Hi all, my first question here. Thanx in advance for any help.
May seem like a dumb question, but can I run a 100 amp. sub panel off of a 100 amp main panel, and if yes, how. I’m fine with the connections, separating neutral from ground etc., but all of the info i read talks about the sub-panel with less amps than the main. I can’t find anything with the same. Does this make sense?
Thanx again,
Graves
Replies
I,ll put inmy 2cents to keep this going. Yes, you can feed another 100 AMP panel as a subpanel, however, your total load for both panels cannot exceed the maximum capacity of the main panel. It is often handy in remodeling situations where you dont have enough open spaces to handle new circuits. Note that on your main panel, the nuetral and ground wires are bonded together whereas on a subpanel the nuetral and ground must be run to separate buss bars that arenot bonded. This is usually done with an add in buss bar sold as an accessory for the particular sub-panel.
Actually, My own home has 100 amp service, with a 100 amp sub in basement, a 70 amp sub in workshop and a 40 amp sub in a storage building. Probably does not meet current code but I am sure we never draw too much amperage in total, just have a lot of separate circuits set up in various buildings
Thanx for your answer.
Do I understand your situation correctly?
You have a 100 amp main panel, then a 100 amp sub panel?
If yes, how are they connected (breaker, wire, etc.).
If not, do you know how to set that up?
Cheers,
Matt
Graves - I also have a 100 amp subpanel in a woodshop running off my 100 amp main panel. However, I determined I only needed 60 amps capacity in the woodshop, so I've got a 60 amp breaker on my main panel which feeds the subpanel. I connected the two using 6 AWG wire after also taking into account the distance between the main panel and subpanel. The 60 amp main panel breaker protects the 6 AWG lines to the shop, and the individual subpanel breakers protect each of the lines out there.
For what it's worth, I used a GE 100 amp subpanel already designed for workshop use that is sold at Lowe's....the advantage being that it's already got the separate neutral and ground buss bars.
charlie -- "Count your blessings....it could always be worse!"
Just wanted to say thanx.
If I want 100 amps in (to) the sub panel, I use a 100 amp breaker in the main panel right?
Cheers again,
Matt
If I want 100 amps in (to) the sub panel, I use a 100 amp breaker in the main panel right
Graves - the short answer is yes, but I really have a hard time believing you need 100 amps going to a subpanel.....and if you really did, I have a hard time believing your main panel could handle the additional load.
Read Renosteinke's post #10.....and then read it again. I'd be saying the same thing if he hadn't already said it.
There's lots of details in doing what you're proposing to do. There's questions you need answers to that I'm not sure you know enough to even ask. And on top of all of this there are local codes that vary depending on where you live.
I think you need a qualified electrician on this one.
charlie -- "Count your blessings....it could always be worse!"
Edited 1/14/2008 2:57 am by charlie4444
I think that you are going to have a hard time buying a 100 amp breaker to fit in your 100 amp main panel
lol....good point! Never even considered that since I'd never seriously want to do that. Looked it up and GE, Square D, etc all make multiple kinds of 2 pole 100 amp breakers..... More than one of the GE variations looked like it would work if I was the one wanting to do that....but dunno, could be wrong.
'Tweren't me that wants to, though......it's Graves that somehow has a need to.
charlie -- "Count your blessings....it could always be worse!"
Edited 1/14/2008 12:00 pm by charlie4444
"Graves - the short answer is yes, but I really have a hard time believing you need 100 amps going to a subpanel.....and if you really did, I have a hard time believing your main panel could handle the additional load."First he did not say that he needed a 100 amp feed, rather if he could attach an 100 amp sub panel.And it is a valid question. Even when someong is only feeding a sub-panel with 50-60 amps I recommend that they get a 100 amp sub-panel100 amp panels are common, inexpensive and have lots of slots for expansion where small panels are often limited to 4 or 6 slots.But someone else ask the same question recently and it turns hout that he did want to feed it with a 100 amps.Bascially he was moving his panel as part of on going upgrades and wanted the freendom to move circuits as needed..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Bill - all you say is true, but I wasn't answering his original question in my post #11. I had italicized the new question I was answering...you must have missed it. It was:
If I want 100 amps in (to) the sub panel, I use a 100 amp breaker in the main panel right?
