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Thread: Ideal dock wiring Questions?

  1. #31

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    Quote Originally Posted by jwelectric View Post
    Ballvalve

    The equipotential bonding grid is different than the grounding electrode such as being discussed here although what Randyj is describing with his ground rods at the pier is almost a equipotential grounding grid.

    It is his conception that the branch circuit supplying the pier is somehow losing current to earth that is wrong.
    You got pretty close there JW but I'm not saying that the circuit supplying power to the pier is losing current to earth. I'm saying that it loses voltage due to the distance from the switch box panel. If the ground wire comes all the way from the switch box hundreds of feet away there is a difference in voltage between the ends of that ground wire and a difference between that ground wire and the ground rod at that distance. This is why that ground wire back to the main switch panel must be cut and a ground rod installed at the walkway entrance. If this is not done then there is a very measureable voltage between the dock and the water. I have in fact touched one lead of my volt meter to a dock then dropped the other end in the water and got an 8 volt reading but when I disconnected the ground wire going back to the switch box panel the reading dropped to zero. The ground rod configuration may or may not protect equipment/appliances and may not even throw a breaker but it will save lives because the current path is then through the metal dock bonded to the ground rod. I may not understand the description of equipotential grounding but I do understand zero voltage and zero current and I know how to detect them.

  2. #32
    Engineer Furd's Avatar
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    I'm reminded of a few old sayings like, "You can lead a horse to water..." and, "There are none so blind as those that refuse to see." Keep up the good work, JW.

    Randy, there are all manner of "electrical inspectors" and some are not worth the powder to blow them to hell. I would be VERY leery of any contractor that was also authorized to do inspections. I once dealt with a municipal inspector that couldn't have found any code citations if he was given the book opened to the correct page. It isn't unlike doctors that send you to an imaging center in which they have a financial stake. The "inspector" that required you to disconnect the grounding electrode conductor from the metallic water piping was WRONG! Now to give benefit of doubt it may be possible that he wanted you to upgrade the GEC rather than completely remove it and then failed to inspect the entire system on the re-inspection...if there WAS a re-inspection.

  3. #33
    Electrical Contractor/Instructor jwelectric's Avatar
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    Quote Originally Posted by Randyj View Post
    You got pretty close there JW but I'm not saying that the circuit supplying power to the pier is losing current to earth. I'm saying that it loses voltage due to the distance from the switch box panel. If the ground wire comes all the way from the switch box hundreds of feet away there is a difference in voltage between the ends of that ground wire and a difference between that ground wire and the ground rod at that distance.
    In 44 years of field experience, 11 years of classroom experience, 4 years of college training, the one thing I have never seen nor heard tell of until your post is a grounding conductor that has a difference in voltage between the ends if the conductor. As a matter of fact I have never seen a grounding conductor that had voltage on it unless there was a fault condition.
    Please explain what kind of grounding wire you have that carries a difference in voltage between the two ends.

    Quote Originally Posted by Randyj View Post
    This is why that ground wire back to the main switch panel must be cut and a ground rod installed at the walkway entrance. If this is not done then there is a very measureable voltage between the dock and the water.
    Let me make sure that I understand just what you are saying here. You cut the grounding conductor and drive a ground rod to which you attach the equipment grounding conductor and all faulted current then flows into earth, is this correct so far????

    Quote Originally Posted by Randyj View Post
    I have in fact touched one lead of my volt meter to a dock then dropped the other end in the water and got an 8 volt reading but when I disconnected the ground wire going back to the switch box panel the reading dropped to zero.
    Now was this before you installed the ground rod or after you installed your ground rod?

    Quote Originally Posted by Randyj View Post
    The ground rod configuration may or may not protect equipment/appliances and may not even throw a breaker but it will save lives because the current path is then through the metal dock bonded to the ground rod.
    and this is nothing short of bull droppings. These ground rods does not save any lives at all and in fact puts lives in danger

    Quote Originally Posted by Randyj View Post
    I may not understand the description of equipotential grounding but I do understand zero voltage and zero current and I know how to detect them.
    It is very obvious that you do not have any understanding of grounding and bonding at all. If you are going to try to convince me that by removing a grounding conductor from the systemís grounding electrode and it removed fault current to the water you are going to have to do a lot better job than you have done here.

