Ow. on so many different levels...

[stickboy1375]

Could it be that ground rods were once long enough to reach the ground water table and that was the connection back to the source? But because of the recent weather conditions and global warming and the drought conditions, ground rods are no longer interconnected by the moisture that once was normal in the ground? By a lake I can see, but maybe the moisture content is not high enough to overcome the resistance and reach back to the source. Then there are the band aides like the GFCI's and changes in grounding and bonding. Why not make all mains GFCI protected and drop the individual branch circuits. (I can hear the pimply mfg internet rep choking on his diet coke)

Maybe there should be a code change to 10 foot long ground rods instead of 2 eight footers or, like utilities, drive 40 footers then maybe the lakes would get grounded.

Maybe the utilities should have to ground all the bodies of water, then there wouldn't be these ... accidents.

I do realize that phase to phase, a GFCI would be useless in this instance; but it might have had a better chance to fault out than a normal 220 breaker.

The earth won't clear a fault.

 

[hurk27]

Could it be that ground rods were once long enough to reach the ground water table and that was the connection back to the source? But because of the recent weather conditions and global warming and the drought conditions, ground rods are no longer interconnected by the moisture that once was normal in the ground? By a lake I can see, but maybe the moisture content is not high enough to overcome the resistance and reach back to the source. Then there are the band aides like the GFCI's and changes in grounding and bonding. Why not make all mains GFCI protected and drop the individual branch circuits. (I can hear the pimply mfg internet rep choking on his diet coke)

Maybe there should be a code change to 10 foot long ground rods instead of 2 eight footers or, like utilities, drive 40 footers then maybe the lakes would get grounded.

Maybe the utilities should have to ground all the bodies of water, then there wouldn't be these ... accidents.

I do realize that phase to phase, a GFCI would be useless in this instance; but it might have had a better chance to fault out than a normal 220 breaker.

Gunning
Here is a thread that I helped a member do some experiments a few years back he was in Houston in a very carbon rich soil area that had a very low ohms per cm reading, if you want to learn more about why I make the statement that ground rods are about useless, read that thread as it was an eye opener for many who did not understand how the connection of electrode to earth works.

Here is why even if you place a ground rod in water it will not really lower the resistance of this connection to earth very much and may increase the voltage drop in a much shorter distance from the electrified metal that the person receives a shock from placing a grater potential across the two points of contact:

It is not the Earth as a whole that is a bad conductor because we know that the Earth has many parallel paths and will always as a whole be a very low resistance and as some papers has pointed to it can be considered as having a 0 ohm impedance because of all the parallel paths run into infinity.

The reason we have a much higher resistance on a ground rod is because of the small area of Earth or soil that is around the rod or connection point, there is only so much soil that will come into contact with a rod and so little amount of soil in the area around the rod that there is less parallel paths to combine that would lower the resistance.

And this is why the shells around a rod have the largest voltage drop in the shell closest to the rod as shown in the graphic shown above. this holds true even if the ground rod is in water, for the same reason so very little water will be in contact with the rod, and the same reason that even in water the greatest voltage drop will be in the shells closest to the rod, apply a voltage to the rod in the water and you will have a very high voltage drop not that far from the rod, it is this voltage drop that is was gets people in the water because their body is at two different potentials in a very short distance, as you will read in the link above, these shells are smaller where you have a lower ohms per cm soil, water is no different, the more conductive of the water the smaller is the shell around the electrode which means a higher voltage drop across a shorter distance from the rod, salt water has a shell of about 9" where the voltage will drop 75% and you will have the same 90 volts between the rod and a point in the water 9" out from the rod, the difference is the actual resistance of the rod connection to earth will also be lower but in no way can ever be depended upon to operate any OCPD and should never be used as such.

 

[jumper]

A connection to earth is no where near a dead short. A typical ground rod will not trip a 20 amp breaker when you connect the hot wire to it. It is not grounding, but bonding that clears faults. You need a low impedance path back to the source, not to earth. In our grounded systems, that path is via the Equipment Grounding Conductor, to the main bonding jumper to the grounded conductor.

