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  1. #11
    Join Date
    Nov 2011
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    9

    Default Re: neutral grounding @ pole??

    Here's an opinion from an electrical utility tech. The pole ground and the grounded neutral are there to clear a ground fault AT THE TRANSFORMER. A ground fault needs to have a low impedance path back to neutral to blow a primary (7200) fuse. It has nothing at all to do with the GEC and bonding at the service entrance panel. If no local GEC/Bonding system exists, any ground fault of the customer equipment could create a difference in potential between the customer equipment and ground due to the high resistance path back to the pole ground. This has caused more than one fatality. The ground rod itself is there to reduce the effects of lightning or other possible high voltage faults. Bonding 1s there to reduce differences in potential between grouded components during a ground fault. The main bonding jumper at the service disconnect assures that any ground faults on a branch circuit will have a sufficient current level to trip the associated breaker. Just my humble opinion.

  2. #12
    Join Date
    Dec 2007
    Location
    Tennessee
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    1,745

    Default Re: neutral grounding @ pole??

    In addition to what meternerd said, most transformers have a lightening arrester mounted to the primary bushing. It needs this ground to energize the arrester. Without it, the lightening is likely to hit both the hot and neutral wires, energizing both to the same voltage with very little difference of potential between them. The neutral (return) wire will remain energized until the surge finds ground.

    Why doesn't the utility use a copper clad steel instead of all copper for the ground? It would work as well, cost less and be unattractive to the copper thieves.

  3. #13
    Join Date
    May 2008
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    Pacific Northwet
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    1,627

    Default Re: neutral grounding @ pole??

    Quote Originally Posted by keith3267 View Post
    Why doesn't the utility use a copper clad steel instead of all copper for the ground? It would work as well, cost less and be unattractive to the copper thieves.
    Copper-clad steel probably would be cheaper, but the thieves are too stupid to know the difference and will steal it anyway. The materials cost is insignificant compared to the labor cost of repair; it's easier for the utility to minimize the different types of wire they keep in stock.
    The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.

  4. #14
    Join Date
    Aug 2011
    Location
    Northern Indiana
    Posts
    70

    Default Re: neutral grounding @ pole??

    [ The main bonding jumper at the service disconnect assures that any ground faults on a branch circuit will have a sufficient current level to trip the associated breaker. Just my humble opinion.[/QUOTE]

    Exactly, through the bonded neutral in the panel back to the transformer, not through ground rods, water pipes or anything else.

  5. #15
    Join Date
    Nov 2011
    Posts
    9

    Default Re: neutral grounding @ pole??

    Why doesn't the utility use a copper clad steel instead of all copper for the ground? It would work as well, cost less and be unattractive to the copper thieves.[/QUOTE]

    Ground wires are usually covered with a protector, made of wood or PVC. That means the wires are not visible, but thieves still go to the work of prying off the ground guard and cutting the wire. Can't be worth more than a few cents. The bigger problem is substation theft. We see safety meetings every few weeks with graphic pictures of "former" copper thieves (or at least, what's left of 'em).

    Didn't mean to hijack the thread, though. Remember, the utility is there to supply power safely and reliably. Most utilities will not inspect for code violations beyond the utility section of the service panel or switchboard. It's not only that we won't, but we usually don't have the expertise (we are exempt from most NEC regulations). We also set ourselves up for liability issues if we suggest corrections and something bad happens after the fact. That's what building inspectors are for.

  6. #16
    Join Date
    Jan 2011
    Location
    Columbiana, Alabama
    Posts
    720

    Default Re: neutral grounding @ pole??

    Quote Originally Posted by brrichter View Post
    [ The main bonding jumper at the service disconnect assures that any ground faults on a branch circuit will have a sufficient current level to trip the associated breaker. Just my humble opinion.
    Exactly, through the bonded neutral in the panel back to the transformer, not through ground rods, water pipes or anything else.[/QUOTE]

    I agree providing a low Z path through the MBJ to trip a branch ckt. bkr. is the most common scenario.

    But, are you saying ground rods (or any other grounding electrodes) are of no use, except to provide a path to ground for lightning?

    If so and you're correct this country could save a ton of money by just doing away with grounding electrodes and GEC's. All we would need is a few air terminals a triad and not connect to the facility grounding/bonding system.

    So, what part(s) of Art 250 could we eliminate?

