No, the ground should be at zero volts unless there is a serious problem where your ground was not connected to earth and then somehow became energized, but you would know this immediately because all things electric in your house would be acting strangely if not tripping off.

The ground wire is so thick that a trimmer string would not harm it.

BenTheGoodAg said:

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I think practically it's not an issue, especially in this application. But you might get some different opinions on having multiple GECs from a code perspective. I'd never do it in an industrial facility with sensitive control systems and long cable runs, and I take the continuous run section of the code to mean you shouldn't to limit ground loops. But in this case, I high doubt that it matters. Personally, I'm open to other opinions on that.

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Following up on this. Are there any options on having both an Ufer ground in the slab in addition to a ground rod? Good idea or bad?

There are options....the important thing as BenGood Ag mentioned is avoid ground loops that produce power quality issues that play havoc with your electronic data and equipment.

Most inspectors around the country I've dealt with interpret the code to not require the driven copper rod IF you use a ufer ground. There are some cities/counties that have added the requirement that if you use the ufer ground you also must drive the driven ground rod. So you don't have to unless its local code.

As a rule of thumb a ufer ground is going to be a much better electrical ground than a driven rod in most TX soils. However rules of thumb are broken sometimes in certain types of soils.

The important thing if you do both is make sure they are only bonded together at the main bonding point and not downstream anywhere. That will limit your potential problems with ground loops and electronic equipment performance.

Not sure that you're responding back to me, but I'll point out Underoos' response that he thinks it's OK if they're bonded at the same point and I would agree. He knows his ***** Strictly speaking, as long as you run a continuous (unbroken) ground wire to one of the two points, you can bond a second jumper anywhere along that path and you'd meet the code. You could also run a jumper between the Ufer and the rod and it would be good. Technically, this would be one GEC and one bonding jumper between electrodes. This is probably a better option if you're going to use both (my opinion).

Looking at your panel pic, it looks to me like your GEC is the bare conductor that runs from the left busbar, into the conduit, and then likely down to the slab. It's sized appropriately, and seems to follow the description on the inside of the panel. If all that's true, you don't really need the ground rod.

I wish contractors would take time to run cleaner wire routes.

Thanks for the replies. So they did come out and install the ground rod, but I have questions. They said the code for this area was to have both the Ufer and ground rod.

1. I think they only got the 8ft rod down 7 ft before hitting bedrock. Is this OK? He cut about 1 ft off the top.

2. Does it look OK how they attached it in the panel. It runs to the left side and also attaches to the panel case ground with the same wire. Would this be considered to be at essentially the same bonding point since it is a ground/neutral bus?

Is it OK? Yes.

Does it look OK? eh... The 7ft rod is fine especially since you have the Ufer. The busbar can count as the same point, but I would have picked adjacent terminals. I think they should have used a separate conductor to bond the conduit fitting, but it's not against code. None of these are showstoppers or will cause you any issues.

Thanks! Now I'm wondering if this overnight is something that could fall into the realm of lawsuit territory. The city inspector missed it, the electric provider missed it, my third party inspector missed it, and especially, the builder's electrician missed it. Wondering if there was any potential for serious danger had something gone wrong at the distribution transformer.

beatlesphan said:

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Side question as someone who is generally terrified of electric work since I had a previous house fire...if I hit that ground wire with my weedeater or accidentally touch it when I'm gardening, will anything happen?

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No.

No damages, just the negligence aspect of it. I was just curious. I don't have a lot of legal knowledge with this type of thing.

So I see two bare wires connected to the ground rod. One goes to the service panel, but where does the other one (one going to the right side of the rod) go?

Question


Main house a 200 amp panel

Detached garage 20 feet away from main panel has a sub panel



House was built 42 years ago


For 35 years the sub panel at the garage never had a ground rod. Ownership changed in 2017 and inspector said it needed it's own ground rod to meet code so ground rod was added. Before that there was only a ground going back to the main panel.

Did code change since 1982 that makes a separate ground rod mandatory at all sub panels ?

By adding the separate ground rod, does that help protect the garage better from lightening strikes ?