You need an effective fault clearing path. and effective connection to the earth does not do much to protect people from shock or to clear faults.

The earth won't clear a fault.

:thumbsup::thumbsup::thumbsup::thumbsup::thumbsup:

 

[jumper]

Gunning
Here is a thread that I helped a member do some experiments a few years back he was in Houston in a very carbon rich soil area that had a very low ohms per cm reading, if you want to learn more about why I make the statement that ground rods are about useless, read that thread as it was an eye opener for many who did not understand how the connection of electrode to earth works.

Here is why even if you place a ground rod in water it will not really lower the resistance of this connection to earth very much and may increase the voltage drop in a much shorter distance from the electrified metal that the person receives a shock from placing a grater potential across the two points of contact:

It is not the Earth as a whole that is a bad conductor because we know that the Earth has many parallel paths and will always as a whole be a very low resistance and as some papers has pointed to it can be considered as having a 0 ohm impedance because of all the parallel paths run into infinity.

The reason we have a much higher resistance on a ground rod is because of the small area of Earth or soil that is around the rod or connection point, there is only so much soil that will come into contact with a rod and so little amount of soil in the area around the rod that there is less parallel paths to combine that would lower the resistance.

And this is why the shells around a rod have the largest voltage drop in the shell closest to the rod as shown in the graphic shown above. this holds true even if the ground rod is in water, for the same reason so very little water will be in contact with the rod, and the same reason that even in water the greatest voltage drop will be in the shells closest to the rod, apply a voltage to the rod in the water and you will have a very high voltage drop not that far from the rod, it is this voltage drop that is was gets people in the water because their body is at two different potentials in a very short distance, as you will read in the link above, these shells are smaller where you have a lower ohms per cm soil, water is no different, the more conductive of the water the smaller is the shell around the electrode which means a higher voltage drop across a shorter distance from the rod, salt water has a shell of about 9" where the voltage will drop 75% and you will have the same 90 volts between the rod and a point in the water 9" out from the rod, the difference is the actual resistance of the rod connection to earth will also be lower but in no way can ever be depended upon to operate any OCPD and should never be used as such.

Well said.:thumbsup::thumbsup::thumbsup:

 

[stickboy1375]

Another pretty graphic.

 

[Flex]

Just read an article in the new ECM magazine forensic files about a similar situation. It was in the July 2010 issue, about a kid who was electrocuted swimming. Turned out to be a broken egc back to the panel according to the expert.

 

[texie]

Just read an article in the new ECM magazine forensic files about a similar situation. It was in the July 2010 issue, about a kid who was electrocuted swimming. Turned out to be a broken egc back to the panel according to the expert.

Here is a link to the article: http://ecmweb.com/design/case-floating-dock

 

[stickboy1375]

Here is a link to the article: http://ecmweb.com/design/case-floating-dock

A ground wire provides a safe return path to ground for any leakage or fault voltages. An internal motor short would result in tripping the circuit breaker, or leakage imbalance would trip the GFCI circuit. However, with the ground wire severed at the house, electricity could not flow on this wire. Therefore, there would not be a GFCI sensed voltage imbalance at the lift motor to trip the unit. Both GFCI circuits were on the up side of where the short to ground was located. Effectively, this said the GFCI became unusable as soon as the ground wire became severed.

Anybody agree with what I put in bold font?

 

[ritelec]

Thank you Don/Jumper !

 

[kwired]

Could it be that ground rods were once long enough to reach the ground water table and that was the connection back to the source? But because of the recent weather conditions and global warming and the drought conditions, ground rods are no longer interconnected by the moisture that once was normal in the ground? By a lake I can see, but maybe the moisture content is not high enough to overcome the resistance and reach back to the source. Then there are the band aides like the GFCI's and changes in grounding and bonding. Why not make all mains GFCI protected and drop the individual branch circuits. (I can hear the pimply mfg internet rep choking on his diet coke)

Maybe there should be a code change to 10 foot long ground rods instead of 2 eight footers or, like utilities, drive 40 footers then maybe the lakes would get grounded.

