got my pto-generator today.

[mahlers]

</font><font color="blue" class="small">( mahlers,
It is against "code" to use the Earth as the sole means to ground/neutral. And very dangerous, usually doesn't work and will get someone killed. )</font>

OK, now I'm totally confused. In your earlier post, you said that the neutral goes down the pole and into the ground, and is the ground for the transformer. Isn't that, by definition, using the Earth as a ground? Help me out here...

 

[mahlers]

</font><font color="blue" class="small">(

The neutral is the return line in a 115 volt circuit, it shouldn't actually be needed in a 230 volt system unless the load is being split--which appears to be your case.

)</font>

Yup - and I needed 120 volt service where there was previously only 240. I tried to take a short-cut by making my own neutral (I won't go into why I tried to go that way, but I will say that I went through a miserable time trying to run 700 feet of #2 cable through the trees and over a river to get back to the main service entrance common). It was pretty obvious right away that making my own neutral wasn't going to work, so I ended up running the common all the way back to the entrance.

It still does go back to my original question about what the utility neutral really is. If I understand Inspector507 correctly, the utility neutral goes down the utility pole and into a coil of wire at the base of the pole - buried pretty deep down. That seems like a ground to me, and my twisted logic would tell me that I could drive four or five ten-foot copper ground rods into the soil and accomplish exactly the same thing. It didn't work, and I'm still curious if there's some other magic done at the utility transformer that I'm overlooking here.

 

[johnbilt]

Hi

Let me give this a try. I've read a few of the responses and am not sure if they answered your queston directly.

1) There are three wires from the "service side" feeding your meter and panel. The transformer on the pole has a center tap which provides a neutral (grounded conductor per NEC). This is the electrical return path for the two 120volt circuit legs.

2) The neutral (grounded conductor) is connected to earth ground at the service pole, as well as the service entrance (your panel and meter). This allows the center tap transformer to reference the potential at earth ground. Otherwise the system will "float" with respect to earth ground.

3) The neutral (grounded conductor) carries the return electrical current. This is different from the earth ground connection, which does not carry any current except in a ground fault condition.

4) Be careful with the NEC. This is primarily written for the service entrance and distribution beyond. I think there is another code for electrical service providers.

I hope I haven't created more questions !! /forums/images/graemlins/crazy.gif

I believe that your service pole must be wired correctly. Consult a professional electrician or the power company if there is really a suspected problem with your service.

Be careful out there !
/forums/images/graemlins/cool.gif
John

 

[KennyV]

John
You are absolutely right …
at the transformer the center tap is grounded AND also sent to your meter which is also grounded, and then to your panel where it is grounded again.
If you have a situation where you have a 240 volt but no 120, this is not impossible, but the only way you can get 120 safely and reliably is either use a 2:1 transformer, this will effectively making this an isolation transformer, or you can rewire and run three conductors. That is, Both legs of the 120 AND a common.

The first can be expensive if you have any real current requirements, transformers are not cheap. The second is more practical in almost all situations.

Don’t use the earth for your return. That path will be a variable resistance, due to contaminate and moisture levels in the soil.
If you are not sure, have a pro check it out ... alittle electricity can take the fun out of everyones day.
Good luck, KennyV

 

[ns_in_tex]

Hi Snowman,

On mine, I ran a single fused circuit, fed above the main disconnect to a hall light, we seldom use. When the generator is in use, we flip this hall light on. It tells us when the power company has the service back on.

 

[v8dave]

</font><font color="blue" class="small">( To v8dave:

I was thinking that neutral should only be bonded to ground at one point only(main panel). If it was bonded at more than one point, ground loops would be created. Neutral and ground should not be bonded at the barn, current should only flow back in the neutral for a split voltage configuration ?????????? )</font>

Yup, and that logic was exactly what I thought too. But the county inspector (El Dorado County, California) made the electrician bond the new shop's panel at it's power entrance. I questioned the request and got an unintelligible answer, but interpreted it to have something to do with GFCI might not work properly--too many false trips. I wanted the approval, so I just shut up. The shop panel is about 150' away from the house, main, panel.

 

[_RaT_]

"John
You are absolutely right …
at the transformer the center tap is grounded AND also sent to your meter which is also grounded, and then to your panel where it is grounded again.
If you have a situation where you have a 240 volt but no 120, this is not impossible, but the only way you can get 120 safely and reliably is either use a 2:1 transformer, this will effectively making this an isolation transformer, or you can rewire and run three conductors. That is, Both legs of the 120 AND a common"

I have done this in the past on small parking booths where they have 240V only. Much of the equipment needs 120V so in order to get it I would have needed to run a neutral well over 1000'. By using a relatively small indoor transformer fused for the transformer size since the incoming feed was 60 amp 240V and the transformer about 3000 watts I was easily able to run the various calculators, a light and a very small AC unit (the booth was 4'X8'). I did need to bond the transformer. Mark

 

[Inspector507]

<font color="blue"> OK, now I'm totally confused. In your earlier post, you said that the neutral goes down the pole and into the ground, and is the ground for the transformer. Isn't that, by definition, using the Earth as a ground? Help me out here... </font>

No, what I said was, the neutral is attached to that wire. The neutral is already a grounded conductor and this is supplemental to that.
The ground in your house is for a safe return path back to the neutral conductor at the service equipment. Grounding electrodes will not do anything to provide a safe low-impedence path. The butt wrap the utilities use are for "transient" voltage....i.e. lightning.