Gary79Ag said:

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So I see two bare wires connected to the ground rod. One goes to the service panel, but where does the other one (one going to the right side of the rod) go?

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He just bent the excess wire into a loop at the rod connection point. There aren't two wires.

Got another question for the experts on this thread. I have 2 ground rods in the ground next to my Main service panel with 1 ground wire from the SP to the 2 rods. Is it necessary and/or required for 2 rods versus 1?

Gary, for whatever reason, I thought you were one of our resident NEC experts.

Short answer, 1 ground rod is allowed if the impedance to ground is less than 25 ohms. If you don't meet that, you need a supplemental electrode (can be a rod or other type), but you don't need to measure it. There may be other local requirements.

JP, I thought I had a copy of the 1996 code, but I couldn't find it. There have definitely been a lot of cumulative changes to article 250 over the years, and it wouldn't surprise me if there were some differences in how it was written for what was probably the 1978 code. This is currently required in 250.32 and has been since at least 2008.

And yes, it's there mostly for lightning, but also for line surges, contact with other high voltage lines, and providing a stable voltage reference to the earth/structure. Not there for ground fault current.

BenTheGoodAg said:

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Gary, for whatever reason, I thought you were one of our resident NEC experts.

Short answer, 1 ground rod is allowed if the impedance to ground is less than 25 ohms. If you don't meet that, you need a supplemental electrode (can be a rod or other type), but you don't need to measure it. There may be other local requirements.

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LOL Ben, I'm just a jack of all trades, master of none type of guy and I've done it all to date... I've got a BSET degree, specializing in electronics, so I've got that going for me.

Just wanted to get an expert's opinion. The electrician installed it before I decided to remove the slider window in the master bedroom and replace it with a patio door. The second rod happens to be in front of the patio door. I'm planning to eventually install a concrete step in front of the door and was hoping I can just cut the ground wire to it and bury it within the step.

Thanks for your input!

I wanted to revist my question on whether or not cutting about 12 inches off the top of the ground rod is acceptable such that only about 7 ft was buried as was the case with mine. I read stories on other forums about electricians cutting ground rods short by much more than that because they couldn't get them down all the way and were too lazy to redo it, but the NEC says you need 8 ft buried.

How can I test the ground impedance? Or can an electrician do this to make sure I have a good ground? I was reading that you should have less than 25 ohms ground resistance.

You can do it yourself, with these methods, but I would have an electrician do it. You'll have to acquire some special equipment to do so. Cutting off the extra length is often a case of simple laziness by an electrician, but you're soils may be good to go. Some areas, as mentioned above, require two rods to hit the goal of less than 25 ohm. With your ufer and ground rod combo, I can't imagine you aren't hitting the goal.

The first electrician I called said that the clamp on tool for ground resistance testing like the below doesn't exist and he's been in business 40 years. He mentioned that they could "ohm it out" with a multimeter without disconnecting GEC from the meter which doesn't seem correct.

https://www.fluke.com/en/product/electrical-testing/earth-ground/fluke-1630

I wish I could rent one of those clamp testers to do it myself. I don't want to spend ~$2000 on one.

The electrician I called said that I "should be good" if 7 ft was in the ground and I have a slab bond. Still, I want to find someone who can help measure it.

BenTheGoodAg said:

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JP, I thought I had a copy of the 1996 code, but I couldn't find it. There have definitely been a lot of cumulative changes to article 250 over the years, and it wouldn't surprise me if there were some differences in how it was written for what was probably the 1978 code. This is currently required in 250.32 and has been since at least 2008.

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I had a 93 or 96 beat up paperback I tossed a few weeks ago when I cleaned out my office. 250.32 requires an electrode if you have a subpanel or anything fed by a feeder. If you had a single branch circuit or a multi-wire branch circuit feeding a light or receptacle or two, its not required. I've read on a couple of code forums over the years that once upon a time it was often ignored, or it started as a single branch circuit and later upgraded to a subpanel as the mancave grew, and the electrode at the out building never added.