  4. #34
    General Engineering Contractor ballvalve's Avatar
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    The OP said a few people a year die from shocks at this lake. Seems thats like having a serial killer in the neighborhood, and someone would have done a 'study' as to its causes.

    I have never worked on a dock and hardly been on one, but I fail to see why this is any different than a pool deck or waterscaped yard with lights and pumps and outlets - except that its always in motion.

    Such areas utilize GFCI's and normal grounding wires, and no one in planning or in the trades has ever suggested they have a equipotential ground plane installed. I think you mentioned 3x3 feet.

    And RAJ, surely no one would consider the 'voltage drop' contributing to shocks and breaking the ground wire at the dock foot and adding ground rods. Thats a bit of hallucination.

    I would guess your serial killer at the lake is old wiring that has wiggled up and down for many years in waves and storms and rubbed itself bare in conduit, to various values of danger. Attached to old standard breakers, perhaps without any ground at all.

    I would wire my dock with some mine rated SJ 3 or 4 wire cord in pvc conduit with pvc flex and loops at the dock joints connected to modern GFCI breakers. Then I would liberally use silicone inside the boxes to partially encapsulate the wires to preclude motion. And all connections would be covered with an anti corrosive paste-grease.

    A lot of work, which is why I dont have a dock and why people die at them.

    Frankly, a standard extension cord zip tied to the dock rail and plugged into a GFCI would likely be safer than some old wires in flex or conduit that cannot be inspected for chaffing from motion. Ask Boeing, they worked this out years ago.
    Last edited by ballvalve; 03-23-2011 at 11:10 PM.

  5. #35
    Electrical Contractor/Instructor jwelectric's Avatar
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    Ballvalve

    Any and all bodies of water, be it pool, pond, lake or fountain requires an equipotential bonding grid. Even the whirlpool tub installed in bathrooms requires bonding of any metal pipes that are in contact with the tub water.

    Each and every one of these bodies of water will require an insulated equipment grounding conductor to be installed all the way back to the service equipment except that portion of the circuit that is inside a dwelling unit.

  6. #36
    General Engineering Contractor ballvalve's Avatar
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    From what I have seen, no inspector has ever uttered the word equipotential bonding grid at a pool [especially an above ground pool] or yard fountain. Of course they will require a ground wire. Have not seen it spec'd into plans either, on a residential level. Seems to have variable regional enforcement based on web research.

    Bonding pipes at a whirlpool tub does not seem to be related to EPB grids.

    And how do we account for the millions of portable hot tubs that have only GFCI's and a standard plug?

    What are the 'mechanics' of these dock deaths? Is it the motion that causes shorts?

    http://www.erico.com/public/library/fep/LT1242.pdf

    At this site, they claim even above ground pools need a perimeter EPB grid around it. Anyone ever seen that installed?

    If the OP ever comes back after being tossed to the lions, I would like to know the details of these regular dock deaths.
    Last edited by ballvalve; 03-24-2011 at 11:52 AM.

  7. #37
    Electrical Contractor/Instructor jwelectric's Avatar
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    680.26 requires the equipotential bonding grid for in ground pools

    680.42 for hot tubs installed outside but there is a TIA out for these installations

    680.74 for the whirlpool tub which must be bonded with a #8 just as any equipotential grid

    682.31 for the insulated EGC and 682.33 for the equipotential bonding grid for natural
    or artificially made bodies of water which the pier would fall under.

    Sorry that you have never heard of them but they are a very important component to wiring around bodies of water where someone is going to come in contact with the water and metal objects at the same time.

    As to the OP I would be inclined to say that instead of him being tossed he jumped in on purpose.