Maybe the utilities should have to ground all the bodies of water, then there wouldn't be these ... accidents.

I do realize that phase to phase, a GFCI would be useless in this instance; but it might have had a better chance to fault out than a normal 220 breaker.

I disagree about ground rods that reach the water table issue you bring up. Some areas have water table that is just a couple feet below surface, some areas the water table is above the surface (that is why there is a lake or stream there), and other places the water table may be 100 feet or more deep. Has nothing to do with global warming or anything like that - it has been this way since before man discovered this.

Gunning
Here is a thread that I helped a member do some experiments a few years back he was in Houston in a very carbon rich soil area that had a very low ohms per cm reading, if you want to learn more about why I make the statement that ground rods are about useless, read that thread as it was an eye opener for many who did not understand how the connection of electrode to earth works.

Here is why even if you place a ground rod in water it will not really lower the resistance of this connection to earth very much and may increase the voltage drop in a much shorter distance from the electrified metal that the person receives a shock from placing a grater potential across the two points of contact:

It is not the Earth as a whole that is a bad conductor because we know that the Earth has many parallel paths and will always as a whole be a very low resistance and as some papers has pointed to it can be considered as having a 0 ohm impedance because of all the parallel paths run into infinity.

The reason we have a much higher resistance on a ground rod is because of the small area of Earth or soil that is around the rod or connection point, there is only so much soil that will come into contact with a rod and so little amount of soil in the area around the rod that there is less parallel paths to combine that would lower the resistance.

And this is why the shells around a rod have the largest voltage drop in the shell closest to the rod as shown in the graphic shown above. this holds true even if the ground rod is in water, for the same reason so very little water will be in contact with the rod, and the same reason that even in water the greatest voltage drop will be in the shells closest to the rod, apply a voltage to the rod in the water and you will have a very high voltage drop not that far from the rod, it is this voltage drop that is was gets people in the water because their body is at two different potentials in a very short distance, as you will read in the link above, these shells are smaller where you have a lower ohms per cm soil, water is no different, the more conductive of the water the smaller is the shell around the electrode which means a higher voltage drop across a shorter distance from the rod, salt water has a shell of about 9" where the voltage will drop 75% and you will have the same 90 volts between the rod and a point in the water 9" out from the rod, the difference is the actual resistance of the rod connection to earth will also be lower but in no way can ever be depended upon to operate any OCPD and should never be used as such.

I don't remember but I think it was you that one time mentioned that the earth is an excellent conductor, but we have not come up with a practical way to make a low impedance connection to it, or something to that effect.

Anybody agree with what I put in bold font?

NO. GFCI does not require equipment grounding conductors to work, equipment grounding may enhance the operation of a GFCI. GFCI protection will not protect anyone from stray voltage that may be in an equipment grounding conductor - which is often the culprit in these marina settings even when GFCI protection is there. You can install everything to code and have a bad connection in the service neutral back at the house, cabin, lodge, etc cause a voltage rise in the equipment grounding conductor and a person in the water down at the dock is subjected to the voltage drop of that problem and gets electrocuted. It can and has happened and for the most part is nobody's fault according to current codes.

 

[hillbilly1]

Just read an article in the new ECM magazine forensic files about a similar situation. It was in the July 2010 issue, about a kid who was electrocuted swimming. Turned out to be a broken egc back to the panel according to the expert.

You have to take those articles with a grain of salt, because I know the details of one of those, and it could not have happened the way it was stated, but any way, a short or leakage to ground regardless of the EGC connection would trip a functioning gfi, IF it is on the load side of the gfi, BUT if the leakage is on the line side, and the EGC is severed, it can energize the unbonded metal dock and not trip the gfi.