Quote:

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And yes, it's there mostly for lightning, but also for line surges, contact with other high voltage lines, and providing a stable voltage reference to the earth/structure. Not there for ground fault current.

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I'd also argue that the electrode at the outbuilding does two things: 1. helps ensure a solid ground at the outbuilding if the equipment grounding conductor in the branch circuit or feeder running out there gets dropped, lost, cut, etc., 2. helps to eliminate differences in potential between the two buildings. Suppose the house and the shop are 200' apart. In some areas that could be enough to get into different soil conditions. You could have 15 ohms to ground at house A, but get 27 ohms to ground at shop A, because the reference point is 200' away.

HA_______________ SA

When you add the ground rod or other electrode at Shop B, and bond the equipment grounding conductor to it, you have ensured the impedance to ground is the same at both the house and the shop, because the grounding conductors at each building are bonded, i.e. connected.

HB_______________SB

Keep in mind having an adequate grounding electrode system may help shunt the energy from a lightning strike, but it's not going to help prevent one. Even full on Master Label lighting protection systems don't prevent strikes, they just give them a better target and a faster way down. As an example, a friend's house took a strike years ago. Fairly new house, GES current and correct. It hit the side of the house and rode the refrigerant lines to ground. Blew out the bend of the pipe where it connected to the condensing unit before going to ground. Cooked just about every appliance in the process. It also tripped GFCI receps 2-3 houses down on both sides.

Thunderstruck xx said:

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he's been in business 40 years.

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One of my biggest pet peeves is this answer, especially related to code questions. How is that legal? Well I tell ya, I been in the lectrical biDness foty years! Congrats on a successful career. Now show me the code reference indicating this is legal.

Ground rods get cut a lot because they hit rock, or hit A rock, or the arms give out on a T post driver. I'm not defending it, but 7' ain't too bad.

I completely understand wanting piece of mind to know it's correct - my wife and other friends give me grief when I get the level out hanging a picture - but as mentioned you have two different electrodes, the Ufer and the rod. The code only requires one, unless you are over 25 ohms then you start adding. Some cities don't read the exception in the code and will require one and a supplemental. You'd have to have some rowdy soil conditions to be over 25 at your place.

Thunderstruck xx said:

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https://www.fluke.com/en/product/electrical-testing/earth-ground/fluke-1630

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Well, its like they say, go big or go home. If you plan on doing it for a living, you end up with Fluke, Kleins and Knipex. But there is something to be said for Extech, Kobalt, and Wiha. I second the recommendation of having someone do it for you, but if'n you decide you really want to, this one's $300. The Fluke does it all at the source. This guy is the more traditional fall of potential method with additional electrodes.

https://www.grainger.com/product/9XKP5?gucid=N:N:PS:Paid:GGL:CSM-2295:4P7A1P:20501231&gad_source=1&gclid=CjwKCAjw88yxBhBWEiwA7cm6pU-Is3ihSMJxGKZckmU-s3CfatGtvsVTZmRWZvuUVh8Afv5Ut5l9XRoCA_gQAvD_BwE&gclsrc=aw.ds

That's a cute little 3 point FOP tester. If you really want a test with some chest hair, look for a machine that can do the 4 point method.

Do y'all know any good electricians in the San Antonio area that might be able to do the test with one of those Fluke meters?

I thought most electricians worth their stuff would actually measure the grounding impedance before calling it "good."

Try Suberg Electric or DeWinne Electric. Tracy and Ronnie are good dudes. They should be able to help you out. If they can't, try Eldridge. Stay away from the Mr Electrics and the folks on the radio.

Thunderstruck xx said:

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I thought most electricians worth their stuff would actually measure the grounding impedance before calling it "good."

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It's kinda like putting a thermometer in a steak. After the 100th time, you just kinda know - as several folks on here have noted. You shouldn't have an issue with two electrodes.

BenTheGoodAg said:

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That's a cute little 3 point FOP tester. If you really want a test with some chest hair, look for a machine that can do the 4 point method.

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Like I said. Kleins and Kobalt.

Ever get it measured?

Not yet, I'm waiting a little for the weather to get drier for the worst case measurement.