  8. #38
    General Engineering Contractor ballvalve's Avatar
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    I said that I never saw them spec'd in on residential plans, not that I have not heard of them.

    It appears that many consider them foolish or ineffectual at best.

    Could you answer my question as to what is the practical answer to the mechanics of dock electrocutions? Am I correct in assuming that a dock in motion is prone to compromising wire insulation?

    Obviously, if the NEC were the bible, you would be in a top post at the Vatican research library. But as you know, each religion has its own flavor of bible.

    Some of us just need practical answers without page and paragraph quotes if we are to help you actuate the 'death and electricity' sticky to save lives.

  9. #39

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    Looks like we're gonna beat this horse to death. I can tell you that I learn a heck of a lot about things from people who know a heck of a lot less about them than I do. I NEVER have claimed to have all that education in electricity nor to teach it or all those other wonderful things. But I do know a few things about it and learned it by experience and OJT and have worked in a multitude of different kinds of residential, commercial, and institutional maintenance. I couldn't begin to tell you much about 3 phase wiring but I've worked on lots of 3 phase equipment. I've been around delta wye's and worked on 440 volt vacuum forming machines but can't tell you how a delta wye is configured or how that electricty comes out of it... but I can find a broken wire and replace a burned out element, switches and all kinds of things that run on 440 on a vacuum forming machine and have done lots of maintenance on cad/cam's and CNC's but still can't operate either.
    I can tell you that offshore equipment and boat docks are far from the same as residential wiring. They have special and abnormal issues from earth bound structures. If you're gonna get to know something about dock wiring you need to read this...
    http://www.highport.com/electricalHazard.php
    Here is an except from it....It is worth repeating that shore-power based AC circuits never have the neutral grounded on board...

    NEVER think you know more about something because you have more notches in your belt.... I'm the first to tell you I don't know everything and can learn from any body. If I knew it all then I would have never come to this forum to ask questions.... I have learned that marine electricity is not the same as terrestrial electricity. And yes, two ground rods hundreds of feet apart can have voltage and current between them and not even be connected to a power source. This is not class room stuff. It is field experience. There's still lots I don't know.

  10. #40

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    Quote Originally Posted by ballvalve View Post
    The OP said a few people a year die from shocks at this lake. Seems thats like having a serial killer in the neighborhood, and someone would have done a 'study' as to its causes.

    I have never worked on a dock and hardly been on one, but I fail to see why this is any different than a pool deck or waterscaped yard with lights and pumps and outlets - except that its always in motion.

    Such areas utilize GFCI's and normal grounding wires, and no one in planning or in the trades has ever suggested they have a equipotential ground plane installed. I think you mentioned 3x3 feet.

    And RAJ, surely no one would consider the 'voltage drop' contributing to shocks and breaking the ground wire at the dock foot and adding ground rods. Thats a bit of hallucination.

    I would guess your serial killer at the lake is old wiring that has wiggled up and down for many years in waves and storms and rubbed itself bare in conduit, to various values of danger. Attached to old standard breakers, perhaps without any ground at all.

    I would wire my dock with some mine rated SJ 3 or 4 wire cord in pvc conduit with pvc flex and loops at the dock joints connected to modern GFCI breakers. Then I would liberally use silicone inside the boxes to partially encapsulate the wires to preclude motion. And all connections would be covered with an anti corrosive paste-grease.

    A lot of work, which is why I dont have a dock and why people die at them.

    Frankly, a standard extension cord zip tied to the dock rail and plugged into a GFCI would likely be safer than some old wires in flex or conduit that cannot be inspected for chaffing from motion. Ask Boeing, they worked this out years ago.
    Ballvalve...et.al. Here's another link that discusses the exact same thing and in this discussion a "qualified" electrician is saying the very same thing about the tingle that I said way back there concerning voltage drop.
    ://www.electrical-contractor.net/forums/ubbthreads.php/topics/167411/2.html
    Here's the part that I noticed in the thread...
    Quote:
    With the mains to the house, garage and dock off I still have the same current flow, yet neither the new copper ground rod at the meter, nor the poco ground, nor their guy wire show any current flow.

