View Full Version : Can I run a hot to the panel without neutral and use ground rod to complete circuit
Kharnivour
Jan 16, 2010, 08:44 PM
Hello,
I have a property way out in the country and need some temporary electricity. My neighbor's panel is 300' away and he is willing to let me run wires from his panel to my single phase 120v panel.
But I don't have the money right now to buy (3) #6 wires each 300' long.
So my question is:
Can I run just one hot #6 wire without an accompanying neutral to the lug of the bus bar in my main panel. The neutral bar in my panel is connected to the ground bar which in turn is connected to a ground rod in the earth. That way the breakers get electricity to feed the branch circuits and the neutrals from the branch circuits are connected to the neutral bar which is connected to the ground bar and then the ground rod.
Would this work temporarily? I have heard that a single supply wire can overheat if it does not have a neutral or ground running alongside it to cancel out the sine waves.
Missouri Bound
Jan 16, 2010, 09:06 PM
You are joking, right?
KISS
Jan 16, 2010, 11:24 PM
Hey, just like the guy that put plastic finger things to keep the electricity from leaking out.
No, you can't. A ground rod should also be driven at the secondary location. The ground rod is primarily for lightning protection.
You failed to say what the load is at the other end so voltage drop calcs (typically <3%) can be done.
Why not rent a generator or use an inverter from a 12 V car/tractor etc.
tkrussell
Jan 17, 2010, 04:38 AM
A #6 copper wire will barely let you draw 20 amps at the 300 foot.
No, as stated before, you cannot use a ground rod as a return conductor. One, it is not allowed per Code, two, the earth will offer too much impedance to allow the circuit to operate.
Look up at utility wiring, you will see single conductors, and they are operating fine.
The issue with running a single conductor and heat is when a single conductor runs through a metal box, or conduit. If it does not have the return conductor near it, the metal box or conduit heats up. This heat is caused by Eddy Currents, small currents induced into the metal, caused by the fluctuating magnetic flux (field) surrounding the conductor. With AC power, the magnetic flux expands and contracts around the wire, due to the 60 cycle of the AC power.
I have found this phenomenon actually occurring with a 1200 amp 480 volt feeder entering a metal enclosure. This size feeder needs 3 large wires for each of the three phases, and happened to enter three knockouts. The electrician is to be sure to have one wire from each phase entering each of the knockouts. However, he did not,he had all 3 Phase A cables in on knockout, and so on. The metal between the knockouts was hot.
If there is any interest, with some time, I can provide an Infrared image of this event.
Having the return wire next to the feed wire is required to cancel out the strength of the magnetic flux.
If the ground rod plan were to work, the single wire you ran would not get hot because it does not have it's return next to it because it is not running through metal but in free air.
The generator or inverter is the best method of getting temp power.
Kharnivour
Jan 17, 2010, 11:27 AM
Thank you for your replies. Especially TKRussell and KeepitSimple. Thank you for taking the time to explain my question thoroughly. I did ask it after all to learn about completing a circuit and to keep me from doing something stupid. I will study up on impedance to better understand why the circuit would not function well using the ground rod as a temporary return.
To answer your questions:
I actually did plan to run the single conductor in free air along a fence. It is an empty field and there are no people. Again, it is just temporary for 12 days or so. I tried renting a generator and that option is out for right now. I understand that using the ground wire as a neutral is unsafe especially if an unsuspecting electrician came along to work on that circuit. But this is way out in nowhere and just for me to run a saw.
The load at my house would be under 20A. Enough to run a table saw or a circular saw and a light bulb or two. I will only be running one tool at a time since I am the only one there.
I thought that the return path had to go to the earth eventually (such as the ground rod at the main panel). After reading your responses in similar threads, it sounds like the return path goes back down the neutral that leads to the transformer where the hot supply wire originated. I don’t know how the circuit is completed at that point.
tkrussell
Jan 18, 2010, 07:03 AM
We get requests on how something will work that is not normally done, or ever. If we have not actually tried it, all we can go on is standard reasonable and customary theroy, standards, and trade practices.
If you want to try it, be my guest, and let us know how it works out.
While a power toll may have a nameplate of say 15 amps, any motor when starting, draws much more current althou for a short period. This starting current will be subjected to the high voltage drop. The motor will probalbly start, eventually, but will be serious hindered by the voltage drop.
If your power toll does manage to start, be careful when adding load, and be aware to not use it for prolong periods so it does not get damaged.
Kharnivour
Jan 18, 2010, 10:41 AM
Thank you TKRussel. So now that I have learned from all the comments about this subject, would it be correct to say that there is something about the design of a man-made transformer that creates a better return path than the natural earth?
tkrussell
Jan 18, 2010, 10:48 AM
Please explain?
would it be correct to say that there is something about the design of a man-made transformer that creates a better return path than the natural earth?
I am terrible at riddles or abstract concepts.
