copper pipes grounded ?

Discussion in 'Electrical Forum discussion & Blog' started by reed50, Jul 22, 2010.

  1. reed50

    reed50 New Member

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    About 5 years ago we had the plastic grey pipes in our manufactured home replaced with copper pipes. The pipe to the house is plastic. It stayed. I ran across something the other day that said the copper pipes need to be grounded. I'm pretty sure this is not something that was done. Is this something that is necessary and can someone explain why? Thanks for your help.
  2. Terry

    Terry Administrator Staff Member

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    If a live wire contacts the bare copper pipe, and it's not grounded, it can kill you if you touch the pipe or a faucet.

    Plumbers have died working on ungrounded copper pipes.

    Correction below by jwelectric

    Last edited: Jul 23, 2010
  3. Fubar411

    Fubar411 New Member

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    My understanding is copper doesn't get grounded, it gets bonded.
  4. Ian Gills

    Ian Gills Senior Robin Hood Guy

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    And my understanding was that plumbers don't die, they just smell that way.
  5. Terry

    Terry Administrator Staff Member

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    And some how that appeals to an Englishman?
  6. Ian Gills

    Ian Gills Senior Robin Hood Guy

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    Just stating a matter of fact.

    Electricians don't die, they just "Watt away".
  7. Terry

    Terry Administrator Staff Member

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    "Watt away"?
    I'm shocked to hear you say that.

    What is it Sparky's?
    Grounded or bonded?

    People want to know these things.

    I know it's not a good idea to work off an aluminum ladder while doing electrical work.
  8. Ian Gills

    Ian Gills Senior Robin Hood Guy

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    Even in the pool?

    And since the pipe to the house is plastic, it's bonding. If it were a metal underground water pipe, it would be both grounding and bonding.

    The way I think about grounding versus bonding when I DIY is as follows.

    The easiest way to understand grounding is that in the electrical system all connections made from the system to planet earth is considered “grounding” and serves the following main purpose.

    High-voltage system windings are grounded to the earth to help limit high voltage imposed on the system windings from lightning, unintentional contact with higher-voltage lines, or line surges.

    Metal parts of electrical equipment must be grounded to the earth by electrically connecting the building or structure disconnecting means with a grounding electrode conductor to a grounding electrode.

    Examples of grounding electrodes are: metal underground water pipe; metal frame of building or structure; concrete encased electrode (ufer); ground ring; rod or pipe electrode; or, a plate electrode.

    The grounding of the electrical system to the earth is for lightning & line surge emergencies and to aid the utility company. It will never help in clearing a breaker or fuse at the actual dwelling.

    Why?

    Typical ground rod might have 20 ohms of resistance. Ok….120V source and 20 ohms of resistance/impedance….120V divided by 20 Ohms =6 amps
    That will not clear a 15 amp breaker.

    So what is bonding?
    To remove dangerous voltage on metal parts from a ground fault, electrically conductive metal water piping systems, metal sprinkler piping, metal gas piping, and other metal piping systems, as well as exposed structural steel members that are likely to become energized, must be bonded to an effective ground-fault current path [250.4(A)(4)].

    It is also important to remember the important role electrical metallic conduit serves as well for bonding….this is not grounding !

    What is important to understand with bonding is that proper bonding of metal piping and conduit within the structure offers a low resistance fault current path back to the source in the event it becomes energized allowing the breaker or fuse to function properly.

    Without this path you can guess what would happen if a clumsy plumber were to touch metal that might become energized….

    So, dummies' summary for plumbers: Grounding is the connection to earth and bonding is the connection of metal parts to provide a low impedance path for fault current to aid in clearing the overcurrent protection device and to remove dangerous current from metal that is likely to become energized.
    Last edited: Jul 22, 2010
  9. hj

    hj Moderator & Master Plumber Staff Member

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    quote: So, dummies' summary for plumbers

    Another one would be that 120 volts divided by 20 WATTS, (NOT ohms), is 6 amps. And even a NONclumsy piumber can be injured by a poorly installed electrical system which is using the plumbing for a neutral to earth. In that case, HE could be the electrical route if he separates the piping. In Chicago, I ALWAYS hit the piping with my wrench after loosening a union, and more than once I was rewarded with a "flash" as the electricity arced across the resulting gap. Once resulting in everything which was turned on at the time burning out.
  10. jwelectric

    jwelectric Electrical Contractor/Instructor

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    Grounded means connected to earth.

    Bonded means connected to the service grounded conductor.

    To bond the metal water pipe would ensure that there is a low resistance path back to the service in order to open the overcurrent device (fuse or breaker). Bonding also ensures that the pipe is connected to earth.

    It is possible to ground (connect to earth) the metal water pipe and the pipe not be bonded. In this case, someone coming in contact with the grounded metal water pipe and something that is energized a path would be established between the person and the grounded conductor in the service equipment and this person would be in series with the circuit thus carrying all the current in the path.

    No, it is not so important to ground the pipe as it is to ensure it is bonded. If the home has a water heater then the pipe is bonded through the equipment grounding conductor in the branch circuit supplying the water heater. If there is anyone who thinks this would not bond the metal water pipes then none of the pipes would require bonding. If the metal water piping system is mixed with nonmetallic fittings or anything else that would break the continuity then no bonding is required and again trying to ground the pipes could prove to be deadly.
  11. Ian Gills

    Ian Gills Senior Robin Hood Guy

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    Codes are silly.

    I jumpered my water meter when I moved in.

    During my last service upgrade the electrician removed this as it was no longer required by Maryland code.

    The inspector agreed.

    And yet they insist on a ground rod.
    Last edited: Jul 24, 2010
  12. jimbo

    jimbo Plumber

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    Well, Mr. Ohm's legal staff would take issue. P = I x E, so if you are given 120 volts and 20 watts, the answer for amps would be 20 divided by 120, not the other way.
  13. jwelectric

    jwelectric Electrical Contractor/Instructor

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    But in most areas they are the law and must be followed. There is a process in which these codes can be changed.

    Most people doing silly things such as this do so through ignorance. A simple course at your local community college would help.

    See how silly your jumper was.

    Now I wonder why they want something like that. I bet it has to do with the definition of grounded as defined by the NEC.
    Ground. The earth.
    Grounded (Grounding). Connected (connecting) to ground or to a conductive body that extends the ground connection.
  14. Ian Gills

    Ian Gills Senior Robin Hood Guy

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    Like a metal underground water pipe which we've already got.

    Surely dry soils compromise ground rods.
  15. jwelectric

    jwelectric Electrical Contractor/Instructor

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    The underground metal water pipe should you have at least 10 feet in contact with earth becomes a grounding electrode and would be required to be connected within the first five feet after entering te building and another electrode must be added with it just in case someone decides to replace the metal water pipe with something else
  16. Terry

    Terry Administrator Staff Member

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    When I first started plumbing we were required to leave 10" of soft copper outside the house for the electricians.
    And then copper went up in price, and people were going around and cutting the copper off before it could be buried and selling it for scrap.

    I haven't installed more then a foot of copper outside a foundation since the 70's.
  17. jwelectric

    jwelectric Electrical Contractor/Instructor

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    In which case there is no grounding electrode and no need of a connection within the first five feet. Should the interior metal be installed in a manner where it was not 100% complete metal then the grounding electrode to the water heater is all that is required.
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