why?

[Buck Parrish]

True story. The water and drain pipes are much better grounds then the grd. rod.
And in some cases, even connected to other houses utilities.

 

[rwreuter]

in your opinion do you think if a GEC was run with the feeders that issue would have been avoided?

what did you to do remedy it?

 

[rwreuter]

you know having done ALOT of research on this subject i just read another opinion or rather analysis of this.

"Analysis: In the 2005 NEC, 250.32(B)(2) permitted the neutral conductor to serve as the effective ground-fault current path, this rule was converted into an exception for existing premises. Using the neutral conductor to connect metal objects to the effective ground-fault current path is a dangerous practice, especially if the neutral becomes open."

I agree with this statement.

Though while not questioning this reasoning I will say that we are doing this in millions of new homes everyday, everything is grounded or bonded to the grounding electrode system and the grounded conductors.

If the service entrance conductor neutral becomes open then current will flow through the easiest path, whether it be the water system or the electrical panel (because the bus bars are bonded to the panel).

Just and observation.

 

[ceb58]

I'm under '08 and it's still three wires from the meter pedestal to the house.

Dose this pedestal have disconnecting means? If not we are talking two different things. If you do not have a disconnect then you are talking service conductors. 250.32 (2005) Deals with feeders. The OP has a disconnect located on a pole away from the building.

You keep avoiding this (2) there are no continuous metallic paths bonded to the grounding system in each building or structure involved,
The phone line will be bonded at the building and that same line will be bonded somewhere else.
If I remember correctly your OP was due to the fact of the cost of installing the extra wire. We could discuss this from now on. My opinion and experience with this is you should run the EGC. You and only you can make the call with the info.you have. And as you stated you have no one in authority to make the determination per 2005 code.

 

[LarryFine]

If anyone is interested, I have a theory about when and why a 4-wire feed is required, and when it's optional. In other words, "why."

For the typical 3-wire utility supply, whose neutral carries current, the premises neutral voltage (relative to the system ground and/or the earth itself) may rise a few volts, but it does so as a whole.

In other words, adequate bonding minimizes potential differences, or gradients, between various surfaces that we consider grounded, such as EGC's and GEC's, enclosures, and the plumbing syetem.

Note that beyond the main bonding jumper, the neutral, the grounded conductor, is treated as a non-grounded conductor, other than OCP. And, relative to our premises ground, it's prudent to think of it as such.

In a detached building, there's a whole new premises with its own interior system with neutral current, which means that structure's neutral may also rise above the originating supply's neutral voltage a bit.

As in the main house, we don't really care if the system ground has a little voltage above zero, as long as it rises as a whole. The presence of another conductive pathway from the main house changes all that.

A cable-TV coax, for example, has a shield that could act as a ground reference to the neutral and either develop shock voltage between them, or force neutral current on the shield. Neither are desireable conditions.

Now, with a 4-wire feeder to the separate structure, the neutral voltage can rise a bit if it likes, without creating a voltage difference between the main house's MBJ-point and this strcuture's grounding system.

Well, I don't know where I was really headed with this, except that's how I see it, and maybe thinking about it helps with the theory hidden behind the requirements. Hope it was informative.

 

[hurk27]

Not that this is a relevant question but there were grounds driven. True story or hypothetical?

Either way point well taken and I can follow what is happening.

I hope you do not depend upon ground rods to stop stray voltage, they can not and will not stop voltage gradients, and as far as I'm concerned are worthless, if you got some time please read this thread, and you will have an eye opener!

Time To Eat Crow also follow some of the links in there to the other threads to understand where this all got started.



As far as your OP, I have to side with Bob (I Wire) I feel if there was going to be a big change in the way the utility feeds our services, like with 4-wire from the transformer to the service, then I could agree with the requirements of the 4-wire from the pole to the buildings, but to me it is a waste of resources to require 4 wires when feeding a building from a disconnect out on a pole, when there is no NEC requirement for the disconnect, the only time we are required for a disconnect and OCPD's is when we enter a structure, yes we can call a pole a structure but at what point does the conductors enter it??? they don't!

Does this utility require over current protection at this disconnect?
if not then I would call it a load break and say it doesn't meet the definition of a service disconnect, thus allowing service entrance conductors to continue on the the loads.
This would be very true if this disconnect was allowed to be ahead of the meter, then it would be a meter disconnect and not a service disconnect.

Even though the 2008 has changed the requirements of not allowing 3-wires, I will still keep setting 200, 320 meters with double lugs to feed an out building, by not entering a structure the meter is on, and treating these conductors as service entrance, which will not require 4 wires. run right back into the ground from the meter over to the out building, hit a main breaker, install a GES, and be done. all of which is required for an out building anyways.

Not that I don't agree with the code change, to make enforcement clearer, I think there should have been some addressing the fact that there is installations like a pole mounted service, which make no sense to run 4 wires when you got to hit a disconnect at the buildings anyways.

 

[ceb58]

Larry, very good explanation. For once you were being on point untill

it heps with

 

[LarryFine]

Larry, very good explanation. For once you were being on point untill

it heps with (and fixed - thanx!)

At least I can spell "until."

