Worse case high voltage scenario

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ghostbuster,
The solution was to remove the neutral jumper between primary and secondary of the pool's distribution transformer.This was approved by all the electrical safety agencies.
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If the bond was completely removed and not replaced by a Ronk Blocker or other such device then there is no protection in the event of a primary to secondary winding fault.
Don
 
Thanks for all the response

I also liked the link.

Don

I know you're right about the utility bonding adding fault protection against high lines falling on secondary lines.

But two wrongs don't make a right. This is something else that maybe the power utilities need to correct.

They make us walk the line maybe they need to do the same, after all you can't or shouldn't be able to put a price on a life although most Large Corp. do all the time.Electricians in my city get their houses turned down from something as simple as a 1/2" bushin not on a 1/2" Emt conduit connector on a basement recpt. Then you can drive all over town and see service drops with no kind of insulation on weatherhead connections.Of course that should be another thread by itself.

By the way I am not familiar with the Ronk blocker I did a search and couldn't find anything. Is it a guard or what?

Also I don't get the connection of how the grounding rod helps the Po.Co other than fault protection they have a two wire circuit on the high side of a single phase system it might help just a bit if they don't use a large enough grounded conductor. Au is that the reason my lights are brighter when it rains?:D

Thanks:)
 
Ronald,
It is my understanding that the Ronk Blocker is an open circuit between the primary and secondary grounded conductors until the voltage between them exceeds some value (I think 300 volts or so) and then it becomes a short circuit between the two grounded conductors.
Also I don't get the connection of how the grounding rod helps the Po.Co other than fault protection they have a two wire circuit on the high side of a single phase system it might help just a bit if they don't use a large enough grounded conductor.
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I have seen statements that say as much as 1/3 of the primary grounded conductor current returns via the earth as a result of undersized primary grounded conductors. Every connection to earth lowers the resistance of the primary grounded conductor.
Many of these problems would go away if the utility would use phase to phase power to all transformers, but that is more expensive so they use phase to grounded in many cases.
Don
 
Thanks Don
I understand how that could work, but don't see how it would help if we had a open in the grounded conductor on the high side? It would definetly see more voltage than that with the open grounded conductor.

About the rods then our lights might get brighter on a rainy day then:D
 
local utility

local utility

it is my understanding in the area in that I live when the utility provides a secondary service the do not want the building ground tied to the utility ground at the transformer they want two seperate systems, however if like was stated earlier there is a fault within the transformer in the windings than I do not know what would happen?
 
Mike,
it is my understanding in the area in that I live when the utility provides a secondary service the do not want the building ground tied to the utility ground at the transformer they want two seperate systems,
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I don't see how that is possible...XO will be tied to the utiltiy ground at the transformer and to the building ground at the service.
Don
 
Don , I understood him saying they have eliminated the transformer utility bonding jumper making the closest thing possible to a SDS without Removing all earth grounding.

Back to PO.Co grounding.

Why don't they just run a large enough grounded conductor to start with and have a rainy day everyday?:D

Or maybe just upgrade to a larger size when demand calls for it, maybe their customers wouldn't have as many brown outs if they upgraded every 50 years or so.
 
Ronald,
Don , I understood him saying they have eliminated the transformer utility bonding jumper making the closest thing possible to a SDS without Removing all earth grounding.
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If they do that, then they cannot supply a grounded service.
Don
 
ronaldrc said:
I have redrawn this scenario with the utility grounding jumper.

http://home.comcast.net/~ronaldrc/wsb/High_voltage_illistration.htm

Chances are of this ever happening are very slim.
But never the less it could happen.
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Great thread everyone. Definitely makes a person think.

Now, looking at the diagram, with the broken line side high-voltage grounded conductor, how much current would actually flow in the service drop neutral and the GEC?

Say we have a 100 amp load in the dwelling (which is probably higher than normal). So multiply this by 240 volts equals 24,000 VA.

Let's go with 34,000 volts to ground on POCO primary. The current which would travel through the primary winding and then down the service drop neutral to the GEC would be 24,000 divided by 34,000 equals .7 amps.

What about the high voltage on the neutral? Since the neutral is connected to the center of the secondary windings, and also connected to the earth through the GE, there would not be any drastic increase in the potential difference between any of the secondary service conductors, branch circuits, etc.

The only place I see a large potential difference may be between each side of where the original wire was broken on the primary side. And even that is subject to debate based on the different resistances of the dwelling GE and what is on the other side of the broken wire.

Now, considering that we don't hear about thousands of fires and thousands of electrocutions caused by this phenomenon, I don't think it is as bad as it is made out to be. Of course, I may be wrong, and there may be a huge government/media/poco conspiracy involved.;)

I haven't read the IEEE report cited above, but will do so shortly.
 
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ronaldrc said:
Mark the utility bonding jumper is not discussed that much, Bennie had a big problem with it and I agree.

It could possibly be the cause of a lot of the Electrical fires us Electricians get blamed for.Check out the link below



http://home.comcast.net/~ronaldrc/wsb/SV_Utility_.htm

Although this says nothing about burndowns I still have my feelings.
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Quoted from your article:

"The earth currents always take the path of least resistance back to the substation."

You might want to change it to say: ALL paths...

Also in regards to Stray Voltage:
I'm not an expert on this subject by any means, but stray voltage, in the general sense of the word, doesn't kill. It's just very low voltage caused by load imbalances that are typically on the order of 10 Volts or less. Not lethal, although it is sometimes discernable by cows, I guess?

Contact voltage, on the other hand, can potentially kill, but is VERY different from "Stray Voltage."

And yes, "Stray Voltage" it is caused by the neutral connection. Unfortunately, if that bond is disconnected, then the Earth becomes the sole conductor, which violates the NESC.
 
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I'm not surprised of not getting any feed back from utility Engineers on this
topic if that where my title I probably would not reply either.

Anyone that understands basic electrical circuits can see how dangerous this could be.

In all the reports I have read on this subject and of stray voltage from this problem none have discussed or mention this worst case scenario of a broken primary grounded conductor. And how all the primary voltage can be directed into the customers property through their neutral conductor.If everyone wants to just keep their heads in the sand theres nothing I can do.

Thanks
 
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A note

A note

Home_Utility_transformer_hookup.jpg
 
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