As the proud owner of a ca. 1825 farmhouse, I understand a lot of the challenges and adventures that come with playing "this old house", and it sounds like you have your share too! That said, I have no idea what it might take to rework your plan to take power from the main panel instead of that unused two-wire ungrounded circuit. Any chance you could pull a new cable there with an equipment ground and maybe a bit more ampacity? The lack of a ground at the point of hookup is definitely a problem and it all but guarantees that any "solution" you try will violate modern electrical codes. I think I understand the ground rods providing some protection against lightning and other surges but not being conductive enough to create overcurrents that will trip a breaker (though surely strong enough currents to trip the GFCI I plan to place on the barn branch circuit). Actually, equipment grounds have little or nothing to do with the operation of a GFCI. Because a GFCI works by monitoring the hot and neutral and only trips when they are out of balance, a GFCI doesn't even need a ground wire to function properly. But you should also keep in mind that, while a GFCI protects against ground faults, it doesn't provide overcurrent protection. Thus, in the case of a short circuit, the heat can start a fire while a GFCI continues to feed power! "Actually, as a side note, I once measured an impedance of about 10 ohms in a ground rod circuit. Indeed not low enough to generate the 20amp overcurrent to trip a breaker at 120V." Yep, you're spot on there and, actually, 10 ohms is better than average! With this in mind, you may have wondered why I recommended two ground rods. It's because recent code editions allow a single ground rod where the impedance is 25 ohms or less. If a single rod flunks this test, a second rod is required and many single rods do, in fact, flunk. Don't ask me why (practicality, I'd assume), but the two ground rods together don't have to pass the test--they're just presumed to be OK. So it ain't all pure science, if you catch my drift. :-) "I am starting to get the feeling that unless I establish a (green) equipment-ground wire in the house circuit and connect it to the main panel, there is no way to take electricity to the barn and still meet code." That's my take too. "I assume that by equipment-ground you mean the wire that is normally green in color but sometimes grey or bare copper. Yep. (While gray is technically designated as an alternate color for neutrals, those old green ground wires do sometimes look gray.) 1. Maintain separate neutral and ground bars in that panel. (You may have to buy a small ground bar for a couple of bucks or, if there are two bars and they are connected, they need to be disconnected.) There is only one bar in the small barn subpanel. But no problem, say I buy a small separate ground bar. If you still have the packaging materials, they'll probably say somewhere the correct part number with the notation "sold separately." (Thanks, folks.) It's best to use the designated part although, in truth, those short ground bars are fairly interchangeable. 2. In your house, connect the equipment ground wire to the ground bar. In a main panel, there is often only one bar, serving both neutrals and equipment grounds. (That's fine in a main panel. In a subpanel, however, they should be separated.) There are no equipment-ground wires in any of my house wiring. That is, there are no green, gray or bare copper conductors anywhere. All wires in my house are 2 conductor wires, just one white and one black (hot+neutral). The only ground (bar) is inside the main panel where the neutral from the utility pole attaches. See, for now, I was planning to feed the barn circuit from an existing, unused, 20amp two conductor (black+white) house circuit. This house circuit was originally used to feed an old radiant space heater in one of my bathrooms (that bathroom is the closest room to the barn anyway so tapping into that circuit for the barn is most convenient). I disconnected the old radiant heater a long time ago for safety reasons and since that was the only appliance on that circuit, this circuit is now unused and available, I assume, to feed the barn. But it is strictly a 2-conductor wire (black+white only). Sigh, I feel your pain. (Really! No sarcasm intended.) 3. At the barn, connect the equipment ground feeder to the subpanel ground bar and land your branch circuit ground wires there too. In other words, all the (green) equipment-ground wires go to the subpanel ground bar. However, there is no existing (green) equipment ground wire coming from the house. If one is needed I would have to install one on a separate route and run it all the way to my houses main panel. True, true and true. (Not to get too picky here, but technically speaking, the EG is supposed to run in the same cable or raceway, btw.) 4. Drive two 8' grounding electrodes (ground rods) at least 6' apart and connect them to the panel ground bar with #6 copper wire. Again, from what I understand, unless I install that (green) equipment-ground conductor from the house main panel to the barn, then I should probably not ground/earth the barn subpanel at all. IMO, earthing the barn panel is a good thing in any event. What is to be avoided is a "false equipment ground". (That's a made-for-purpose term meaning that if the EG's are connected only to a grounding electrode, it may create a false confidence in addition to a code violation.) Somewhat better (although not fully code compliant!) would be to bond the neutral and the grounding electrode at the barn's ground bar. (That is what is done with a so-called three-wire 120/240V outbuilding service--the neutral effectively serves to feed both grounded conductor and grounding conductor.) But note that, as ronnatalie has correctly pointed out above, this approach is not strictly applicable in your case because there are other metallic connections (e.g., the phone wire) between buildings. Now that would take another long-winded discussion, but suffice it to say that the code only permits a neutral-EG bond when the house and outbuilding have no other connections. That may be a technical glitch, but it's a potential violation nonetheless. If I do run the (green) equipment-ground wire from the barn to the houses main panel then I should probably ground/earth the main panel only using rods implanted somewhere close to the main panel. If your house really has no earthing system, that would be a wise improvement in any case. It might also be useful to evaluate your plumbing as a potential source of earthing. If your water service is metalic when it enters the house, and runs at least 10 feet in the ground, you should also connect the water supply at the point of entry to your main electrical panel. With an old house, seemingly simple projects do tend to mushroom, don't they?

