I was always led to believe that embedding bare copper in concrete was bad because the concrete would chemically breakdown the copper.

I would be more comfortable with using two grounding rods, 10-ft long, cadwelded together set on spacers and laid at the bottom elevation of the footing, but not in the footing. Dig a trench to lay the ground rods in and pour some concrete around it. This way, the concrete in the footing would not be exposed to vaporization from heat generated by the lightning strike. Cadweld a #4/0 or larger bare copper cable to the ground rod and bring up to the surface in a PVC conduit for protection. From the surface it can then be extended to the electrical service grounding bars.

Any comments?

tHIS SHOULD BE REQUIRED READING FOR ALL COPPER THIEVES.

Apparent copper thief gets severe shock

08:57 PM CST on Wednesday, February 27, 2008

By JESSICA VESS KVUE News

Witnesses describe how a copper thief caused a major power outage in East Austin Wednesday afternoon. Over 7,000 people were without electricity for more than two hours, and authorities say the thief was air lifted to the hospital with severe electrical burns over his entire body.

The man was inside the Kingsbury substation. 138,000 volts flow through that substation. There are only 10 substations that large in the entire city. It's fenced in and the gates are locked. Warning signs are posted all around it indicating the threat of a severe electric shock from the equipment could kill someone.

Wednesday afternoon Austin Energy officials say it appears that the man cut through the fence in several spots and then went inside, apparently attempting to cut out copper wire that connects the station to the ground.

“I heard something pop and everything like that and I came from the creek,” said witness Jesse Hernandez.

When Hernandez came up he saw a man still stuck inside the fence of the sub-station. The man was engulfed in flames, 100% of his body was burned.

“I was telling him to stop and roll around in the grass but he was already burnt up,” said Hernandez.

Others nearby rushed out too after the loud pops. The electric shock that caught the man on fire also cut off power to 7,300 homes. Most people wanted to see what caused the noise, but nobody expected to see a man on fire.

“It was scary because like we heard those two big breakers pop and we went outside and we just saw him back there running like crazy. His whole clothes were on fire. You could see the flames on him. After all we just seen back there and his clothes, I mean his skin was just coming off,” said witness Ricardo Rodriguez.

The man was taken by STAR flight to Brackenridge Hospital. He was then transported to Brooke Army Medical Center in San Antonio. He has burns over his full body and is in extremely critical condition. Austin Energy officials estimate he was shocked with 80,000 volts of electricity.

Austin Energy crews inspected the substation and found multiple equipment grounds missing. Those wires are there so that a power surge caused by lightening or failure will flow into the ground rather than into the equipment. Crews also noticed that the surge may have damaged the equipment too. Crews had to pull new wires and had power restored in about two hours.

Austin energy officials say they've seen an increase in copper thefts at substations like the one on Kingsbury as well as power poles and transmission towers. In South Texas a man died trying to remove copper wiring from similar equipment. It's still unclear what this man's condition is or what charges he may face. Austin Energy says it is increasing surveillance around its substations.

in many of our potential transformer the yellow phase is connected to earth and the neutral left insulated why?

How can the NEC accept 'wire ties' to maintain continuity of the 20 foot rebar requirement (eg made up of 5 4-foot sections), yet require a 'listed' connector to bond the copper conductor to the rebar grounding electrode?

Ufer, intersesting name. Anyway, one reason to get away from connected to the plumbing is that in cases where copper pipe joins steel pipe a galvanic union is always, must be, used, breaking the electrical conductivity. Refineries, if they do high ends and most do, use an extensive network of buried copper bonded to all structural steel. this seems to be a simpler application of that practice. Sugar mills and graineries, take notice.

It's a great system, but limited in that it must be installed and inspected ( at least around here) in the time frame between building the forms for the footing and pouring it.

Getting the foundation people to cooperate has been difficult, especially when the only people who benefit from it is the electricians.

If the inspectors could accept that , yes, we DID bond to that 20' piece of 5/8ths rebar, HONEST!!! then there wouldn't be a problem & the foundation people would play along.

Maryland requires that the foundation rebar be used as the grounding. Since it is a requirement, the foundation contractor leaves a stub of rebar sticking out of the foundation near the service entrance.

I was troubleshooting one house where the microwave and stove controls were erratic.

The owner had watched the building process and stated that the house had two layers of poly sheeting under the basement floor slab and foundation. The rebar was entirely inside the concrete, not stuck in the soil.

When the ground was tested, it was found to be almost 300 ohms. The electrical contractor added a ground rod which dropped the resistance to around 30 ohms. While it did not meet NEC and there were several amperes flowing on the ground the AHJ did not require any additional grounding.

The utility then made some modifications to the transformer in the yard (perhaps secured the neutral) and the problems cleared.

The owners' now have a very dry basement and working microwave and stove controls.

Thanks Mike for presenting the paper regarding Grounding. The explanation and method for TABLE 1 is very clear but for the supplementary installation is not very clear. Can somebody explain the summary for both the methods.

Great article! Curious about the smudgy inches on the last document. Where it calls out the no.4 embedded electrode exposed X number of inches above base of footing.

Brian Bean

One flaw of measuring electrical resistance with a typical multimeter is the low Voltage/Current used in the measurement. You can have a connection with one strand of wire, and it will still show resistance on the bottom end of the meter's resolution - probably tenths of an Ohm. In operation, the higher currents may lead to a significant Voltage drop at this one strand left connection, and possibly failure of that last "hair" from resistive heating.

The resistance measurement doesn't tell you about the ampacity of that connection.

The accelerated corrosion of copper pipe from grounding has been debated at length. With Copper prices causing Gold and Silver to look over their shoulders, PVC seems to be the order of the day for new construction as well as repairs, and the contribution of the plumbing system to the grounding system is going away.

I don't think the connection to the earth beneath our feet is as important as everything being well connected together at a single point so transients become a common mode event. It's great to dump the energy surge into the dirt, but who has data showing how well these different systems accomplish that?