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06-16-2012, 10:29 AM
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#1
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Electron Flow Consultant
Join Date: Mar 2008
Location: Longview, WA
Posts: 2,086
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30' ground rods
We are starting the grounding grid on a new substation and the spec 30' of ground rods. We are to drive 10' rods and cad weld additional rods. Anyone ever have to do this?
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06-16-2012, 10:42 AM
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#2
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crispy critter
Join Date: Oct 2011
Location: west coast 45th parallel
Posts: 1,556
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Quote:
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Originally Posted by sparky970
We are starting the grounding grid on a new substation and the spec 30' of ground rods. We are to drive 10' rods and cad weld additional rods. Anyone ever have to do this?
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What do you mean by cadweld additional rods? you mean cadweld the rods together?
__________________
I'm old enough to know better, but too young to care.
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06-16-2012, 11:09 AM
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#3
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Not here at the moment
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Spec'd out because that's what the last guy spec'd out.
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06-16-2012, 11:11 AM
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#4
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Not here at the moment
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Wait, 30' of ground rods, or 30' ground rods?
30' of rods is (3) 10' in a delta config.
30' ground rods sound pretty stupid
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06-16-2012, 11:14 AM
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#5
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Moderator
Join Date: May 2009
Location: Chapel Hill, NC
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They make ground rods that are screwed together to make unlimited lengths. Called Sectional Ground Rods
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Last edited by Dennis Alwon; 06-16-2012 at 11:20 AM.
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06-16-2012, 11:18 AM
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#6
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Who you gonna call?
Join Date: Feb 2012
Location: iowa
Posts: 712
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30' ground rods seem to be the new fad in grounding voodoo. I've had to drive them before to help suppress voltage spikes according to the engineer. It didn't work.
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06-16-2012, 11:21 AM
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#7
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Moderator
Join Date: May 2009
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The concept is more surface area in contact with the earth and there is more likely to be water or soil that has more moisture down deeper in the earth.
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06-16-2012, 11:25 AM
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#8
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Not here at the moment
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Quote:
Originally Posted by Dennis Alwon
The concept is more surface area in contact with the earth and there is more likely to be water or soil that has more moisture down deeper in the earth.
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Use plates.
I can't see a 30' rod going in around here without drilling the rock first.
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06-16-2012, 11:28 AM
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#9
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Moderator
Join Date: May 2009
Location: Chapel Hill, NC
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Quote:
Originally Posted by Dnkldorf
Use plates.
I can't see a 30' rod going in around here without drilling the rock first.
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Obviously they are not worth it in some areas. IMO, a CEE is a great electrode. I have mentioned it many times that I had 2 rods giving me about 89 ohms and on the same property I installed a CEE that had 13 ohms. No brainer for me.
Unfortunately for some data and communication buildings this is not enough.
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06-16-2012, 11:37 AM
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#10
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Electron Flow Consultant
Join Date: Mar 2008
Location: Longview, WA
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Quote:
Originally Posted by Dennis Alwon
They make ground rods that are screwed together to make unlimited lengths. Called Sectional Ground Rods
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It would be just like those, but welded end to end.
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06-16-2012, 12:06 PM
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#11
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Senior Member
Join Date: May 2009
Location: CA
Posts: 343
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Quote:
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Originally Posted by sparky970
It would be just like those, but welded end to end.
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Why would you weld ground grounds. I do not even think you can weld them, as least not cadwelding them.
I've driven 20-40' ground rods before and we have only used ground couplings.
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06-16-2012, 12:07 PM
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#12
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Not only does it sound like a pain in the ass, I also think those welds would quickly fail.
It really sounds like someone misunderstood a spec. that said that multiple rods had to be cad-welded together--meaning joined by a cadwelded conductor--and assumed it to mean the rods themselves had to be connected.
-John
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06-16-2012, 12:09 PM
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#13
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Moderator
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Quote:
Originally Posted by Big John
Not only does it sound like a pain in the ass, I also think those welds would quickly fail.
