inspection.
OP
Mike Honcho
Well-known member
thank you sir
sberry
Banned
Only issue is if it becomes so dry under crete? Its just a personal thing but I try to get them under an eve where there is water run off.
Stevie-Ray
Well-known member
You should leave them exposed, as the clamps are known to break within a few years. I've replaced one on my house, not known how long it's been broke, but the house was built in '99.
Zeke
Well-known member
I think I'd can them out meaning placing a sleeve around them. You can put a clean out cap in a threaded fitting to cover. Be sure the rods have good earth contact but you could spread out 4 or so inches of gravel around the rod top and out a bit to ensure water doesn't collect in your 'can.'
I just don't like things that are buried and you can't see when a connection is involved.
I just don't like things that are buried and you can't see when a connection is involved.
sberry
Banned
Biggest thing that I gained when I went back and poured over the code was for the phones. I am not real bright so I ask my engineer type,,, why does it take out the modem and not other devices,, he says,, the other phones are 2 wire, the computer is grounded to the electric,, duh.
It would be helpful if the phone guys read the electric code, I ran a wire one size bigger and grounded to the electric system and not one problem since, not one surge protector which was on going if I didn't run and unplug comp line and the only strike that did come down blew the protector proper like it should at the entrance.
I got a super uffer but no good unless its connected,, ha
I had to dewater a corner for a loading dock when I poured the footer, all the resteel is bonded and I pounded a rod 10 ft into standing water. I don't imagine it gets much better than a bunch of rebar bonded together with welds sitting in and under 10 ft of cement and several feet of dirt with a couple rods pounded down thru that 10 ft.
It would be helpful if the phone guys read the electric code, I ran a wire one size bigger and grounded to the electric system and not one problem since, not one surge protector which was on going if I didn't run and unplug comp line and the only strike that did come down blew the protector proper like it should at the entrance.
I got a super uffer but no good unless its connected,, ha
I had to dewater a corner for a loading dock when I poured the footer, all the resteel is bonded and I pounded a rod 10 ft into standing water. I don't imagine it gets much better than a bunch of rebar bonded together with welds sitting in and under 10 ft of cement and several feet of dirt with a couple rods pounded down thru that 10 ft.
Last edited:
For human safety, the ground should not be more than twenty feet away. For transistor safety, even ten feet is too far.
As others noted, clamps should be available for inspection. Furthermore, concrete in contact with copper wire can break down that copper.
One solution is to place a six inch plastic pipe vertically around the rod and clamp. Then clamps can be inspected. Wires tested for conductivity. And a cap protects that from damage. We located all that so that the cap was flush with concrete - did not trip humans.
Earthing for human safety need only meet code. Earthing to protect transistors demands many installation rules that exceed code requirements.
BTW, these rules are even more critical on the main panel.
Is it too late to install superior earthing? ie Ufer ground?
OP
Mike Honcho
Well-known member
Dragging this back up. I finally got around to starting my concrete, and i "canned" the ground rods and ran a stick of conduit between them so i can run the wire at a later date. is this kosher or does the wire itself need to be in contact with the earth as well? thanks
Chris
If conduit is metallic, then a ground wire has increased impedances; becomes non-conductive to surges.
Best earth ground is an Ufer ground. That is wire embedded in concrete. However concrete will 'eat' copper with age. Meaning you probably want copper that is twice as thick (maybe 6 AWG sizes larger).
Being able to inspect the earthing connection is desireable. But also learn about best earth grounds - Ufer grounds. One demonstrated how he did this in: http://scott-inc.com/html/ufer.htm
Another relevant discussion here:
http://lists.contesting.com/archives//html/Towertalk/1999-09/msg00141.html
And here:
http://www.mikeholt.com/mojonewsarchive/GB-HTML/HTML/UferGroundPsi~20030930.htm
rockwithjason
Well-known member
Mostly from over 100 years of science and experience. Much can be gleemed from IEEE papers. Earthing for human safety is defined by code. Earthing for transistor safety involved concepts often not even known by electricians. For example, code addresses wire thickness for lower resistance. Earthing for other functions involves shorter length (not thickness) for lower mpedance.