 

[Article 90.1]

Ok, a few updates as promised:
http://www.wbir.com/news/local/story.aspx?storyid=226620
http://www.knoxnews.com/news/2012/jul/14/state-finds-electrical-issues-at-bean-station

The TN Electrical Inspectors Report (this is just a report that is separate from the investigation by TWRA).
http://www.wbir.com/pdf/071312_marina_safety.pdf

Still a very sad situation no matter what any report finds. One thing that I find disturbing is that the inspectors and the utility don't cease the service of electricity immediately and instead gig the property owner a 30 day window to make the necessary repairs.

I do hope that after the lawyers get through this case that TN will wake up and revamp its permitting, inspection, and codes enforcement laws, policies, and procedures.

 

[kwired]

The general public sees 20 violations and assumes this place is involved in downright criminal activity. Truth is you can go to many places and find 20 violations easily. The focus needs to be on what exactly caused the voltage that resulted in the accident, and keep all the other minor stuff out of public reports. I really doubt that a missing filler plate in a breaker panel had anything to do with the accident, but still should be corrected.

 

[Fulthrotl]

The general public sees 20 violations and assumes this place is involved in downright criminal activity. Truth is you can go to many places and find 20 violations easily. The focus needs to be on what exactly caused the voltage that resulted in the accident, and keep all the other minor stuff out of public reports. I really doubt that a missing filler plate in a breaker panel had anything to do with the accident, but still should be corrected.

yeah, and it could have been someone with a genset on a boat nearby.....
but i've worked on marinas, and usually they are pretty sucky on the
install...

it is interesting that no mention was made of GFCI devices at all.

"there is no groundwire pulled from shore to marina....."

and specific mention was made of 555.9... splices and taps....

"555.9 Electrical Connections.
Electrical connections shall be located at least 305 mm (12 in.)
above the deck of a floating pier. Conductor splices, within
approved junction boxes, utilizing sealed wire connector
systems listed and identified for submersion shall be permitted
where located above the waterline but below the electrical datum
plane for floating piers. All electrical connections shall be located
at least 305 mm (12 in.) above the deck of a fixed pier but not
below the electrical datum plane."

thanks for taking the time to post a followup, 90.1

 

[Little Bill]

It's sad that they chose an electrician (HVAC, plumbing, electrical) to explain the violations when he obviously doesn't understand grounding/bonding. Or at least not well enough or didn't explain it well. Most of the "combo HVAC, Plumbing" electricians that I know of, know just enough to choose the right size wire for an HVAC install. I'm not grouping all into this catagory, just the ones I know of.

"Grounding" protects people from electrocution by allowing energy to escape to the earth if the feeder accidentally becomes charged and someone touches it.

 

[stickboy1375]

It's sad that they chose an electrician (HVAC, plumbing, electrical) to explain the violations when he obviously doesn't understand grounding/bonding. Or at least not well enough or didn't explain it well. Most of the "combo HVAC, Plumbing" electricians that I know of, know just enough to choose the right size wire for an HVAC install. I'm not grouping all into this catagory, just the ones I know of.

After I read the article, I too shook my head as to what was said...

 

[kwired]

It's sad that they chose an electrician (HVAC, plumbing, electrical) to explain the violations when he obviously doesn't understand grounding/bonding. Or at least not well enough or didn't explain it well. Most of the "combo HVAC, Plumbing" electricians that I know of, know just enough to choose the right size wire for an HVAC install. I'm not grouping all into this catagory, just the ones I know of.

After I read the article, I too shook my head as to what was said...

What we don't know is if that is actually what he thinks or if he was just trying to say something that non electrical professionals might understand.

If he is brought in to a court to testify and can only come up with statements like he made he will not be any help a good opposing attorney along with a good expert can tear down his credibility as an expert easily.

 

[stickboy1375]

What we don't know is if that is actually what he thinks or if he was just trying to say something that non electrical professionals might understand.

If he is brought in to a court to testify and can only come up with statements like he made he will not be any help a good opposing attorney along with a good expert can tear down his credibility as an expert easily.

These articles are written for the electrician in mind, so I don't get why they are so hacked with poor information.