"Two hots with a shared neutral is an elegant system called a MultiWire Branch Circuit. The neutral carries the difference between the two hots. For instance with a 10 amp hot and an 11 amp hot the neutral would carry one amp. It runs cooler, with less stress on the insulation, than the same thing with two neutrals. The two hots must be on opposite 120V legs. What many people call "phases." This is most safely done with a handle tie or by using a double pole breaker." The thing is I only have single phase electric, so I don't see how MWBC is even possible in my case. So if the two circuits have a share neutral, the neutral wire is taking the combined loads right? The breakers are not adjacent to each other either. Granted this was back in the 70s when it was wired under who knows what code... That's why I wondered if someone had originally used the wrong green color for neutral wire because they ran out, and later on someone else opened up that box and uncoupled the green and created the single phase shared neutral circuit. So basically right now I have a shared neutral in a single phase. I have an seemingly unused wire but of a different color. I was going to pull a new white conductor for this...then I thought, wait a minute, what is this green wire doing here?

I just think that the commercial market will eventually force out the practice. Modern computerized offices can't get any work done with the power off, so separate neutrals will become standard in new construction specs. This are already becoming common, due to the number of non-linear loads from electronic ballasts, printers and computers. NEC-mandated "chaos" will only add to that practice. From the viewpoint of office managers, the 2008 code effectively requires that circuits powering unrelated loads be grouped on common breakers. The need for additional circuits is often only recognised and addressed when an overloaded breaker trips. At present the effect is only felt on that one circuit, but with 3-pole breakers in use the effect will be far greater. And the inconvenience of work done on one circuit be shared by workers on completely different circuits. And when a new circuit IS added, we will no longer be able to pull a single hot through existing conduit to share an existing neutral with a circuit located across the panel without also pulling a separate neutral. Businesses go to great expense to install or lease office space with generator backup because of the cost of the loss of power. They will certainly pay a premium price for commercial space powered by individual circuits on separate breakers - requiring separate neutrals be used. Finally, with increased service market pressure to NOT turn off 3-pole breakers in order to work on a single circuit, there will be more instances in the future of people choosing to work circuits hot - regardless of NFPA 70E - and increasing insurance industry pressure to require separate neutrals on all circuits in NFPA 70.

I'm back.. After the daisy chain discussion, I came to the conclusion that their is a huge difference between Commercial/industrial and residential. Being that this site is geared for residential, i just read the posts now. I stand by my statement though, jobs are engineered all the time with multiple circuits sharing a neutral on single pole breakers. If thats a new code change then we will adjust. Greenmile never stated what his circuits were for, and like i said before why do you want the lights to go out when you trip a receptacle circuit? If your concerned with the safety of not having a two pole breaker then just run the extra neutral. Simple as that. Journeyman i think you are right. there is a big clues bunch who have ego problems and just wait for people to slip up on their code and then they have to prove how much code they know ( Proud of you ) Like to see them with their tools though. I think very electrician out there can be taught a thing or two. There are many ways to skin a cat. Petey i don't think my statements are so erroneous. You took a couple of mispoken statements and tried to hang me over them. I'd love to work with you on a job to see your skills. I think you would get schooled. With that said, i will continue to read this site because i do enjoy reading about the different methods guys use to get jobs done.