 

[rwreuter]

After having read and reread many, many posts and articles, I still believe that I would be in FULL compliance with the 2005 NEC because (IMO) it is referring to the structure feeding power and the structure receiving the feed. If what you were saying is true then ANY building that would have a phone line/TV ect run to it would be inelgible for this exception. I just don't think it is the case and is not what they were referring to. Agree to disagree.

Having said that, I do see the larger potential safety problem here and that is if there is a problem with the neutral (grounded conductor) then the only path for the electricity to flow is through grounding electrode system (rods, water pipe, gas pipe ect....) and it would energize the panel and perhaps the water in the house. BAD!!!!

By having a GEC you would have a floating neutral and a ground bus bar bonded to the panel, so if the Neutral would fail or faulter there would be no possibility of electricty flowing anywhere (unless it arcs). This is safe and is worth the money.

This setup is not possible in normal residental housing because the meters are mounted on the house and the panel just just inches or feet away and is fed by a 3 wire. From what I now understand, if there is problem with the neutral, everything attached to the bus bars will be energized. Though I may be making a mountain out of a mole hill, it lines up with what everyone here is saying and explaining the need for a GEC.

Just curious, what would happen if you isolated the grounds and had a floating neutral in a normal residential set up? Again just curious why (outside of because the NEC says so) don't we do it that way?

 

[hurk27]

Just curious, what would happen if you isolated the grounds and had a floating neutral in a normal residential set up? Again just curious why (outside of because the NEC says so) don't we do it that way?

Well because you wouldn't have a fault current path back the the source (transformer), this is the main reason the bonding of the EGC's to the grounded conductor (neutral) has to take place somewhere.

 

[triplstep]

Just curious, what would happen if you isolated the grounds and had a floating neutral in a normal residential set up? Again just curious why (outside of because the NEC says so) don't we do it that way?

What purpose would the grounds serve if no connection was made to the grounded conductor at the service?

 

[rwreuter]

Does this utility require over current protection at this disconnect?

Not that I don't agree with the code change, to make enforcement clearer, I think there should have been some addressing the fact that there is installations like a pole mounted service, which make no sense to run 4 wires when you got to hit a disconnect at the buildings anyways.

Yes it does require there be a disconnect (200amp)

And I agree completely with you on the fact that the NEC should have addressed the issue of meters/panels mounted on polls, they should not have treated them as a typical building structure.

Though, from following all the paths of current if there is a failure in the system somewhere, I like the safety features of the GES not being tied to the Grounded Conductor (Neutral).

 

[rwreuter]

Well because you wouldn't have a fault current path back the the source (transformer), this is the main reason the bonding of the EGC's to the grounded conductor (neutral) has to take place somewhere.

got it, with a four wire set up the GEC and Grounded Conductor are bonded together at the Feeder source.

 

[hurk27]

Larry, very good explanation. For once you were being on point until

I agree with Larry's explanation in whole, but what I don't see is where the installation of a disconnect out on a pole makes using a neutral wire for grounding changes the danger when the NEC doesn't require a disconnect out on that very same pole?

 

[hurk27]

Yes it does require there be a disconnect (200amp)

And I agree completely with you on the fact that the NEC should have addressed the issue of meters/panels mounted on polls, they should not have treated them as a typical building structure.

Though, from following all the paths of current if there is a failure in the system somewhere, I like the safety features of the GES not being tied to the Grounded Conductor (Neutral).

I agree, and I wish it would start at the transformer, to go one farther, I would like to see utilities stop the bonding across the transformer from the primary neutral to the secondary neutral, we would resolve 99.9999% of all stray voltage problems, and yes there is a device they can install to prevent high voltage cross over, its called a neutral block, but don't hold your breath for this to ever get changed

 

[hurk27]

Yes it does require there be a disconnect (200amp)

Yes but requiring a disconnect and requiring over current protection is two different things, disconnects are also rated for the current they can handle, and yes they do make them without over current protection.

 

[rwreuter]

I agree, and I wish it would start at the transformer, to go one farther, I would like to see utilities stop the bonding across the transformer from the primary neutral to the secondary neutral, we would resolve 99.9999% of all stray voltage problems, and yes there is a device they can install to prevent high voltage cross over, its called a neutral block, but don't hold your breath for this to ever get changed

Also, if they would do this, we more than likely would not be discussing this issue at all.

We can prevent and prevent and protect everything on our end but if it leads back to the POCO and they are still doing it.....well, where does that leave us? Chasing our tails.

 

[rwreuter]

Yes but requiring a disconnect and requiring over current protection is two different things, disconnects are also rated for the current they can handle, and yes they do make them without over current protection.

You are correct. My bad, they want an over current device installed. I will check with them though and verify. If they will accept a disconnect, by the 2008 NEC you still have run a GEC (structure to structure).

 

[hurk27]

Also, if they would do this, we more than likely would not be discussing this issue at all.

We can prevent and prevent and protect everything on our end but if it leads back to the POCO and they are still doing it.....well, where does that leave us? Chasing our tails.

The whole point of my arguement

 

[rwreuter]

At least by me pulling a GEC if there is any neuteral fault I won't be energizing my water pipes, gas pipes, electrical panels and ect, ect in my house.

Also, I won't be allowing the wrong current to flow (or not) so the breaker won't trip as someone explained earlier. To be honest I didn't understand what they were saying but I have read it in several place and several people stated it, so I take it, it is an electrical principle.