None of us know exactly the reasons for what the OP is trying to do....he hasn't enlightened us as of yet. Might help a lot if he did, though.
charlie -- "Count your blessings....it could always be worse!"
Edited 1/14/2008 2:33 pm by charlie4444
Ok...wow...the help you've all offered is great!
Here's the reason for the "100 amp sub panel":
Just bought the other half of the semi we live in. We are going to take over the basement. We will access it through our basement.
We want to rent out the rest of the new aquisition.
The "main panel" is 100 amps.
I want to give the tenants a panel in their abode for all (and only) their circuits.
Their panel will be for a whole household, and I will have a shop in the basement.
Lights, and gas furnace, perhaps central air conditioner (for their household), and one power tool and dust extractor run off the basement panel (the main panel).
Any and all advice is greatly appreciated, and again Thanx
Graves
You're going to rent out space above a shop? With power tools? Or is this a quiet kind of shop?
quiet
Best of luck. We actually live in our basement and rent out the main floor, because we don't need much room, just the two of us.Use your intuition when choosing tenants! Our current tenants are awesome. Our last tenant, well. . . when he left, he wrote insulting notes to me on the walls, with a sharpie, and left a great variety of other minor damage. We didn't see eye-to-eye.
Edited 1/14/2008 3:07 pm ET by Biff_Loman
I'm confused now.
Existing 100A panel in your "old" house, you want to pull a 100A subpanel to somewhere to supply power for something.
You bought the other half of the "semi" and want to rent all but the basement to an unknown tenant. Keep the basement to use as a shop under the rented living space. Access to shop is through your "old" basement.
I am assuming that "semi" means a semi-detached house, AKA a duplex or a twin? Two homes which share one common wall.
My question ------- where / how did the "other half" of the house get power before you bought it?
Are you just trying to power your shop with this new subpanel? And that shop happens to be in the rental property basement?
JimNever underestimate the value of a sharp pencil or good light.
i agree with the other two replies. You first need to calculate your usage on the main panel. Keep in mind that not every circuit will be used to capacity. concentrate on your large eaters, dryer , electric heat, water heaters, ovens etc. Often times these circuits will be used simultaineously. (Saturday afternoon shower while my wife cooks dinner and runs a load of laundry.)Use the amperage on the appliance not the breaker. For the second panel use a full 100amp panel (use a main panel if it's not in the same room as the first so it has a main breaker on it. if you do end up using a main, remember to isolate the neutral busbar from the ground, you may have to add a seperate grounding busbar) and fuse it @ whatever you can on the main. I run 1/0 thhn in conduit to my subpanels, the conductor costs more but it really saves your #### when the main panel gets replaced and you subpanel fills up with the circuits added on from that third bathroom, shop, second laundryroom, etc. If the panel is more than 50' from the original, run new ground rods. you'd save in conductor what you'd eat in labor, and the lowered rsistance in you're grounding cricuit is well worth it.
Caution! Beware!
"If the panel is more than 50' from the original, run new ground rods. you'd save in conductor what you'd eat in labor, and the lowered resistance in your grounding cricuit is well worth it."
This is very dubious. Ground rods are not an acceptable substitute for a proper ground wire [equipment grounding conductor].
~Peter
Right. The suggestion of new ground rods would not be acceptable here. You should have a proper EGC all the way back to the original panel. And remember that neutral and EGC is NOT bonded at the sub.Scott.Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.”
The ground rod statements, and comments about load calculations, are reasons why this job really ought not be attempted by the DIY. Hire a pro. There are design issues, decisions to be made, that you simply can't do just by attending a Home Depot seminar. No matter what, you need a ground wire going back to the main panel. Driving a new ground rod, one that is not connected to the other ground rod, creates a new danger. Don't do it. Period. Can you run a 100 amp panel from another 100 amp panel? Sure you can. How to do it? Well, there are a few different ways. The main question to answer, though, is: Do you need 100 amps? Or, do you simply want a certain number of circuits - and the panel you saw with that quantity of spaces was marked "100 Amp?" An electrician would make a 'load calculation' of what the panel was expected to power. Suffice to say, there are quite a few 'rules of thumb' that are used, and they have nothing to do with totaling the ratings of the breakers. If I were to make a wild guess, you probably will need less than 60 amps at that panel. The breaker used to supply the panel, as well as the wire size used, will also be determined by that load calculation. There is absolutely nothing wrong with feeding a "100 amp" panel with a 60 amp breaker. As many know, you would keep the grounds and neutrals completely separate. Do NOT use the green screw that comes with the panel. DO mount a separate ground bar.
