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It should trip the breaker as that’s what it’s designed to do.
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Not an electrician.... Ground rod hammered into the ground? I'm guessing the ground/dirt isn't really conductive enough to transmit 110 volts with any reasonable/measurable level of current. I voted nothing happens. Now, a bolt of lightning hitting something attached to the ground rod? Like shit through a goose. Slightly higher level of voltage.  |
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So what's the correct answer? It isn't going to just create a direct short that will just burn power indefinitely. |
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On the vast majority of ground electrode installations? Nothing happens. Most ground electrodes are fairly high impedance connections to the earth. There are ways to design, install, and test low impedance ground connections. |
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If it's not the SAME ground rod as the incoming power: Nothing significant will happen. While it is "grounded", I think the impedance would be too high to trip the breaker. (unless a GFI is used, as previously mentioned)
"Ground" is great for lightning, but it's not the same thing as "neutral". |
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It will depend a great deal on the grounding. In most situations, not a lot will happen. It probably won't even trip the breaker, as it'd be hard to imagine a low enough impedance between the ground and transformer to get to 15+ amps. My guess; a decent blue spark and some moderate heating of the wires. If this was a circuit experiencing a ground fault and a GFCI was present it would trip the GFCI. The low amount of current on the ungrounded wire would probably be enough of an imbalance to trip a GFCI as that same current isn't being returned on the grounded conductor wire. |
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On the vast majority of ground electrode installations? Nothing happens. Most ground electrodes are fairly high impedance connections to the earth. There are ways to design, install, and test low impedance ground connections. I'll just be following the guidance of the experts, which I'm clearly not one. Interesting to me anyway. |
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Quoted: You can hook a wire from a 15Amp circuit breaker directly to a ground rod and it won't trip the breaker or smoke a small wire? It will just draw power at below 15 amps using the ground as the load consuming the power? If you connected a short #28 gauge wire or something, it's possible that enough current could flow through ground to cause the wire to fail*. But, without knowing the impedance of this particular grounding and length of wire run it's not possible to calculate the exact current that will flow and thus the absolute minimum sized wire needed. The 120v value is the voltage of that leg relative to ground and to the neutral tap of the transformer. But neutral and ground aren't really the same thing. The impedance, or resistance if you want to think in terms of DC, between a ground rod and the ground can be quite high. The impedance between the hot leg and a neutral wire is very low, since that loop is formed by copper. Same voltage, potentially very different resistance and thus different currents. Now, some grounding rods are bonded directly to the neutral. Shorting a hot leg to that grounding rod is just like shorting to the neutral; that will trip your breaker and/or fail your wire. But not all are. *fail has a particular meaning here. A wire has failed when it has heated enough that the insulation on it is hot enough to melt or deform. The copper itself will continue to conduct quite happily after the insulation has burnt off, but no insulation means a likely short circuit or ground fault which means more heat which can result in a fire. Always remember; the breakers are there to protect the wire, not the loads. In order for that to work the wire and breakers have to be sized appropriately for each other. This is all in the code. Deviating from the code may still result in a working circuit, but may also present edge cases where your house burns down. |
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Quoted: This is the correct answer. The low amount of current on the ungrounded wire would probably be enough of an imbalance to trip a GFCI as that same current isn't being returned on the grounded conductor wire. You're wrong, but don't take it personal. It looks like 90% of electricians, even good ones, get this wrong. |
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You can hook a wire from a 15Amp circuit breaker directly to a ground rod and it won't trip the breaker or smoke a small wire? It will just draw power at below 15 amps using the ground as the load consuming the power? Quoted:
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On the vast majority of ground electrode installations? Nothing happens. Most ground electrodes are fairly high impedance connections to the earth. There are ways to design, install, and test low impedance ground connections. Two 500’ spools of #12 THHN connected together to make it an overall length of 1000’. Connect a cord plug to the two ends of this 1000’ coil of #12. Plug it into a 120v receptacle! What happens ?? |
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I was completely wrong. I'll be damned. It doesn't trip the breaker. Take a look at Mike's longer video, he's got one that's about 1:20 long and yesterday I watched the entire thing. My background in electrical circuits isn't strong enough to fully grasp what he's talking about in the minutia, but it still was the most interesting boring video I've ever seen. |
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You can hook a wire from a 15Amp circuit breaker directly to a ground rod and it won't trip the breaker or smoke a small wire? It will just draw power at below 15 amps using the ground as the load consuming the power? Quoted:
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On the vast majority of ground electrode installations? Nothing happens. Most ground electrodes are fairly high impedance connections to the earth. There are ways to design, install, and test low impedance ground connections. The vast majority of residential grounding electrodes I have seen have fairly high impedance. Greater than 10 ohms for sure. I wouldn't try this within a substation fence on a proper grounding grid. A recent rain storm, salty soils, high water table, and a crew paid by the hour with an grounding electrode tester could make it interesting on practically any system. And let's not get going on corner grounded delta. Or counterpoise grounding. |
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It depends on ground conductivity and the distance between the ground rod at the power panel and the ground rod the circuit is connected to.
