Ufer ground connection installation
- Thread starter elecmen
- Start date
- Status
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Yes GEC's can be buried, if not you may have a hard time connecting them to ground rods. Also the burial depths in T300.5 do not apply to GEC's. Does the monolithic slab qualify as an electrode?
- Location
- New Jersey
- Occupation
- Journeyman Electrician
It could be bare or insulated, stranded or solid, any color too. We always use #6 THHN/THWN stranded for ground rods.
What I have done to save money on a ufer ground is stub up a piece or rebar underneath were the panel is going to go. I then also stub up a piece of rebar 25 feet away for a reference if the inspector wants to check the resistance. Then I put a acorn with #4 on the rebar with a 2 gang mud ring for access and call it good.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Just curious as to why an inspector would want to check the resistance of a CEE?
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Really, local code very interesting. How exactly would they test it?
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
Well, first you have to also provide him another ground with less than 1 ohm resistance to use as a reference.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
I realize this is a local code but this is not the intention of NEC. Only made elecrodes which would be rod or pipe electrodes (not underground water pipe either) need to meet the 25 ohm requirement. Even if they don't meet 25 ohms, NEC only says you need to provide one more electrode. If still not 25 ohms or less they don't require anything else.
What does WAC require should a CEE not meet the 25 ohm rule? You have to tear out the footings and start over? Maybe adding some salt to the surroundings to make things more conductive - and more corrosive to the metal used in the CEE:roll:
Somebody doesn't get it, yet all the contractors and engineers that work the area still let them continue with their ignorance apparently.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
I would be very surprised to find a compliant CEE with a resistance as high as 25 ohms. The real problem, as stated, is how to measure it. The fall of potential method is hard to apply to such a large electrode, and a clamp test presumes the existence of a comparable or better set of electrodes for current injection.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
In another thread the OP described an area where the inspector would not look at the connection and rebar pre-pour but required two wires to be brought out at least 20' apart so all he had to do was check continuity between them.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
I thought of commenting earlier that this may just be to do a simple check for continuity between the two points. The next question that would bring up is what kind of reading is considered go/no go? A NEC compliant CEE could be multiple pieces of rebar in concrete connected together only by tie wires. In that kind of instance I would expect continuity but not necessarily extremely low resistance like you would get if you had both ends of a single 25 foot piece of rebar stubbed out of the footing.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
I would hope less than one ohm.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Seems logical it would be, but go to a pretty dry location, a new footing probably is low resistance as there is still moisture in the fresh concrete, but one that has been there for some time may not be quite as low resistance, though that kind of gets off track of an inspection of a new CEE anyway.
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