Peter...Scenario "A": You run a new sub panel.You run an ecg all the way from the ground buss bar on that sub panel back to the main panel, 50 feet away. At that main panel, the ECG goes where ? To the ground. The ground is what ? A Ground rod !! (Or two or three, whatever the code is for the area.)Scenario "B": You run a new sub panel.You run the ground buss bar to... A ground rod !! (Or two or three, whatever the code is for the area.)Given the same detail in rod, clamp, and conductor from the ground buss to the rod... What makes "A" acceptable, and "B" not ???
I'm gonna grow me some wings. And I'll learn how to fly !
The differences are two: First, at the main, the wire doesn't just connect to a ground rod. It also connects to the utility neutral.
The ground rod has absolutely nothing to do with clearing faults. The ground connection to the utility neutral is what allows a short to trip a breaker.
Why? Because electricity is always trying to get back to wherever it came from. In this case, "home" is the utility transformer (and NOT Mother Earth). Second, the ground is a terrible conductor. It is very possible that the areas around two different ground rods will have a difference in voltage between each other. The situation is particularly dire in swimming pools and dairy sheds; that's why the code has additional grounding requirements for those areas.
That's also why the code requires different ground rods to be connected to each other. That's why you simply MUST run a ground wire between panels, regardless of whether you have a ground rod, or not.
Ok, I can see the point.I would argue that, there is a nuetral conductor running the distance between the two panels. What comes from the trasformer to the main does not include a ground. Only the nuetral and two powers. The ground is added at that panel.Why is the second panel not treated as the first ?Nuetral and two powers coming to it from the first, and the ground added at the second...It would in essence, be a separate power panel. Equal to the first in some ways, but still subordinate. I don't mean to be argumentative. It just doesn't make sense to me.Cost ?
I'm gonna grow me some wings. And I'll learn how to fly !
First, to address Stuart's point ... there's been a fair amount of controversy over the years about treating a separate building as a separate structure. That has been addressed in the 08 NEC, with a simple rule of 'one meter, one service.'
The reason? Because ground wires, and other metal pathways, are not supposed to carry current ALL of the time. When you feed another building, you really have no way to ensure that there will be no other paths connecting the buildings, apart from the neutral wire.
Returning electricity will divide itself between ALL available paths. You really don't want to create a spark when, say, you're working on the gas line. Or the water line. Or anything else. Nor do you want 23 amps returning via the ground braid in the TV cable. Otherwise, it's correct that there is no ground wire between the utility transformer and the house.
First, there's no need, because the neutral and ground are connected at the main - this lets the ground paths clear faults. Take away that bond, rely only on the ground rod, and you will never trip a breaker.
So what is the ground rod for? More than anything else, for lightning. Everything that sticks up from the ground might get hit by lightning; the ground rod helps address this issue. That's why separate buildings require their own ground rods. Yet - often overlooked - code still requires these additional ground rods to be tied into the same ground 'system' as the first. If you don't do that, you run the risk of one area having a different "ground" voltage than another. Since people, and animals, are generally more conductive than the world around them, you're setting the stage for a nasty shock - or worse. Every now and then, we'll hear of someone's dog getting electrocuted while walking down the street; invariably, the dog has stepped on an energized manhole cover ... and electricity has found it easier to travel a few feet through the dog, than a few feet through the ground all around the manhole cover.
It is this issue that lies at the root of many of the fancy phrases you hear bandied about ... 'stray voltage' ... 'equipotential plane' ... 'voltage gradients.' In short, the 'ground' is NOT a 'ground.' That the NEC is poorly worded is an understatement; in some ways, it's quite confused. Some is simple bad grammar, some is the result of competing interests over time, and some parts are just plain wrong. That's why I often remind folks that the NEC is neither a design guide, nor an instruction book. Follow good trade practices, have a good design, know the trade ... and code compliance will follow. The opposite case is another matter ...