If the ground conductivity is high enough, it'll trip the 15 Amp breaker/fuse. It it's too low, the ground will dissapate the electrical energy as heat. Standing between the two grounds could be hazardous to your health, though. 
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Quoted: @krpind Take a look at Mike's longer video, he's got one that's about 1:20 long and yesterday I watched the entire thing. My background in electrical circuits isn't strong enough to fully grasp what he's talking about in the minutia, but it still was the most interesting boring video I've ever seen. 
I wrongly assumed the ground would pull enough of a load to trip the breakers. To be honest, I had someone else do it since I'm laid up at home, but it was easily tested and anyone could replicate it I'm sure. If I were able to do it, I would put a meter on it and see what it pulls. |
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Quoted: Good to see you around again, and you are most correct. I am bidding on some structure grounding (the work, not the engineering) and decided I wanted to bone up on my grounding knowledge, I was surprised at how wrong I was with 99% of what I thought I knew about grounding. I'll just be following the guidance of the experts, which I'm clearly not one. Interesting to me anyway. Grounding is hard. I agree with you - interesting and plenty to learn still. |
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Picture this: Two 500’ spools of #12 THHN connected together to make it an overall length of 1000’. Connect a cord plug to the two ends of this 1000’ coil of #12. Plug it into a 120v receptacle! What happens ?? Quoted:
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On the vast majority of ground electrode installations? Nothing happens. Most ground electrodes are fairly high impedance connections to the earth. There are ways to design, install, and test low impedance ground connections. Two 500’ spools of #12 THHN connected together to make it an overall length of 1000’. Connect a cord plug to the two ends of this 1000’ coil of #12. Plug it into a 120v receptacle! What happens ?? Now, if you straighten the wires out so it's one big flat loop then the breaker will trip. |
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You can hook a wire from a 15Amp circuit breaker directly to a ground rod and it won't trip the breaker or smoke a small wire? It will just draw power at below 15 amps using the ground as the load consuming the power? Quoted:
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On the vast majority of ground electrode installations? Nothing happens. Most ground electrodes are fairly high impedance connections to the earth. There are ways to design, install, and test low impedance ground connections. 