A case study demonstrates how proper earthing improves protection:
http://www.copper.org/applications/electrical/pq/casestudy/nebraska.html
A tech note demonstrates principles including that same risk applies to both overhead and underground wires:
http://www.erico.com/public/library/fep/technotes/tncr002.pdf
To better understand requires concepts taught in a field course. How these electrical concepts are achieved were summarized by examples. Appreciate that earthing is an 'art'. Also learned from human created mistakes. Tracing a destructive surge path to often learn what was overlooked. Since materials including concrete, linoleum tile, and wood are electrical conductors to this electricity. More examples of the 'art'.
sberry
Banned
If this pour isn't done yet there needs to be a uffer from the rods in the foundation. It is something I would absolutely take a picture or 2 of before cement went down in case someone gets a hair up their azz after the fact.
theoldwizard1
Well-known member
All "modems" (cable, U-Verse, DSL, etc) have an isolation transformer inside.
OP
Mike Honcho
Well-known member
This isnt a pour for a garage, my ground rods for my sub panel ended up where i want to put my patio. so i put 4 inch pvc pipes around the ground rods leaving access to to view the rod, wire and acorn clamp, and connected the two with 3/4 conduit so i can replace the wire if need be.
kaffine
Well-known member
Motorola R56 is a good read for grounding. Good read as in it has a lot of info not that it is exciting. I know a few companies that just use Motorola standards instead of coming up with their own when it comes to grounding.
sberry
Banned
Art 880 I believe for phones, since I re did mine havnt blown a single piece of equipment, no more sure suppressors, 1 strike took out the phone co side like it was sposed to.
SportFury59
Well-known member
I believe the Ufer system became code in 2008. That's when I built my garage and the inspector informed me and the concrete guy about this. Concrete guy never heard of Ufer and resisted/protested. I guess he didn't like change.
Anyway, out of curiosity............ if this was developed during WWII and the Radio Station article was written in 1989, and this system has so many advantages, why did it take so long for this to become code.
My ground rod/rebar protrudes from concrete between studs. When installing drywall I guess it would be a good idea to have a access panel there.
JohnX14
Well-known member
Keep in mind that a concrete encased electrode is commonly referred to as a "Ufer" ground. While it is similar, a true ufer ground is much different than a simple rebar or bare conductor encased in concrete. And it still is not "required". It is only "required" if there is steel available in the foundation or footing. Around here most houses do not have any rebar. For my builders that are organized, I install 20' of #4 in the footing by choice.
sberry
Banned
I wasn't real familiar with codes when I put my building in but ll the rods are connected and bonded to the steel and my loading dock footer is sitting in standing water, its a super uffer and at the time I pounded a rod or 2 down there and bonded it to the steel.
The phone co doesn't read art 880 very well and in some places they manage to get it to the electric rods and on occasion pound a rod with the deer in the headlights look followed by,,, I don't understand why. I don't recall now what they had on my entrance, maybe a rod, maybe nothing but I run it to my rods and uffer and ended my lightening strike problems.
Agreed, probably not a true uffer.
The phone co doesn't read art 880 very well and in some places they manage to get it to the electric rods and on occasion pound a rod with the deer in the headlights look followed by,,, I don't understand why. I don't recall now what they had on my entrance, maybe a rod, maybe nothing but I run it to my rods and uffer and ended my lightening strike problems.
Agreed, probably not a true uffer.
Last edited:
jkwilson
Well-known member
Noticed the reference to "pounding" ground rods. Though soil conditions vary, you can put a 10ft ground rod in the ground without breaking a sweat using a glass of water. No hammer required.
I have very hard clay soil and it would be exhausting to drive one with a hammer, but this way is fast and easy.