Reno,What you say =sounds= good.On the surface.But you really haven't addressed the point.It still does not make any sense to me.Nate pretty much summed up what was in my mind when I first posted here...How does/did anyone come to the conclusion that a 50 foot route to ground was better than a 6,8,10 foot one ? (In fact the 50 foot one is 50 foot PLUS 6, 8, 10, whatever...)In one of your examples... If I have an accepted ground at the sub panel, and lightning strikes... That strike is much more likely to follow my short path to ground, than that 50 or 60 feet of coax. Or any of the other 50 foot conductors.***Returning electricity will divide itself between ALL available paths.***Every now and then, we'll hear of someone's dog getting electrocuted while walking down the street; invariably, the dog has stepped on an energized manhole cover ... and electricity has found it easier to travel a few feet through the dog, than a few feet through the ground all around the manhole cover.Which is it ? Shortest path/path of least resistance... Or all paths at once.Even if it is both, the greatest part of that strike is going to go throught the shortest path, the path of least resistance.***Otherwise, it's correct that there is no ground wire between the utility transformer and the house.
First, there's no need, because the neutral and ground are connected at the main - this lets the ground paths clear faults. Take away that bond, rely only on the ground rod, and you will never trip a breaker.Aaaaand you are right back to my original question... Why not treat the sub panel the same as the main ?If you connect the nuetral and the ground at the sub, and your ground meets the code specific to it's location, (In other words, you have to meet all the same code requirements here, that you met at the main.), you have created in essence, a second version of the first.This box is then going to act just like the other box. It is a main.Problems in this building do not have to find their way all the way back to the other building, (no matter what or how many other paths there might be...), because it is taken care of right here and right now. In exactly the same way a problem in the other building would have been taken care of by the other panel in the other building.In a nutshell, if I have a panel in this building, that is built to the same code specs as the main panel was... This panel is the "main" for this building. It just happens to be fed from another main, rather than from a transformer.
I'm gonna grow me some wings. And I'll learn how to fly !
Not to sound abrupt, but I've been trying to condense several years of schooling, plus my experience, plus the literature of the entire field, into a few paragraphs. As such, several different topics have been touched upon ... grounding, bonding, lightning, physics, etc .... it's really not appropriate to cut and paste disparate statements, assemble them out of context, then nit-pick the Frankenstein you've assembled. There are three statements that terrify me, when someone utters them. "Electricity doesn't know the difference" is one of them. When I hear that, I know I am going to find all sorts of 'creative' things done. Fast-forward to the closing: many, many 'mysterious' and 'intermittent' problems are solved when a qualified person simply rips out all the hack work, and re-does thing the 'right' way. Some of these 'trade practices' have been validated, as we learn more and more. Others only come into play when something goes wrong. What's the difference? Bond the neutral and ground anywhere but the main panel, and you violate code. Fail to connect ground rods together, and you violate code. Fail to run a ground wire to the sub panel, and you violate code. Chances are, things won't work right, either. And, yes, that sometimes means taking things on faith. I've never seen an electron .... or carried a bucket of volts. Yet, the various theories - which are chock full of contradictions - do a reasonable job of letting you accomplish the task at hand.
You don't sound abrupt at all.I have taken no offense. And I hope I have given none.In fact I really appreciate the fact that you have taken this time.I do understand that the code is the code. You follow it, or you pay the consequences. But I am trying to understand more of the "why" of the system, rather than "just because I said so, young man !"As for frankenstein... I absolutely agree. I do understand what you are saying, and I also understand the frustration there is, in trying to wade your way through all the possibilities when someone starts frankensteining things.Let me back up here, and start from the beginning. Hopefully it will make things a bit easier...Let's pretend..I got this great deal on a vacant lot, across town.I decide to build a tiny little cottage on the lot. I mean small. Just a place where I can go for a weekend and read, to get away from everything. One bath. Small kitchen. Washer and dryer. And one small communal room with a bed loft.The entire place is built correctly. Permits, code, etc...The electric service is installed correctly. It has passed inspection, and is all ready for hookup. Just hasn't been hooked up.Now, this box is going to be fed electricity. Once fed electricity, it is going to do what all mains do. Exactly what all mains do. Nothing more, nothing less. It is an entire system, all on it's own.Yesterday, I was given a great deal on the old house, on the nextdoor lot. ~50 feet away. That house has a 200amp main, and the total useage of the house isn't more than 80amps.Now I have to choose. Do I run my cottage service off of an 80 amp breaker in the other house, (And only have to deal with one electric bill.), or do I go ahead and run out to the transformer ?What I want to know is... Why this system suddenly becomes inadequate, or unsafe, just because the nuetral and two power conductors are hooked up to another main, rather than being hooked up to the transformer ?