 

[Inspector507]

Okay, I decided to post a reply to myself and try to clear up what the NEC® says about running power to a separate building as far as grounding/bonding.

(1) If you only run one branch circuit, and include a grounding conductor, no electrode or neutral bonding is required. But a connection to the neutral is not to be made.

(2) If you run a feeder to the building with no equipment grounding conductor, a grounding electrode must be installed and the neutral bonded to that electrode and the panel enclosure. This is provided you do not have any continous metallic paths back to the main building such as metal water/air lines, etc. And provided you do not have ground fault protection for EQUIPMENT. The average residential property will not have GFPE which is different than a GFCI

(3) If you run a feeder with an equipment grounding conductor, a grounding electrode must be installed at the building and connected to the grounding conductor in the feeder and to the enclosure.

All of this is in NEC® 250.32

 

[v8dave]

</font><font color="blue" class="small">( Okay, I decided to post a reply to myself and try to clear up what the NEC® says about running power to a separate building as far as grounding/bonding.

. . .

(3) If you run a feeder with an equipment grounding conductor, a grounding electrode must be installed at the building and connected to the grounding conductor in the feeder and to the enclosure.

All of this is in NEC® 250.32 )</font>

Ah ha, and this is the case in my situation. Why the county inspector didn't say this is a mystery to me. I suppose his explaination was good too, just not understandable.

Thanks Inspector.

 

[Inspector507]

<font color="blue"> but interpreted it to have something to do with GFCI might not work properly--too many false trips </font>

Makes no sense to me, since a GFCI doesn't care if you have a ground or not. It measures the difference between the hot and neutral. If there is any difference between them, it kicks out.
GFCI's are permitted to replace a non-grounded outlet.

 

[slowrev]

I have heard that long power runs will cause GFCI's to false trip. I have not seen it myself, and maybe it has to do with inductance or something like that. Not sure, just what I have been told.

 

[Soundguy]

I know that if you have a difference in ground potentials between two references.. you can have current flow between them... Ground loops are the constant source of hums and buzz's in audio equipment... usually resulting in you having to 'lift' the ground from the offending equipment, and use only the reference at the deck / board.

Soundguy

 

[slowrev]

Yep, ground ain't always ground. Ground bonding is very important in Telco work as well.

On the GFCI false trip thing. As I understand it they look for a current difference between the Hot and Neutral leads. If different then trip out. I don't think the ground is really involved there, must be the loop length/inductance causing a lag and the GFCI sees that as a difference and trips out.

Of course I could be totally wrong on how the GFCI's work /forums/images/graemlins/smile.gif

 

[SkyPup]

Thanks for the original post, I also ordered the same PTO-genny from Northern Tool, along with the PTO shaft and the trailer to mount it on.

Our log home is too large to power, but we have a 20' X 45' studio apartment on top of our barn which has a 5,000 BTU Wall AC, shower, sink, john, kitchen, refrig, TV, and a 3/4 HP well pump.

With two tractors (2004 Kubota L-3130 and 1985 Massey 1030) and a plenty of fuel storage, this should cover us for at least a month off the grid! /forums/images/graemlins/wink.gif

 

[TOMLESCOEQUIP]

Could someone explain, in general terms, how a transfer switch works, IE how it can isolate the neutral leg from backfeeding and how it's wired in to the box to prevent this ?? Does it go inbetween the meter and the existing box ?? how does your house obtain a satisfactory ground if the leg back to the pole is disconnected?? Its already been stated that an "earth" only ground isn't reliable.............Isn't that all you'd have if you take the neutral out of the loop ?? Am I missing something ??? Thanks............Tom

 

[Inspector507]

The neutral does not get disconnected in these types of transfer switches. It is a solid connection. Some of them will go between your meter and your panel. Mine is setting beside my panel, or will when I get it in. I am only transferring 10 circuits, not the whole house.

 

[TOMLESCOEQUIP]

If the neutral doesn't get disconnected...........What protects the linemen from the possible back feed of the 120 volt loop when it comes to the neutral buss bar?? I guess this is what I don't see as a difference between turning off the main breaker or using a "transfer switch ?? If you run a big enough pto gen to power your house, Do you have to rewire the whole existing panel of your house to a 2nd set of breakers in the transfer switch panel ?? (IE duplicate breakers for everything ) I just want a safe hook-up for my pto gen............I've lost power for several days before...........It would be nice to have a somewhat "normal" operation of the house rather than just a few basic circuits and extension cords running everywhere for extended periods..............I have the tractor capacity (HP) to run the whole deal so why not use a gen large enough to do everything ??

 

[Inspector507]

Even if the main is turned off, the neutral is still connected. Nothing wrong there. If you plan on running the whole house, you can install a transfer switch between the meter and panel, but they are expensive, since that now is going to be your "service disconnecting means" and must be listed as such.

 

[TOMLESCOEQUIP]

What is the difference in the way the transfer swithch is wired in that it doesn't send the neutral back feed you would get by just plugging the gen into a 220 volt welder outlet by making up a double male cord from the gen to the outlet ?? You could go as far as putting a extra box in with a knife type switch and hard wiring a cord to the gen ...............I don't want to beat a dead horse here but how does it keep the neutral safe for the lineman if the transfer switch doesn't break the possible flow ?? What does the transfer switch really do that the main breaker switch doesn't for the linemans safety ?? I'll quit now.............Tom