mebedave
Well-known member
What do the pro’s do when you start to drive ground rod and hit rock at 2 foot. Here in Kansas we have a lot of lime stone. My layer of lime stone is about 5 feet thick. What would you do??
ground rod hit rock need advise
- Thread starter mebedave
- Start date
nehog
Well-known member
Let's say you try a few locations and all are hitting bedrock. The next thing to do is use a ground plate or plane. That will be a large piece of metal that is buried as deep as you can get it. Some are made of soldered/welded bar, some are plates with holes punched in them.
Falcon67
Well-known member
If you have rebar in your slab, you can find a spot to punch in and tie on to the rebar for a UFER ground. It's rough but doable.
chickenhauler
Well-known member
All I have is rock around my shop. Had I known ahead of time that I could have put the rods in my footer, I would have. I ended up laying mine in little trenches then covering them up. Who knows how much "grounding" a rod is going to do in a pile of sandstone, but the inspector was happy with it.
The_Tango
Active member
Drive it in at an angle, say 30 degrees off vertical - Sometime that will allow it to veer off if it contacts something
Like mentioned, try again at an angle or just bury a ground plate instead of a rod. Doesn't need to be nearly as deep. Check your laws though as I'm sure ours are different up here in Canada.
What are you using to install the rod? A big hammer drill and a cup attachment or the clamp on attachment is preferable and you'd be surprised at what you could put a rod through with one of those.
Also for anyone else, if the ground is frozen try "lubricating" the rod with some antifreeze. They drive like butter then.
What are you using to install the rod? A big hammer drill and a cup attachment or the clamp on attachment is preferable and you'd be surprised at what you could put a rod through with one of those.
Also for anyone else, if the ground is frozen try "lubricating" the rod with some antifreeze. They drive like butter then.
When I built the ufer had to be inspected and tagged before pouring the concrete so check with the inspector. That said, where are you in the building process? You have the option of a ufer ground, laying the ground rod in a trench, and as others have said a ground plate. I would suggest talking with the building inspector and ask what to do as I'm sure that others in the area have had to deal with the same issue.
lg
no neat sig line
rwreuter
Well-known member
the building inspector isn't the person that has to buy off on it...it is the electrical inspector.
in accordance with the NEC you can drive the ground(S) (2) up to a 45 degree angle (6' apart)
the pros (larger contractors) have Hilte's that drive the rods down into the ground. first we try to drive them in vertical and if that doesn't work then up to 45 degrees. that usually works. you can rent these from rent-a centers or Lowes or Home Depot.
word of caution..if you use a Hilte, put the DB (direct burial) clamp on first...the Hilte will mushroom the ground rod and you won't be able to get the clamp on.
concerning that plate, i have never seen one installed (of course that is not to say that it isn't done. when i built my house i drove 2 ground rods and used a ufer ground also.
in accordance with the NEC you can drive the ground(S) (2) up to a 45 degree angle (6' apart)
the pros (larger contractors) have Hilte's that drive the rods down into the ground. first we try to drive them in vertical and if that doesn't work then up to 45 degrees. that usually works. you can rent these from rent-a centers or Lowes or Home Depot.
word of caution..if you use a Hilte, put the DB (direct burial) clamp on first...the Hilte will mushroom the ground rod and you won't be able to get the clamp on.
concerning that plate, i have never seen one installed (of course that is not to say that it isn't done. when i built my house i drove 2 ground rods and used a ufer ground also.
To late for ufer ground, slab is in already. although my jib crane could be used as a ufer ground i guess. The footing for the jib sets on the rock layer which I drilled and drove lots of rebar into the rock and the anchor bolts for the jib are welded to the rebar. Only problem here is the jib would be about 20' from the panel. would that work?? I can try to drive at a 45 degree, but I know for a fact the rod will hit rock at about 2 foot will that be deep enough if i can get the rod driven at a 45. Question if you have a ground rod or two why and what is a ufer (i know its rebar from your footing but why)
Falcon67
Well-known member
>To late for ufer ground, slab is in already.
Just for fun - In the large city close to here, the inspectors will MAKE you jackhammer into the slab if there is no rebar sticking out for a UFER. There is no "too late for that". In fact, that city requires TWO methods, one of which must be a UFER.
UFER is a grounding system discovered around WWII. Concrete is conductive, so your slab and rebar sitting on the ground is one big fat ground connection. I used 20' of #4 copper in the slab.
Just for fun - In the large city close to here, the inspectors will MAKE you jackhammer into the slab if there is no rebar sticking out for a UFER. There is no "too late for that". In fact, that city requires TWO methods, one of which must be a UFER.
UFER is a grounding system discovered around WWII. Concrete is conductive, so your slab and rebar sitting on the ground is one big fat ground connection. I used 20' of #4 copper in the slab.