    Did you remove the main bonding jumper for this test? The utility primary and secondary grounded conductors are connected together. In many cases like this the source of the voltage is the voltage drop on the utility primary neutral.
    Don
    _________________________
    Don(resqcapt19)

    As for some details on the electrocutions on this lake I would say that most have been due to frayed wires as you described. I know one was a construction worker who dropped his saw in the water and he automatically reflexed to get it. One had something to do with some idiot had a hot tub on his dock when 240 volts came through the dock into the water via a swimmer who grabbed the metal dock. I would bet that the dock was not grounded properly to a ground rod. To me the key here is that electricity does not take the shortest path to source but takes the path of least resistance. From what I've read the NEC is somewhat at conflict with applications in non-conforming locations. Personally, I live on the lake but don't even have a dock and if I did I would rather it not be wired for electricity but still would have a ground rod bonded to it. This would be to prevent shock to swimmers in the event someone used an extension cord for a battery charger, light, or any other appliance.
    The idea that there's no such thing as voltage leaks is just wrong. There is no such thing as an absolute insulator. All an insulator does is offer a very good or acceptable amount of resistance. If glass and ceramics (very good insulators) did not conduct electricity then we would not have resistors and transistors, i.e. they leak electricity. In a sense even rubber is a very good conductor of electricity if you remember the old experiment with static electricity and pocket combs... and that Tesla thingy with the big rubber band can give you a hell of a few thousand volts shock.
    You'd be surprised at how many docks I've seen with no more protection than ordinary house wiring and far worse. Read the links I've posted concerning docks. I may get some terms wrong or confuse current and voltage but the detail is not in the current/voltage from the distribution point. The important item is in the ground to the dock. The voltage drop causing the tickle is from the losses due to the distance these wires travel, (especially if the earth ground wire goes hundreds of feet back to the switch box. Suppose this were dc. An electron would have to travel from the battery on the "hot" all the way back down the neutral wire to the panel where earth ground is connected then back down the "ground wire" to the dock. It would have to travel 3 times the distance as it would on only a single wire. This difference in travel time and the losses due to whatever causes those losses... I'll call it friction as an analogy to a mechanical device... would result in a difference in potential or current or whatever the correct term is. This results in a measurable difference in voltage just as I have proven to myself when I put one lead of my volt meter in the water and touched the other to the dock I worked on. For all I know it could have been differences due to stray voltages between the dock and distribution panel but the fact is that there was a voltage difference and I've seen it and heard of this several times. I am not new at this.) The "voltage drop" I'm seeing is in the earth ground wire when it goes back to the panel, not the wires carrying the service voltage/current to and from the dock.
    At the dock the potential will be different than it will be at the other end. I can only explain this in layman's terms because I am not accustomed to the technical jargon. See the link I posted to the electrical-contractor.net thread. It is a very "techy" discussion. I have to strain a little to follow but I do understand it.
    Last edited by Randyj; 03-25-2011 at 01:40 AM.

  11. #41
    Electrical Contractor/Instructor jwelectric's Avatar
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    Randy

    What Don, Mike Holt, and the IEEE paper to which you have posted links are talking about current imposed on earth by the utility company. If we use the requirement found in 250.56 of the NEC of 25 ohms, which is far more than the NESE will allow the power companies to have, and their primary voltage at most residential transformers of 7200 volts we can easily see that the power company can send 288 amps through earth all day long. This is the “stray voltage” they are talking about.

    Where you are misguided at is in your thinking that electricity somehow runs to ground or earth. This is the thinking of someone who works on auto electrical systems a lot, “if the ground ain’t hooked up it won’t work” Well my friend a car is not connected to earth but your thinking should I connect the negative post to earth and my radio to earth the radio should play with only one (positive) wire connected to the battery.
    If this were true I could connect one side of a battery to the bare copper wire at my meter and the battery would go dead. The battery will not go dead at all nor will 120 volts run into earth either. Should I drive a ground rod in the center of my yard and connect one side of a keyless to the rod and the other to a breaker in the panel the light would not come on but using your theory the light should come on.

