Mutual Induction......Can't we All just get along.

Although relatively small, wouldn't this represent a "load" on the Transmission line?

Related to this......an AC megger (as opposed to a DC megger) must be used when testing parallel bussbar runs.

Thank you.

A qualification on the earth's capacitance: Capacitance is relative. What is meant is the earth's capacitance and atmospheric capacitance relationship. the cloud is charged relative to the earth. Both the earth and the cloud can hold a relative excess charge. A field is not radiation. do you believe you receive radiation from a magnet? EMR consists of two fields and is radiation because is energy.

2.18.08 We performed a service call today at a RV park in Florida that had a service pedestal that we had diagnosed as a lost neutral since the symptoms were 245volts phase to phase, 208V phase A to neutral, 47V phase b to neutral, The customer complained that the lights were fluctuating in brightness and their microwave, phone answering machine, TV, DVD player, GFI circuit, refrigerator all had stopped working. FPL confirmed a lost neutral and temporarily installed a neutral conductor from the service handhole to the nearby pad mounted transformer. This park has had multiple failures of direct buried aluminum conductors that have been in the ground for over 20 years. Brighthouse also came out today and removed about 40 feet of RG6 that the black jacket was partially melted and also replaced an amplifier. This RG6 cable braided shield apparently became the neutral path causing this cable to draw current and in turn heated the jacket melting the jacket.

Mike,I request one clarification:Is there any code violation [against NESC,NEC etc] involved here that to this 'mystery current'?Thanks.

There is good discussion of this situation in the following thread on Mike Holt's Forum:

http://forums.mikeholt.com/showthread.php?t=94966

if that doesn't work as a link, copy it and paste it in your browser window.

I would hope someone can give some more data because there are serious reservations about this situation along theoretical lines. Could this actually happen as stated?

All I have to say about this is: that would make you bang your head on that brick wall for a while.:)

POINTS TO REMEMBER(from the author)

1.There were over 100 houses exposed to this high induced current condition(not just the 1 in the picture).

2.The utility had measured this high current condition approx. 1 year earlier.

3.This same electrical arcing condition could be occurring inside all these homes(between the TV cable/converrter/amplifier etc. and the AC power ground).Anyone of these homes could have caught fire inside at any time.

4.As professional engineers,upon discovering this problem , A. we immediately ordered the cable systems be disconnected(to break this current loop) B. notified the head of the local electrical safety group. C. co-ordinated an emergency site meeting the next day

Approx. 2 days later a remedial solution was implemented.

I had someone with well water who lost his service neutral due to the Tree Root Circuit Breaker Method. Still cannot figure out how the CATV cable did not burn up. Maybe here in Ohio they use some type of shield capacitor that conducts very little 60 cycle juice through the shield but does conduct radio frequencies.

FYI - They seemed to have removed this article from their website...

http://www.powerlinesystems.ca/documentation/CaseStudy_Sept07_MysteryCurrent.pdf

This is part of an intriqueing study I've followed for many years.

I see that other Electricians have read the article on ground currents.

What is that URL? ------------------------

The URL hyperlink on the page is not working, after several days of checking.

080123W File Not Found Error 404

mike, here in the west, farmers have fought with the utilities for years over right of way under power lines. The farmers would loop cables under high voltage power lines to get enough power to run thier irrigation pumps. Now the power companies(Idaho and Rocky Mountain Power prosecute for trespassing on thier right of way.

I investigated a similar but more serious situation where the cable service boxes on the exterior of the houses were actually igniting vinyl and wood siding from heat generated. After determining that all of the houses in question were served by the same pad mounted single phase transformer a little diagramming presented the reason. The transformer lost its center tapped ground. When a large 120 volt load like the burner on a stove was presented to the system, it searched for a ground and found it in the cable TV shield and ground. Apparently many of the service grounds for the houses were high resistance (or at least higher than the cable ground) Some were bonded to water pipes and had no. 6 copper to driven grounds. The cable service had it's own driven ground at the cable terminal at the street. The first clue was that the cable shield to some of the cable services from the cable terminal to the houses was damaged and the cable terminal itself was damaged in addition to the cable service boxes at the houses.

This could have been complicated by the fact that the induced voltage/current is proportional to the current in the 230kV line. If the line serves typical cyclic loads, the induced and current would vary in a daily cycle. In fact, at some times, depending on the utility network, the line current could be zero, making chasing down the cause impossible. Good reminded to keep your eyes open.

