Floating Neutral

[fishman19]

"Standard service originates at a utility transformer, with two ungrounded "hot' conductors and a neutral. The neutral limits the voltage on either hot conductor to 120V to grd. If broken the voltages become erratic."
Therefore SDV, sure you are absolutely right contrary to what many here believe.

 

[roger]

"Standard service originates at a utility transformer, with two ungrounded "hot' conductors and a neutral. The neutral limits the voltage on either hot conductor to 120V to grd. If broken the voltages become erratic."
Therefore SDV, sure you are absolutely right contrary to what many here believe.

I think you need to go back and read the posts again, I don't know who the "many" are that you are refering to.

Roger

 

[roger]

where did my reply go?

Are you saying you lost a post this morning?

Roger

 

[fishman19]

It seems a lot of readers are implying that as long as the house system is grounded then he wouldn't notice anything, and that can't be his problem. Of course others are relating that the house grnd. is not necessarily going to provide adequate path back to the transformer. Thanks

 

[roger]

I think there is only one that has said a ground rod would complete the circuit, however a few of us have mentioned that areas (usually older urban areas) served with metallic water systems can carry the neutral load but, it would be through the neighbors conductor(s).

Roger

 

[fishman19]

My apologies, I'm talking when I should be listening again!

 

[roger]

No apology needed, and welcome to the forums.

Roger

 

[sparkygriffin]

Why are my post not making it. I'm I being censored by a moderator? Who can't admit he is wrong?

 

[roger]

Why are my post not making it. I'm I being censored by a moderator? Who can't admit he is wrong?

I don't know what's happening to your posts, are you hitting something before you click on the submit reply button?

You are not being censored that I know of.

Wrong about what?

Roger

 

[cschmid]

The power company is NOT telling the truth. They are using the ignorance about the purpose of "grounding" in order to deny responsibilty.
What you probably experienced is two houses, fed from the same transformer, that were both "grounded" using a common waterline. When the neutral to one house was broken the neutral currents traveled on the waterline to the other house where they returned to the transformer via the ground/neutral connection on the neighbor's service. While this masked the problem, it created a potentialy dangerous situation. The grounding electrode (waterline) became a current carrying conductor for the neutral current. This is not a good situation. This possible parallel path for neutral currents is a flaw in our present power distribution system. I don't know how to fix it, but it appears to be a growing problem.

I think I know how to fix it..You quit using the water main as the supplemental ground so it does not tie structures together and then you are dependent on the neutral point connections..this would ensure proper maintenance of the neutral point connections and the bonding path..by allowing the opportunity of paralleled paths we also allow the potential unsafe situation to occur..The only reasons we ground a transformer is to allow a safe path for a high voltage surge and to stabilize the secondary voltage on a transformer..because the PO CO has the ability to swing the power 10% either way and when you swing high voltage the curves are greater and can occur faster..You can correct me if I am wrong on the stabilization function..

 

[winnie]

I never said it was a good situation I said that if his house was properly grounded he would not have known about the problem. That I believe was his question. And what the power company said.

This discussion is going down the path of different posters not using words in the same way.

_Proper_ grounding simply means meeting the grounding electrode requirements of the NEC.

_Sometimes_ such grounding will result in a solid metallic path back to the transformer neutral. That solid metallic path back to the transformer neutral is no where required by the NEC, and thus cannot be considered a metric of 'proper' grounding.

Not only is this _inadvertent_ parallel neutral not required by the NEC, but in situations where the NEC has control (separate structures on the same property), NEC rules would specifically prevent such a parallel neutral.

In situations where this inadvertent parallel neutral exists, it can act to prevent problems associated with an open neutral. However this benefit comes at the cost of other significant safety issues.

-Jon

 

[sdv]

Float'n

Float'n

Thanks everyone. I feel very confident that I already knew the answers. However, since this event can occur frequently at a home (my home!), and it is a potential fire hazard, I thought it was a good issue for discussion. You should have seen the burn marks on the electronics control input card of the washing machine. And, what also concerns me is that the meter box is locked by the utility, and they do not perform periodic inspections. The utility's neutral conductor came loose at the meter box. Not sure how?perhaps they stressed the cable at the pole. Regardless, it does bother me when there was a potential fire hazard, and the utility says that there's nothing that could have been do to prevent it. And even worse, makes an excuse that is technically incorrect.

I concur with the replies?that the effectiveness of the ground rod at the house has very little to do with ensuring a neutral current path to the transformer to prevent the voltage imbalances. The path (earth) is too unreliable. The ground rod at the house only prevents/minimizes shock hazard when the utility neutral is lost since the home?s equipment grounds are connected to the panel?s neutral and ground rod.

 

[roger]

I think one more point should be made as to the NEC's reason for Earthing, (Grounding), it certainly has nothing to do with completing a neutral circuit to the source.

250.4(A)(1) and(2)

(A) Grounded Systems

(1) Electrical System Grounding Electrical systems that are grounded shall be connected to earth in a manner that will limit the voltage imposed by lightning, line surges, or unintentional contact with higher-voltage lines and that will stabilize the voltage to earth during normal operation.