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Quoted: I am not an electrician nor do I claim any ability to know wiring. That's why watching Mike Holt learn me up on grounding ended up very different than I expected. Watch the first 1:15 of this video-  https://www.youtube.com/watch?v=qNZC782SzAQ14 mins in was especially interesting about not grounding generators or solar arrays. |
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Quoted: @swampvol You're wrong, but don't take it personal. It looks like 90% of electricians, even good ones, get this wrong. I have personally done this test with a ground rod driven in fairly wet black soil, and there wasn't enough current to trip a standard breaker. Now that I think about it, there wasn't enough current to even measure on my Fluke clamp on....which does not read into the mA. Admittedly, I haven't tried it with a GFCI breaker. Are you saying that it would not produce any current at all? |
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Do you care to explain? Quoted:
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It happens all the time with flooded junction boxes and such; all that happens is the circuit breaker trips. Now if you are considering the stupid shit people do, then yes you can come up with other situations.  |
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My 100 amp service has a shutoff/disconnect at the meter on the outside wall. It then goes into the house on 2AWG service cable. I want to put two 60 amp sub panels up. First one in an attached garage but the cable is going to be buried along the house from meter area to the garage. The second sub panel will go in a detached shed. I’ll run 4 wire and have all the specs for direct burial cable requirements. I’m going to put a generator (whole house) transfer switch right after the service meter. Can I put a power splitter or a small main panel that sends power to the house panel, garage panel and then shed panel? If I’m running a grounding wire with the sub panel cable, how do I set up the grounding system at the panels? I was going to connect each subpanel back to the main panel in the house and then put a two rod grounding rod system at each subpanel. I think that’s only required if the panel is detached? With what I’m describing, what grounding system will be per code? |
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Quoted: On which part? You're wrong all the way around. I install a shitload of generators, and not once has the manufacturer instructions required me to add an additional ground rod/auxiliary GEC at the generator. Are you saying that is what you do, or are you just confused between the GEC and bonding? |
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Yep, I've only seen the requirement for an additional GEC for a generator is when the service neutral is being switched. Quoted:
Quoted: On which part? You're wrong all the way around. I install a shitload of generators, and not once has the manufacturer instructions required me to add an additional ground rod/auxiliary GEC at the generator. Are you saying that is what you do, or are you just confused between the GEC and bonding? |
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From what I have read, that is correct. It depends on whether the generator is internally grounding or not (I think I got that word right). That decides if you switch neutral on the safety transfer switch. It also decides if the generator has its own grounding rod. If I remember correctly, the code does require a grounding rod with certain generator types. |
| OP, in a similar manor, say a line falls from the pole. A live line on the ground will not trip any fuses or breakers as the current flow, while signifigant for danger is not enough to likely ever open a safety device like a fuse or breaker. What happens is a ground fault as I alluded to in one of my previous posts. These are dangerous, especially at primary voltages and higher because of the voltage gradiant that exists. Now you have step potential, that is, where your feet are, each could be at two substantially different potentials (or voltages) and that difference in potential could have lethal consequnces with the currents that could flow into and out of the body. |
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Thanks for that vid. 14 mins in was especially interesting about not grounding generators or solar arrays. Quoted:
In what way? I have personally done this test with a ground rod driven in fairly wet black soil, and there wasn't enough current to trip a standard breaker. Now that I think about it, there wasn't enough current to even measure on my Fluke clamp on....which does not read into the mA. Admittedly, I haven't tried it with a GFCI breaker. Are you saying that it would not produce any current at all? |
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OP, in a similar manor, say a line falls from the pole. A live line on the ground will not trip any fuses or breakers as the current flow, while signifigant for danger is not enough to likely ever open a safety device like a fuse or breaker. What happens is a ground fault as I alluded to in one of my previous posts. These are dangerous, especially at primary voltages and higher because of the voltage gradiant that exists. Now you have step potential, that is, where your feet are, each could be at two substantially different potentials (or voltages) and that difference in potential could have lethal consequnces with the currents that could flow into and out of the body. I've seen some interesting training on bringing the workspace on a pole to the same potential as well, so that the lineman is protected in his potential envelope. I don't climb poles (or turn wrenches, or drive a crane or anything else useful) so it was interesting but kinda in one ear and out the other. Now I'm trying to get a better understanding of it. But I still have no intent of climbing poles. |
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These two answers,combined, are correct. There's not a lot of info in the OP but: 1. if a GFCI is installed it will trip immediately. If not, then 2. if a breaker or fuse is in the circuit it will trip within seconds. If not then 3. wire will produce heat, followed by smoke, followed by sparks (maybe). In any case it will be over shortly. Quoted:
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Depending on there size of the wire, it will either melt the wire insulation and turn it into what is essentially a heating element until failure of the circuit or trip the breaker. So my answer is "not enough information provided". 1. if a GFCI is installed it will trip immediately. If not, then 2. if a breaker or fuse is in the circuit it will trip within seconds. If not then 3. wire will produce heat, followed by smoke, followed by sparks (maybe). In any case it will be over shortly. |
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what happens when your solar array is hit by lightening? I thought it was interesting that the risk of current going UP the ground rod into the equipment was a bigger problem than needing to dump excess current off the equipment inside the building. But you're exactly right, if you isolate the solar panel from the potential current (uh, not sure how to rephrase that) that could go 'backwards' from a lightning strike pushing current up the ground rod, what happens when it takes a direct hit? You've introduced a ton of energy, what happens to it? |