It really sounds like someone misunderstood a spec. that said that multiple rods had to be cad-welded together--meaning joined by a cadwelded conductor--and assumed it to mean the rods themselves had to be connected.
-John
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That makes sense. Cadweld the conductor to the rod but not cadwell the rods together
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06-16-2012, 01:07 PM
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#14
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Electron Flow Consultant
Join Date: Mar 2008
Location: Longview, WA
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Quote:
Originally Posted by Big John
Not only does it sound like a pain in the ass, I also think those welds would quickly fail.
It really sounds like someone misunderstood a spec. that said that multiple rods had to be cad-welded together--meaning joined by a cadwelded conductor--and assumed it to mean the rods themselves had to be connected.
-John
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It specifically states to drive ground rods to a depth of 30' and to use exothermic welding to splice ground rods. It is also shown in the details as well as the Cad mold part number and shots to use in the BOM. That would be pretty hard to misunderstand.
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06-16-2012, 01:11 PM
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#15
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Senior Member
Join Date: May 2009
Location: CA
Posts: 343
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Quote:
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Originally Posted by sparky970
It specifically states to drive ground rods to a depth of 30' and to use exothermic welding to splice ground rods. It is also shown in the details as well as the Cad mold part number and shots to use in the BOM. That would be pretty hard to misunderstand.
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That is beyond stupid considering that when you start driving it down, you will be hammering the ground rod against the Caldwell an if done enough times there is a chance for it to break. I would RFI it and ask to use the coupling method. It will save you in time and labor.
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06-16-2012, 01:28 PM
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#16
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Electron Flow Consultant
Join Date: Mar 2008
Location: Longview, WA
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The utilities around here are very specific about how they want things done, so that won't happen. It was bid accordingly and we already have the material. We only have to do 27 of them.
Last edited by sparky970; 06-16-2012 at 01:32 PM.
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06-16-2012, 01:35 PM
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#17
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Senior Member
Join Date: Nov 2010
Location: New England
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Quote:
Originally Posted by qckrun
I do not even think you can weld them, as least not cadwelding them.
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They are just copper coated steel, of course you can cadweld them.
Quote:
Originally Posted by Big John
Not only does it sound like a pain in the ass, I also think those welds would quickly fail.
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If the cad weld is done correctly it will last longer than the rods.
But I also think a 30' rod is nuts.
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06-16-2012, 01:37 PM
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#18
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1,000,000th Poster
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Location: Portland
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Quote:
Originally Posted by sparky970
It specifically states to drive ground rods to a depth of 30' and to use exothermic welding to splice ground rods. It is also shown in the details as well as the Cad mold part number and shots to use in the BOM. That would be pretty hard to misunderstand.
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I didn't mean you, I mean the person who wrote the specs. They may have seen some boilerplate somewhere that said "connect 3 ground rods" and this is how they interpreted it.
Quote:
Originally Posted by BBQ
...If the cad weld is done correctly it will last longer than the rods...
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I don't argue that it should, I'm just thinking of how many bad welds I've seen that aren't also being hit with a hammer. Add in trying to get a solid weld while lining up one 10' rod exactly parallel with the other.
-John
Last edited by Big John; 06-16-2012 at 01:41 PM.
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06-16-2012, 01:51 PM
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#19
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Electron Flow Consultant
Join Date: Mar 2008
Location: Longview, WA
Posts: 2,086
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Quote:
Originally Posted by Big John
I didn't mean you, I mean the person who wrote the specs. They may have seen some boilerplate somewhere that said "connect 3 ground rods" and this is how they interpreted it.
-John
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Engineers don't make mistakes 
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06-16-2012, 01:54 PM
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#20
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Senior Member
Join Date: Nov 2010
Location: New England
Posts: 23,768
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Quote:
Originally Posted by Big John
Add in trying to get a solid weld while lining up one 10' rod exactly parallel with the other.
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You lost me  , if you were cad welding it the mold would hold the two rods in aliment albeit not perfectly straight but neither would a threaded coupling.
As a side note they cad weld train tracks together. 
These guys seem like some safety training could help.
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