I'm gonna grow me some wings. And I'll learn how to fly !
We need to break this down into several areas.One problem is that the term "ground" is used several different ways and means several different things.So I will use the words that the code uses.EGC (equipement grounding conductor) - the green or bare wire that runs from the panel to a sub-panel or to the 3 pin on a receptacle.The EGC serves two purposes. One a path to safely conduct fault currents back to the panel and if the fault is "bad enough" it allows enough current to flow to trip the breaker.The other purpose is to make sure that metal that you come into contact in a building (or near by) is at the same voltage. Anytime that you allow current to flow through a conductor you will have voltage drop. So the only way to know that everthing is at the same level is to have a "reference" conductor which normally does not have any current flowing through it.That reference conductor is the EGC. It connects to all of the metal on appliances via the ground pin on the plugs and indirector to the metalic plumbing by the bonding that happens at the main panel. In a metal building (aka Butler Building) the building metal is also bonded.Now if you have a sub-panel in the same building the the EGC is run to the sub-panel and the neutral is not bonded to the EGC at the sub-panel. If the neutral was bonded then part of the neutral current would flow through the EGC and then it would be at a different voltage level that the EGC's that connected at the main panel.And if you tried to use a ground electrode instead of the the EGC to the sub-panel, as noted in another post that I just made, the resistance would be way to high to clear a fault.If the sub-panel is in a different structure that has no other metal pathes back to the main structure (such as a water pipe or tv cable) then there is no metal that is referenced back to the main panel so you can "start Over" with the EGC at the out building by bonding the neutral to the EGC at the sub-panel. The Ground Electrode System. That consists of the ground electrodes and ground electrode conductors. There are a number of ground electrodes, but underground metal water pipes and ground rods are the most common. All of the ground electrodes are connected to the main panel and bonded to the neutral and at that point the EGC's connect via the ground bus.The GES serves completely different functions than the EGC.One purpose is to ground any transformer leakage current. The primary of the power transformer is in the thousands of volts. IIRC 7 and 14 kv or common level.With capactive coupling the secondard of the transformer could be several hunderd or even thousand of volts above ground. Now that would not affect anything in the house. Everything would be connected hot to neutral or hot to hot and would still see 120 or 240. And people in the house all of the metal would be at the same potential. But someone outside use a receptacle connected to that house or touching the metal on a metalic building would seee the several hundred volts to ground.Thus by bonding the system to the GES that high voltage is bleed off.The other purposn of the GES is to provide a path for any lightening strikes.Each building that has more than a single circuit (12o or 240) needs it's own GES..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Thank you Bill.I really appreciate your time and your response.If I read that correctly, the bottom line is that my new little imaginary cottage is exactly right. ......So long as there are no other metal connections/conductors between it and the old house on the neighboring lot.The entire cottage system would be left as-is. A standalone electrical system. And just the nuetral and two power conductors run to the 80 amp breaker, and the neutral buss bar in the old house.This is the way I thought it should be.Sometimes, through no one's fault, the advice on the forum can be a bit difficult to understand. That could be the reason it so often seems that people are being told to treat a totally separate structure, as a sub-panel on threat of fire and death...So to nutshell...If the new panel is anywhere in the same structure, or is in another structure that has some electrical pathway to the current structure, (Be that metal conduit, or whatever... Anything that will act as a conductor, other than the three conductors needed to feed the power...), Then it should be treated as a sub-panel. The neutral and ground should be separated in the new box, (sub), and an EGC shuld be run between the main and the sub.But if the new panel is in a separate structure, and the two structures are linked ONLY by the three conductors, (PPN), that carry the power to the new box... Then the new box is to be treated like a separate service. It should meet all codes and standards of any new structure/service. It should have the nuetral and ground busses bonded, and should have it's own adequate and code reliant GES.Is this right ? Or have I misunderstood ?
