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Stray Voltage in North Carolina Part 2 of 3


Mike,

I spoke to you earlier this year about the problem. The Co-op will do nothing to get rid of the Neutral to Earth Ground Voltage on our neighborhood power distribution. I even have 5 volts on my natural gas pipes.

Thanks, Lonn Rickstrom
Lonn.Rickstrom@gdc4s.com

Mike Holt's Comment: Lonn, if the utility has provided a neutral isolator that separates the primary neutral voltage (stray voltage) from your home, they should be off the hook. But, you need to have the phone and CATV isolated also, but this might be a problem, since the NEC requires them to be grounded (actually bonded) to the building grounding electrode system.

Lonn's Comment: Mike, initially the utility installed a Ronk Stray Voltage Blocker, but as you said it did not do any good, as the cable and phone shield connected the elevated primary neutral voltage back to my pool. Now the utility says the elevated neutral voltage, as much as 5V (some call stray voltage) is normal and there is no problem and told me that I'm wasting the co-op member's resources.

Initially the pool handrail was not bonded and we got shocked when we were in the pool (5V) and we touched the handrail (0V). Now that the handrail is properly bonded to the pool steel structure, we don't get shocked in the pool any more. However, the pool handrail is now as much as 5V (because it's bonded to the pool steel structure). Now we get shocked when we stand on the wet deck (0V) and touch the 5V handrail (see photo above).

Mike Holt's Comment: Yep, that's the way elevated primary neutral-to-earth voltage works. Now all you need to do is remove the concrete deck around your pool (since it does not have any steel), replace it with a new deck with steel and attach the steel to the pool structure steel so that the new deck becomes 5V as well. This way there won't be a difference of potential (voltage) between the pool handrail (5V) and the new deck (5V). Just be aware, that you'll never be able to get rid of the elevated primary neutral voltage (only the utility can), no matter what you do. But you can mask it by energizing everything you touch by bonding all parts together!

Response from Lonn: Mike I have attached a few letters on this issue, could you give me some feedback for each?

Letter from Marvin Hamilton (electrical inspector) to you. Click Here [PDF Document]

Mike Holt: Mr. Hamilton used the wrong words to describe your problem. He used the term "fault current" and he should have used "neutral current or as some call it "stray current." However, he is almost correct in his statements that "the utility needs to better ground their transformers." He is correct, if the voltage from your pool handrail is 5V and it does not go away when your main breaker is opened, then this voltage orginates from the electric utility.

Letter from Tracy Bensely P.E (utility engineer) to Mr. Hamilton (electrical inspector). Click Here [PDF Document]

Mike Holt: Mr. Bensely response to the electrical inspector letter is correct. The neutral and earth are used together as the primary neutral conductor (called multipoint-ground neutral system), and the system is most likely effectively grounded for fault current. This means that a ground fault from a phase conductor to earth or neutral should be cleared. But remember the utility engineer was responding to the inspectors' letter about fault current, when the issue is elevated neutral-to-earth voltage (stray voltage).

Mr. Bensely is also correct when he says, "An inevitable result of this type of system [multipoint grounded neutral system] is a low level of "earth current" passing from the electrical equipment through the earth [on it's way back to the utility transformer].

When the impedance of the utility return neutral path (earth and neutral conductor) increases (summer and ground get dry and/or the neutral starts to fail), you have elevated primary neutral-to-earth voltage. This would not be too bad, but since the primary neutral is bonded to the secondary neutral, and the secondary neutral is required to be bonded to the service disconnect by the NEC [250.24(A)], you now have elevated primary neutral-to-earth voltage on all metal parts of your home.

What I find is interesting is that utility engineer recognizes that the electrical inspector is not an expert in this field, so he poses six questions that he know the inspector can't possibly answer. What I would like to see is Mr. Bensely's answers questions No. 2 through 6 that he posed to the inspector!

I understand that the electrical inspector was demoted because of his letter. Let me know if there is anything I can do to help clear up his name. Maybe he used the wrong choice of words in his letter, but he was correct in that this appears to be a utility related problem.

Letter from Lonn Rickstrom (homeowner) to Tracy Bensely P.E (utility engineer). Click Here [Word™ Document]

Mike Holt: Lonn, it appears that your problem is related to elevated primary neutral-to-earth voltage (what some call stray voltage or stray current) and this is directly related to the maintenance of the primary utility neutral conductor by the utility and the system design, or unbalanced current on the utility primary neutral.

Elevated primary neutral-to-earth voltage on metal parts occurs when the primary neutral conductor has excessive impedance (poor or loose neutral connections), improper grounding (not as many ground rods as they should), and/or unbalanced neutral current from their multiwire system.

This problem of elevated primary neutral-to-earth voltage (stray voltage) is inherent in the multipoint grounding system when any of the above factors occur, just like the utility engineer stated in his letter.

What can the utility do? They need to download "Stray Voltage Troubleshooting Tips for Electric Utility [Word™] [PDF]" from my website so that can learn how they can fix their primary neutral conductor or hire an expert who can help them with this. But this is not likely to occur. You are only one customer complaining out of thousands and few utilities will incur the cost to solve your problem.

You are so right when you said "when power is turned off to my house I should not get shocked in my pool" We live in an amazing country and one would expect that the power delivered to your home would not shock you no matter what.

Neutral-to-earth voltage map. Click Here [Power Point File]

Mike Holt: I really don't have any comment on this.

Mike Holt's Comment: If you want more information about stray voltage (elevated primary neutral-to-earth voltage), click on the following links that are posted on my Stray Voltage Website.


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