(2) Grounding of Electrical Equipment Non?current-carrying conductive materials enclosing electrical conductors or equipment, or forming part of such equipment, shall be connected to earth so as to limit the voltage to ground on these materials.

So, regardless of the POCO's position, a good ground doesn't relieve them of the liability.

Nowhere in the NEC is a GE intended as a return conductor for a service.

Roger

 

[sparkygriffin]

This is the last time I'm going to try to post on this subject. My censored messages were longer and more detailed. Every service requires two grounds if your house is older maybe you just have one. It's sounds like you just have a ground rod, if that ground was good, because of the bond that is required in your panel to the nuetral you would not have noticed a problem. Because the ground would have acted as a nuetral. Yes this is a dangerous situation but it would have acted like a nuetral. Because you either didn't have a ground or it was poor your system saw abnormal voltages. So what the PO. CO. said was true. Good grounding is the responsibility of the house not the power company. Roger do you get it?

 

[cschmid]

This is the last time I'm going to try to post on this subject. My censored messages were longer and more detailed. QUOTE]

If you were being sensored you would have a post with you name one it and a message saying " Message deleted" and signed by what ever moderator deleted it..

 

[roger]

This is the last time I'm going to try to post on this subject. My censored messages were longer and more detailed.

Once again your messages were not censored, it must have been something you were doing wrong

Every service requires two grounds

Can you point us to where this requirement is? If you build a house where none of the GE's listed in 250.52 (A) 1,2,3,4,6,7, exist, you would have to provide a rod and if that rod had a resitance of 25 ohms, your done.

It's sounds like you just have a ground rod, if that ground was good, because of the bond that is required in your panel to the nuetral you would not have noticed a problem.

Very unlikely that a rod would have a low enough impedance to the POCOs MGN to acheive this.

Because the ground would have acted as a nuetral.

Next to impossible at our low voltage.

Yes this is a dangerous situation but it would have acted like a nuetral. Because you either didn't have a ground or it was poor your system saw abnormal voltages. So what the PO. CO. said was true. Good grounding is the responsibility of the house not the power company.

Sorry, but it would have been more than a long shot that our grounding would not have helped, unless as stated earlier, there was a common water sytem to more than one service.

Roger do you get it?

Get what?

Roger

 

[Ruff Elec]

Floating Neutral

Out here on LI we experience them from time to time. I agree with the other posts that the ground rod will do virtually nothing, we have driven several down on top of each other, and get no ground. On LI we have water pipe grounds and have found that this will almost mirror the utility neutral. When we have problems as you describe if both the utility neutral and water main ground are open, we observed the differences in voltage you describe, hi and low on opposite legs, stand and watch the lights dim and increase in brightness, sometimes scary. Our utility doesn't compensate for much, and are protected in the tariff, however, they do pay for damages due to neutral being opened. Electronic type devices at 120 volts such as, microwave, TV, heating control boards etc will burn up pretty quickly. May want to reach out to some neighboring utilities and see what their policy is, if they will release that, and take it back to yours. I also thing the suggestion of homeowners is a good choice to investigate. One last thought, we have experienced high electric bills due to this condition, and actually tested it in a shop environment as well as houses, and confirmed the higher bills, which went against the engineers theory.

 

[sparkygriffin]

OK Roger, I don't know where you live but no where even close to where I live are you getting 25ohms or less on one ground rod. And 210.53 D2 will explain the supplemental electrode when required. We are just going to have to agree to disagree on this subject because you are just not getting what I'm talking about. I would ask that when you feel like just maybe I have a point you conduct a little test for yourself. It has been interesting bantering with you. I'm in MD. if the soil in your area is better great. Apperantly the soil were the original poster lives isn't though. I wonder how much resistance he has there? Most likley poor.

 

[roger]

OK Roger, I don't know where you live but no where even close to where I live are you getting 25ohms or less on one ground rod. And 210.53 D2 will explain the supplemental electrode when required. We are just going to have to agree to disagree on this subject because you are just not getting what I'm talking about. I would ask that when you feel like just maybe I have a point you conduct a little test for yourself. It has been interesting bantering with you. I'm in MD. if the soil in your area is better great. Apperantly the soil were the original poster lives isn't though. I wonder how much resistance he has there? Most likley poor.

I never said I could achieve 25 ohms with one rod, I pointed out that the NEC doesn't require two as a blanket statement.

So let me ask you, would you be able to acheive 25 ohms in your area by driving the second rod?

If so, would this 25 ohms be consistant across say 100 feet of earth between the POCO's pole and the service to a house?

Would it be more like 100 ohms or higher?

BTW, welcome to the forums.

Roger

 

[sparkygriffin]

Now were getting somewhere. If you agree that one ground rod isn't going to be enough than his house was not meeting the NEC. So would you than agree that if it did he may not have expeireneced the problems he had? That was my point go back and check. I always said he had to have a good grounding system, just like the PO.CO. said. And thank you for the warm welcome.