(edit: 'like a separate' and 'as a separate' don't mean the same thing at all. ;o) LOL)
I'm gonna grow me some wings. And I'll learn how to fly !
Edited 1/14/2008 10:43 pm by Luka
Two minnor corrections."Then the new box is to be treated like a separate service.
It should meet all codes and standards of any new structure/service. It should have the nuetral and ground busses bonded, and should have it's own adequate and code reliant GES."It MAY, but does not have have a 3 wire connection to the main. I believe that I have heard tht Washinton State does not allow it. And I believe that in this thread someone mention that the 2008 NEC no longer alows this. But both are hearsay.The other is that the outbuilding needs it's it own GES reqardless of whethr is it connect to the main via a 3 wire system (service entrance like) or 4 wire (sub-panel with isolated neutral).
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
HmmmLooks like I need to get some research done.At least I have some idea of what/how to research now.Thanks again, Bill.=0)
I'm gonna grow me some wings. And I'll learn how to fly !
Thanks all for some great information.
Every time I peel back a layer of the onion(confusion) I see the the potential damage the dumb azz (me) looking in can cause.
One more thing: not all 100a panels have bussbars rated to accept a 100a branch-circuit breaker....even if it fits in mechanically.
If you look at the piece of paper glued to the inside of the panel cover, it has the panel spec's on it, including a list of breaker styles and usually sizes that it accepts.
Putting in something else violates the listing of the panel.
Edit: I thought you were the original poster, from what you wrote. This was intended for him, sorry.
Ed
Edited 1/15/2008 8:06 pm ET by edlee
I knew he could do a WAY better job of explaining this.....Scott.Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.”
Maybe we will go with the Britsh and say Earthed..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Bill, I'm surprised you didn't jump right in and explain Luka's question about a ground rod for a subpanel. It was explained to me once, but I'm a bit vague on details.I believe that if the subpanel is in the same building as the main, which is the case here, then the code indicates that all circuits must be brought back to a single EGC and at only one point in the entire structure will the neutral and EGC be bonded. Therefore the EGC can be trusted to be completely isolated from the current-carrying neutral in it's entirety. This makes sense to me because if the two ground rods were close enough together in the earth, and one got hot, the other could potentially become charged.The rules change if the subpanel is in another building, like a barn. It is OK to use separate ground rods here.Make sense?Scott.Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.”
that's not true, in fact the NEC requires that a subpanel have it's own equipment grounding system if it's a certain distance from the main panel. I don't know that distance off hand, but we use the 50' measurement.
The '05 NEC allows a subpanel with a separate ground rod not connected to the service ground for one situation: if it's in a separate structure that has no other metallic connections to the main building (such as phone lines, water pipes, etc.), but I'm pretty sure that's going away in the '08 edition.
The EGC Doesn't return to the center tap of the utility transformer like the neutral. It's purpose is to create the least resistant path possible. Why would a 50' long conductor provide a better grounding circuit then a shorter one. I may be mistaken about what I said earlier but was pretty sure of the specifics(I haven't ever seen the code in print, but was told this by my inspector.)
"he EGC Doesn't return to the center tap of the utility transformer like the neutral. It's purpose is to create the least resistant path possible. Why would a 50' long conductor provide a better grounding circuit then a shorter one. I may be mistaken about what I said earlier but was pretty sure of the specifics(I haven't ever seen the code in print, but was told this by my inspector.) "Actually it's purpse is to create a path is will conduct enough current to clear a fault (trip the breaker) without doing damage to the equipment or people. So lets look at this "better conductor".There are a number of different types of reconized ground electrodes, one of the most common (specially in residentail work) is the ground rode.Code says that if you are using a ground rod and it's resistance is measured at 25 ohm then you only need the one. Other wise you need two. But there it is not required to test so that you might even higher resistance than the 25 ohms. And the test is specialized and rarely done. So standard practice is to use 2 ground rods and have no idea of the ground reistances is.But lets say that you tested this one and found it at 25 ohms and only used the one.How well will it do with clearing a fault.at 120 v dead short to "ground" it will draw 4.8 amps. Not near enough to trip a breaker.If what you have said accurate reflects the statement of the "inspector" he is not only an idiot, but also a danger to others..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.