Kharnivour
Jan 18, 2010, 08:10 PM
[QUOTE=tkrussell;2182167]Please explain?
We ground our main panels with a ground rod but yet in this forum I have learned that the earth does not function as a return path for a circuit. So now I am confused as to why we ground our panels at all. But if the earth is not good for a return path of a circuit, then there must be something about the way a transformer is built, that does allow for a return path. I was recently told that the return path to the transformer is called a "grounded conductor". I also knew it as the "Neutral". The electrons would rather follow that than go into the earth.
So this raises another question: Is the transformer not grounded to the earth at some point? And why is the transformer's ground a better ground than the ground rod at my panel?
Thank you for your interest and any further info you might be able to provide
Missouri Bound
Jan 18, 2010, 08:30 PM
Kharnivour... OK, you aren't joking. What your initial proposal suggested is just unsafe but in theory it could work. But your last post poses a very interesting question, why IS the transformers ground better? I hope that someone here can answer that. In a pinch I have used the ground of equipment to provide voltage to a small power tool when no neutral was available (3 phase rooftop HVAC units) But that was a very short distance and certainly a tempory hookup, using a clamp to the machine's cabinet...
And I hope this thread keeps going... I suspect some interesting comments will come from it.
Best of luck
letmetellu
Jan 18, 2010, 08:31 PM
If you are going to just be using a light motored saw why could you not connect it to the altenator in your truck and use a hook up that would give you 120 volts. I thought that a brush motor would work that way.
Kharnivour
Jan 19, 2010, 09:06 AM
Kharnivour.....OK, you aren't joking. ...why IS the transformers ground better?
I am still unclear on one thing:
Does a transformer even have a ground connected to the earth? Or is it something about the windings and the taps that create the ground to which all circuits return back to?
And if a transformer is grounded to the earth and the return electrons from a circuit flow through the neutral back to the transformer and then into the earth, why is that ground at the transformer better than the ground at the main panel?
Kharnivour
Jan 19, 2010, 09:11 AM
...the earth will offer too much impedance to allow the circuit to operate.
TK gave me the answer and this leaves me wondering how the impedance at the transformer's ground is different from the impedance at the panel's ground.
KISS
Jan 19, 2010, 03:30 PM
On the top of this page there is an Electrical & Lighting link. Read the Sticky about Grounding.
Actually the electrons go from negative to positive. Conventional current goes from positive to negative. It's important in semiconductors and chemistry. One of the guys working with the electrical formulas got the sign wrong.
Quickly, the ground rod provides LIGHTNING protection. That potential is relative to earth.
LIGHTNING can raise the potential of the ground especially with distant buildings. That isn't good for electronics, etc.
The EARTH provides a REFERENCE voltage for you 240/120 distribution, your cable etc.
You also want your plumbing fixtures to be at the same potential as well. Water with impurities can come out of metal pipes buried in the ground. You would not want to touch your clothes washer and your plumbing and get a shock.
hermanwachs
Jan 19, 2010, 07:49 PM
Putting aside all the talk about electrons- I've seen more than one house with a overhead service with the "neutral conductor" ripped and the house running on the ground rod as the neutral. The neutral is really called the "grounded conductor" and is the center tap on the utility transformer. The houses ran just fine on the "ground neutral", quite to my surprise. Having said that I think this is a bad idea. For the cost of 300 feet of heavy wire you can buy a used generator.
Missouri Bound
Jan 19, 2010, 07:55 PM
I've used an inverter on my work truck to power light duty tools. If that wouldn't work, a generator may be the best alternative.
hermanwachs
Jan 19, 2010, 07:57 PM
The neutral is the messenger strand which carries the weight of the overhead, which is why it gets ripped. The center tap is grounded at the pole. The conductivity of the earth is too variable to depend upon for a good return path. A dry spell could really change the resistance.
KISS
Jan 19, 2010, 07:58 PM
hermanwachs: The system doesn't run off the ground rod.
Take this scenareo which is why it works in the case you describe.
1. There are multiple people on the same transformer.
2. Each has a ground rod.
3. Each has a neutral and ground attached to a ground rod except ONE PERSON.
4. The neutral/ground and water pipe connections are intact at the panel.
Guess what? The copper water line is the neutral in the case with the busted neutral (customer N).
Customer's N ground is tied to the panel neutral and the water pipe. The water pipe is extremely conductive all the way to the neighbors house. The water pipe picks up the neutral from the neighbor and carries it back to Customer N.
So, that's how it works.
If you put a clamp-on ammeter on the water pipe it may show a significant current.
johnmprince
Jan 20, 2010, 05:40 PM
Most of the houses around here have wells. When replacing the ground wire to my daughter's well pipe I got a pretty good tingle from it, conductors in parallel.
Stratmando
Jan 21, 2010, 02:18 PM
With that setup, you may be able to catch a lot of worms and groundhogs.