That is fantastic, it reminds me how the farmers used to steal power from the utility companies with high tension lines over their properties. Keep winding copper until you get the voltage you want. Excellent find

"Directly behind these houses, was a 230 KV. high voltage transmission line corridor"

Since when are 230, 000 volt transmission lines and family dwellings being placed near one an other?

Oh, they have a problem with induced current-who would have thunk it?

The Fluke Voltage Probe relies on inductive pickup. But many times a voltage warning is also inductive pickup. I have had wires disconnected at the panel and got a warning. So my probe is always followed by my meter on the circuit of interest. If the probe triggers low side at 90 volts it can show a potential for a nasty shock or death from induced current. Most of Albuquerque is Groundless in the buildings.

I experienced a similar problem, but the problem happened during any ice storm. The ice storm and falling trees caused 240 volts to travel on the neutral side of the panel. This reflects on the grounding and bonding issue of video, data, and voicerequired by the NEC and TIA Codes. A faulty neutral at the panel and meter would cause over voltage on the ground conductors and cause splitters to spark.

Interesting article!

Maybe two years back, one of my regular customers had me add a new circuit / receptacle to his data processing center. Since this was being added to an already packed room, I used MC, rather than my preferred pipe. When time came to make my connections at the panel, I went to attach the ground wire first .... and was quire surprised to see a spark! That day, I was able to replicate this several times.

On a follow-up visit, I was not able to repeat my experience.

I did the 'original' wiring of this place, and I installed their massive UPS system. I still have no idea what was happening ... but the article confirms that I was not imagining things, and gives me some idea of how to run this down.

I wish there was a one-line showing where everything was after the modifications. I wonder if there is still ground currents flowing on the buildings electrical system as this was only about the induction between the cable and utility. It seems you would still have induction on all the other wiring systems. The guy had a 5ft loop and was getting 2A there has got to be other loops all over the place.

I fear problems from induced current from magnetic flux is more common than is reported. The question is, is it a health issue? I have found many of the older metal clad mobile homes had induced current from nearby high tension lines (765KV). For poorly grounded frames, you could arc it to earth. Bottom line, do not live anywhere near high voltage transmission lines.

Thanks Mike. This very thing happened a few months ago to a friend of mine. The CATV company went to hook up their line at his house and received a large jolt at their outdoor "D" mark termination. He then called me and said that the power was out in a good portion of his house. By the time I got there at the end of the day the POCO had just re-crimped their connections at the pole. I checked as many of the receptacles in his house as I could and found them to all be working properly. However, at that point in time any appliance that was on or had a digital display prior to POCO's arrival was burnt out due to the loss of the neutral.

File Not Found error 404

I worked for a cable company for two weeks when business was real slow and found 7 amps at 90VAC when I tried to hook the pole feed to the inside wiring. The TV was on one side and the pole current was on the other side of a Delta 240V xformer. There was a phone line(broken) laying on the xformer and draped on the cable hardline inducing voltage into the cable shield. The TV had a power supply short to the internal main board ground plane energizing the shield of the inside cable. As my Navy instructors said "Electricity is all FM, F*****G MAGIC"

Thanks Mike & Crew for keeping the industry abrest of things we need to know of out there. I run into stuff like this & know there's a cause but just work around it, not enough time. I sure learned a lot from your grounding & bounding class along these lines.

Very interesting! A head scratcher solved by good troubleshooting!

Must have been some arm twisting to get everyone working together for this one. That is usually the hardest part - everyone just wants to point the finger at someone else.

I would like to know the reason(s), technical or non technical, why a motor operating at 600Volt, three phase, is actually nameplated rated at 575 Volts, since the nameplate @ 575 Volt comes from UL and/or CSA standards.

Is the reason, say, because 575 Volt is between the upper limit of 600 Volt and the bottom limit of 550 Volt?

If anyone can provide an explanation, this would be appreciated. Thanks.

Regards, Vince Cimino Toronto, Canada

Hi Mike thanks again for doing such a good job on training you are the best , I just love this picture show what we don't know about current flow , it remain me of the show you had on water pipe current flow how a house with no electric wires connecting could start a electrical fire such a good film you are the best in training , I use your books in my classes Just to let you know I had a student Thomas Eritano pass your basic electrical theory book in six weeks and had a averge grade of 98 % best ever. John Hall electrical instructor . Ohio John Hall,