    The fault current path provided by the equipment grounding conductor that you are cutting is what opens the overcurrent device be it fuse or breaker. Once you cut this equipment grounding conductor and drive a ground rod you are now putting more current through earth that it normally would have or you are putting the person in the water at more risk of death.

    If you doubt me then send an email to any of those to which you have posted a link and invite them to this thread or just tell them what you are doing and ask them for their opinion. Or to hit a little closer to home contact these people and ask them
    ALABAMA ELECTRICAL CONTRACTORS LICENSING BOARD
    610 South McDonough Street
    Montgomery, AL 36104
    334-269-9990 By the way I have contacted someone in this department with information obtained from this thread in hopes of getting some attention brought to the issue.
    Go over to the Mike Holt web site and join, be sure to tell them you are an electrician or they will ban you, where Don is a member and tell them what you are doing. Go to The Electrical Guru web site and post your methods. Go to any site dedicated to the electrical professional and post your method. Then come back and let us know what they had to say.
    I do believe in my heart that you believe that what you are doing is a good thing but please listen as not only me but others here are trying to tell you that what you are doing is wrong. Your concept of the earth ground is wrong and very dangerous; please stop till which time that you have a better understanding of what you are doing. Seek advice from professionals in your area and have them back their statements with code references.

  12. #42
    Electrical Contractor/Instructor jwelectric's Avatar
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  13. #43
    Electrical Contractor sbrn33's Avatar
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    Randy, please listen to JW and the others.
    YOU ARE GOING TO GET SOMEONE KILLED with your bull headed stance on this.

  14. #44
    DIYer, not in the trades LLigetfa's Avatar
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    While Randy has taken much of what I posted in this thread as cannon fodder to support his arguement, I cannot condone his stance of removing grounding and must side with code as JW cited. I live in Ontario, the land of 100,000 lakes. NorthWestern Ontario being part of the Laurentian Shield is mostly igneous rock and can be a bear to get good grounding. Years ago I worked on a project for Ontario Hydro where we were improving the grounding on the lattice towers of their transmission lines to reduce resistance to ground in order to better withstand lightning hits. On some towers we had to drive as many as 50 ground rods.

    A lot of people here have homes on the lake and the utlity neutral (ground) is less that desirable. People are losing electronic equipment to damage from power fluctuations on the neutral affected by ground loops. Sure, it would be the cheap and easy way out to just cut the gound, eliminating the loops but that's not to code.

    When I built my home, the electrical inspector insisted that I ground to my well casing. My boss at the time was an electrical engineer and I sought his advice. He advised me not to ground to the casing so I objected and asked for a code citation but got none. Of course, I also didn't get connected until I complied and ground to the well casing. My home is not on the lake and not on exposed bedrock.

    I work as a network engineer in an industrial setting and face ground potential difference often. I am constantly having to debate with electricians and electrical contractors, the merit and procedure of entrance protection, isolated ground receptacles, etc.

  15. #45

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    JW... I can assure you that I am not simply being bull headed. There is a reason for my stance on the grounding of boat docks. I may not be able to throw out NEC regulations and I may not be able to explain it in technical terms but apparently it is something unusual to people who are not familiar with this kind of application. Here's the link to the website where Alabama Power owns the lake. Check out the thread and you may see the logic better than I can explain it. If I'm wrong I want to know why because there are lots of linemen and electricians who are doing exactly as I do. Oddly, arguments and situations like this prompted me to get my plumbing license (I made 98% on my licensing exam). Maybe I'll end up with my electrician's license too.
    http://www.lakesonline.com/Forum/sho...8&SiteID=AL008
    Last edited by Randyj; 03-25-2011 at 09:58 AM.

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