I have very hard clay soil and it would be exhausting to drive one with a hammer, but this way is fast and easy.
porschedude996TT
Well-known member
FYI,
Wiki states during WW2 in 1942 Herbert G. Ufer came up with a grounding system for a bomb storage facility in Arizona which is very dry. After the war it was published in a paper at an IEEE conference and then adopted in the NEC in 1968. Time line seems normal to me...LOL
http://en.wikipedia.org/wiki/Ufer_ground
Wiki states during WW2 in 1942 Herbert G. Ufer came up with a grounding system for a bomb storage facility in Arizona which is very dry. After the war it was published in a paper at an IEEE conference and then adopted in the NEC in 1968. Time line seems normal to me...LOL
http://en.wikipedia.org/wiki/Ufer_ground
alfredeneuman
Well-known member
The original Ufer test was 18 years which lasted until 1960. It was in Tucson. Rebar was used as the electrode.
It performed so well that he went to Flagstaff (with different soil characteristics) and placed a piece of copper wire in the footing of a building. It performed even better.
It performed so well that he went to Flagstaff (with different soil characteristics) and placed a piece of copper wire in the footing of a building. It performed even better.
OP
Mike Honcho
Well-known member
so after all this, the garage is considered attached. is it worth while to run a wire to the ground rods, or is it against code since it is attached?
Charles (in GA)
Well-known member
Ufer only works if the concrete is in DIRECT CONTACT with the earth. Most slabs are poured with a layer of gravel and then plastic under them and up the sides sometimes. If you use plastic under a slab, you probably should drive ground rods.
Charles
Charles
wyliesdiesels
Well-known member
Grounding electrodes arent needed for an attached structure because theres already groundig electrodes(or should be) at the main service panel...not against code but not needed and waste of money.
Posted was a relevant concept:
A ballpark guideline says if structures are separated more than 20 feet, then each should be single point grounded where an interconnecting wire enters both structures. An example of earthing that must exceed code requirements.
wyliesdiesels
Well-known member
What country are u from? Where do u come up with your statements? SMH Are u familiar with R56 grounding?
Basic electrical knowledge demonstrates a ground wire, sufficient to meet code, can also be insufficient for surge protection.
Earthing to protect transistors involves electrical concepts irrelevant to earthing for human safety. Transistor protection is about both conductivity and equipotential. A wire of low resistance can also have excessive impedance. Examples of why earthing for human safety may also be woefully insufficient for transistor safety. These relevant electrical concepts exist in every nation in the world.
If familar with basic electrical concepts demonstrated by Motorola's R56 Standard, then one would know why each structure may need its own ground. Why each connection to earth must be so short (ie 'less than 3 meters'). And why that earthing for each structure must be single point. Why do you not know these well understood principles?
LS6 Tommy
Well-known member
Never happen with the ground around me. It's also a good way to end up with a lousy ground...
Tommy
Charles (in GA)
Well-known member
Hammer drill works wonders on a ground rod.
Charles
Charles
James-W
Well-known member
When I built my garage I had asked the electrician where to put the ground rods and he said that it was best to put them close to the building and put plastic bottles over the rods and the clamps. So when the grounding rods were in the ground, I cut the bottoms off two plastic bottles (I left the caps on the bottles) and put them over the rods and the clamps. The rods are under the ground with just the bottle caps sticking up a little ways. If I need to, I can move a little dirt out of the way and look thru the plastic bottles to see if the clamps are still on tight.
zmaxmotorsports
Well-known member
I found a cat 307 mini ex to be really handy for for pushing rods through the frost in minot nd years ago when I worked up there!
Coyote556
Well-known member
I welded a spark plug socket to an air chisel and used that on my air hammer to drive the ground rods.
wyliesdiesels
Well-known member
Thats a clever idea!
toplessHO
Well-known member
the only way I would bury a ground rod that has mechanical connection is to have an access well. If you must bury it get someone to cadweld it and cover connection with tar.
Roof patch works fine.
Roof patch works fine.