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it always irks me that inspectors are constantly missing the fact that ufer ground is not optional. If you have a footer with rebar in it, you HAVE to bond the rebar...(on new construction, and inspector has to sign off on it before the pour
Falcon67
Well-known member
Hmmm - comments because that seems to not be the way 2011 reads. See #3, what I based my one electrode on (#3, sub 2):
"
250.52 Grounding Electrode Types.
(A) Electrodes Permitted for Grounding.
(1) Underground Metal Water Pipe Electrode. Underground metal water pipe in direct contact with the earth for 10 ft or more can serve as a grounding electrode.
(2) Metal Frame Electrode. The metal frame of a building/structure can serve as a grounding electrode when it meets at least one of the following conditions:
(1) At least one structural metal member is in direct contact with the earth for 10 ft or more, with or without concrete encasement.
(2) The bolts securing the structural steel column are connected to a concrete encased electrode [250.52(A)(3)] by welding, exothermic welding, steel tie wires, or other approved means.
(3) Concrete-Encased Electrode. At least 20 ft of either (1) or (2):
(1) One or more of bare, zinc-galvanized, or otherwise electrically conductive steel reinforcing bars of not less than ½ in. diameter, mechanically connected together by steel tie wires, welding, or other effective means, to create a 20 ft or greater length.
(2) Bare copper conductor not smaller than 4 AWG.
The reinforcing bars or bare copper conductor must be encased by at least 2 in. of concrete located horizontally near the bottom of a concrete footing or vertically within a concrete foundation that’s in direct contact with the earth.
If multiple concrete-encased electrodes are present at a building/structure, only one is required to serve as a grounding electrode"
Note: Concrete containing insulation, vapor barriers, films or similar items separating it from the earth isn’t considered to be in “direct contact” with the earth.
Remainder for the OP's problem:
(4) Ground Ring Electrode. A ground ring consisting of at least 20 ft of bare copper conductor not smaller than 2 AWG buried in the earth encircling a building/structure can serve as a grounding electrode.
(5) Ground Rod and Pipe Electrode. Ground rod electrodes must not be less than 8 ft in length in contact with the earth [250.53(G)].
(b) Rod-type electrodes must have a diameter of at least 5⁄8 in., unless listed.
(6) Listed Electrode. Other listed grounding electrodes.
(7) Ground Plate Electrode. A bare or conductively coated iron or steel plate with not less than ¼ in. of thickness, or a solid uncoated copper metal plate not less than 0.06 in. of thickness, with an exposed surface area of not less than 2 sq ft.
(8) Metal Underground Systems Electrode. Metal underground piping systems, underground tanks, and underground metal well casings can serve as a grounding electrode.
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rwreuter
Well-known member
(2) Metal Frame Electrode. The metal frame of a building/structure can serve as a grounding electrode when it meets at least one of the following conditions:
notice the conditions that need to be met to be forced to use a ufer....metal frame building.
notice the conditions that need to be met to be forced to use a ufer....metal frame building.
rwreuter
Well-known member
see a ufer ground set up is supposed to be inspected BEFORE the concrete is poured to insure that a minium number of feet are tied together.
so if the inspector forces you to jack hammer and us a ufer ground he may be costing you a lot of money for no reason. the rebar may not be all be tied together PROPERLY.
so if the inspector forces you to jack hammer and us a ufer ground he may be costing you a lot of money for no reason. the rebar may not be all be tied together PROPERLY.
rwreuter
Well-known member
distance is irrelavent....when you bond your water pipe and gas pipe i have often had to run clean across the house and into the under floor in order to get to within 10' of the entrance.
2' feet will not be deep enough....i guess you could dig a large ditch like someone else said and lay the rods out, as long as they are more than 6' feet apart i guess that would work. as a last resort, what i have done when i come to a serious problem area, i just call the inspector and explain the situation and let him make a recommendation. they usually are very helpful.
they will have an answer, because i can gurantee you that this isn't the only situation that has come up in your area.
HOTFR8
Banned
I have a spike in the ground but further to that the Electrician added a long cable from the spike into a trench.
rwreuter
Well-known member
not sure about that, just call the electrical inspector.....let him know what is going on....i didn't know it was a metal building...according the 2011 NEC you will have to have a ufer ground (that is of course if your AHJ has adopted the new code.
call him/her and let them know what the situation is....they will work with home owners much better than an electrical contractor.
call him/her and let them know what the situation is....they will work with home owners much better than an electrical contractor.
sberry
Banned
Seeing on it sounds like an inspector may be absent here run a number 4 to the footer steel of your crane, in all reality its probably as good as it gets. Well casing if I had it nearby or had steel water piping if possible.
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planecrazy29
Well-known member
- Joined
- Oct 10, 2011
- Messages
- 72
I believe you have to ground it. I'm not an electrician, but I work in an industry where we have had people get killed because metal buildings and/or siding was not grounded. If it's not grounded and it made hot somehow, you become the ground when you touch the metal. Even if it's not required, please ground it.