  7. #17
    Join Date
    Aug 2011
    Location
    Northern Indiana
    Posts
    70

    Default Re: neutral grounding @ pole??

    Quote Originally Posted by The Semi-Retired Electric View Post

    Exactly, through the bonded neutral in the panel back to the transformer, not through ground rods, water pipes or anything else.
    I agree providing a low Z path through the MBJ to trip a branch ckt. bkr. is the most common scenario.

    But, are you saying ground rods (or any other grounding electrodes) are of no use, except to provide a path to ground for lightning?

    If so and you're correct this country could save a ton of money by just doing away with grounding electrodes and GEC's. All we would need is a few air terminals a triad and not connect to the facility grounding/bonding system.

    So, what part(s) of Art 250 could we eliminate?[/QUOTE]


    I am saying no such thing. What I am saying is that, under normal operating circumstances, the grounding electrode system of a properly installed 120/240 volt system carries no current. The GEC should only see current upon fault conditions, lightning, or an open neutral.

  8. #18
    Join Date
    Jan 2011
    Location
    Columbiana, Alabama
    Posts
    720

    Default Re: neutral grounding @ pole??

    Quote Originally Posted by brrichter View Post
    I agree providing a low Z path through the MBJ to trip a branch ckt. bkr. is the most common scenario.

    But, are you saying ground rods (or any other grounding electrodes) are of no use, except to provide a path to ground for lightning?

    If so and you're correct this country could save a ton of money by just doing away with grounding electrodes and GEC's. All we would need is a few air terminals a triad and not connect to the facility grounding/bonding system.

    So, what part(s) of Art 250 could we eliminate?

    I am saying no such thing. What I am saying is that, under normal operating circumstances, the grounding electrode system of a properly installed 120/240 volt system carries no current. The GEC should only see current upon fault conditions, lightning, or an open neutral.[/QUOTE]

    (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.

    So this statement which has been in every Codebook I can lay my hands on(1996 and later)is wrong? Or is normal operation a fault condition not a design condition? Try lifting the GEC from a ground rod(s))with bare feet
    Last edited by The Semi-Retired Electric; 01-07-2012 at 09:36 PM. Reason: wrong term used

  9. #19
    Join Date
    Aug 2011
    Location
    Northern Indiana
    Posts
    70

    Default Re: neutral grounding @ pole??

    Quote Originally Posted by The Semi-Retired Electric View Post
    I am saying no such thing. What I am saying is that, under normal operating circumstances, the grounding electrode system of a properly installed 120/240 volt system carries no current. The GEC should only see current upon fault conditions, lightning, or an open neutral.
    Try lifting the GEC from a ground rod(s))with bare feet[/I][/QUOTE]

    I've never had any problems disconecting GECs on energized solid neutral systems. A transient voltage or current on a GEC is an anomaly it is not a normal occurence. If there is current on a GEC there is a problem.
    Last edited by brrichter; 01-07-2012 at 09:50 PM.

  10. #20
    Join Date
    Jan 2011
    Location
    Columbiana, Alabama
    Posts
    720

    Default Re: neutral grounding @ pole??

    What I am saying is that, under normal operating circumstances, the grounding electrode system of a properly installed 120/240 volt system carries no current. The GEC should only see current upon fault conditions, lightning, or an open neutral.[/QUOTE]

    BRricher, because of unavoidable voltage drop on the neutral conductor due to un-balanced current being returned to the POCO under normal conditions, that is not true.

    If you have never had a problem with a GEC conducting current or lifting it from the grounding electrodes you have either been extremely lucky or taken measures to prevent it.

    To make that statement to an audience of DIY's or persons who are un-trained in electrical matters but may need to lift a GEC from time to time to perform a task like remove siding etc. with power on is, IMO, not very helpful.

    I started in the electrical business in 1958 ,have been responsible for design, installation and start-up on many $500M projects and have never had a problem either but I've read, studied, practiced and taught everything I can about circulating currents, NEV, loss of neutral, lightning, surges, stray voltage, step voltage, grounding & bonding and power distribution.

    I've always said grounding electrodes are a vital necessity to a complete grounding system, just as bonding, MBJ's and four wire service drops and laterals, and hate to see their role diminished.

    Good Luck from Columbiana, Alabama
    Maurice Turgeon, http://thesemi-retiredelectrician.com

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