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    btucker's Avatar
    btucker Posts: 32, Reputation: 1
    Junior Member
     
    #1

    Mar 24, 2007, 07:18 PM
    Equipment ground
    I am wiring a garage from my panel in my home. It is 235 ft from the house. I am wondering If I need an equipment ground and just what the heck is it and how to hook it up and use it? I have a 100 amp load subpanel.
    nmwirez's Avatar
    nmwirez Posts: 453, Reputation: 20
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    #2

    Mar 26, 2007, 04:03 PM
    Good thing you asked. The cabling must be a four wire cable from the main panel disconnect to the subpanel.
    1. The equipment ground conductor (EGC) is the bare wire in that 253 ft. cable to the sub panel. Make sure there is a separate ground terminal bar that is electrically bonded to the metal enclosure that the EGC is connected.
    2. The white neutral conductor is connected to the terminal bar that is isolated from the enclosure. Check to make sure no continuity exists between them.
    3. the other two are hot legs connecting the 120V to each respective breaker bus making a 240V load center.
    4. A main lug only subpanel is not recommended. Safety first. (six breaker handles+ require a main disconnect.)
    5. Be aware of the cable distance for line loss. Compensate with next size up for heavy loading.
    6. Direct burial requires 3" sand bed and 3" top for cable protection from backfill. (USE)
    btucker's Avatar
    btucker Posts: 32, Reputation: 1
    Junior Member
     
    #3

    Mar 26, 2007, 07:28 PM
    Thanks for the help. Now, how do I hook up breakers. I am installing some GFI type and regular breakers for the lights. I also am hooking up some 2 post breakers for a well pump and a welder.
    nmwirez's Avatar
    nmwirez Posts: 453, Reputation: 20
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    #4

    Mar 26, 2007, 08:55 PM
    Quote Originally Posted by btucker
    Thanks for the help. Now, how do I hook up breakers. I am installing some GFI type and regular breakers for the lights. I also am hooking up some 2 post breakers for a well pump and a welder.
    1.one hp well pump 200'... 240V, 20 Amp Dbl Pole... Needs Disconnect at well
    2.Welder... 240V, 30 Amp Dbl Pole... Doesn't if within sight of panel
    3. Lighting... 120V, 15 Amp Single Pole
    4. GFCI circuit... 120V, 20 Amp Single Pole

    Include neutral w/gnd for each circuit.


    All above based on agriculture hookup system for rural home in general. Nm
    tkrussell's Avatar
    tkrussell Posts: 9,659, Reputation: 725
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    #5

    Mar 27, 2007, 02:56 AM
    One important aspect nmwierz neglected to mention is that this garage panel will need an 8 foot ground rod driven, and using #6 copper wire, aluminum not allowed for this wire, connected to the equipment grounding bar in the panel, as per NEC 2005 Section 250.32, Two or More Buildings Supplied from a Common Service.

    This can be reviewed at: http://www.nfpa.org/aboutthecodes/Ab....asp?DocNum=70

    This panel is not a main service, so a main breaker in the panel is not required, may have one if desired, but not necessary.

    As far as voltage drop, assuming no more than a 50 amp load, #2 aluminum will suffice. If the load is more than 50 amps, including the starting amps of motors 5 HP or larger, or a larger welder than 40 amp draw, the next larger wire,#1 aluminum, will be needed.

    You may consider just installing #4/0 Aluminum 4 wire URD cable, to be ready for a future 150 or 200 amp panel.

    Also, any cable or conduit buried must have a warning tape laid 12 inches below grade.

    Depending on the soil conditions, rocky, etc,you may want to consider installing 3 or 4 inch DB conduit for extra protection, and easy replacement of the cable in the future in the event of a cable fault or upgrade, this is a thinwall PVC conduit, reasonably priced, and will not need to be connected at both ends, just let the cable exit the conduit into earth at both ends a few feet away from each building.
    nmwirez's Avatar
    nmwirez Posts: 453, Reputation: 20
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    #6

    Mar 27, 2007, 08:01 AM
    Quote Originally Posted by tkrussell
    One important aspect nmwierz neglected to mention is that this garage panel will need an 8 foot ground rod driven, and using #6 copper wire, aluminum not allowed for this wire, connected to the equipment grounding bar in the panel, as per NEC 2005 Section 250.32, Two or More Buildings Supplied from a Common Service.True in commercial applications where metal piping connects both structures, is not most likely in residential unless metal water pipe is used to garage. 2005 NEC 250.32(B)(2)(1) "where an EGC is not run with supply" and (2)"no continuous metallic paths bonded to a grounding system in each building structure involved."
    Check the price of 235' of copper vs. pvc if you plan to run the well supply by the garage. Usually the well line to house runs 1150psi 1" PVC. 2005 NEC Section 250.32(A) Exception: "A grounding electrode shall not be required where only a single BC supplies the bulding or structure....Multiwire feeder is considered single BC." Unless this is in town and the AHJ doesn't do farms, this is compliant.

    This can be reviewed at: NFPA 70: National Electrical Code® For the average observer this will lead to nowhere. NFPA listings only.

    This panel is not a main service, so a main breaker in the panel is not required, may have one if desired, but not necessary. As mentioned earlier, I do not recommend an MLO, reason, You won't want to walk 235' in the snow to reset the 200A main. Let the 100Amp sub main trip if there is a major event at the garage. (I.e. Well turns on while welding..the surge can trip the sub depending on the total demand. Been there done that.):)
    As far as voltage drop, assuming no more than a 50 amp load, #2 aluminum will suffice. If the load is more than 50 amps, including the starting amps of motors 5 HP or larger, or a larger welder than 40 amp draw, the next larger wire,#1 aluminum, will be needed.
    Go #1
    You may consider just installing #4/0 Aluminum 4 wire URD cable, to be ready for a future 150 or 200 amp panel. Do not waste the $$$.
    Also, any cable or conduit buried must have a warning tape laid 12 inches below grade. Only required on service lateral.[300.5(D)(3)
    Depending on the soil conditions, rocky, etc,you may want to consider installing 3 or 4 inch DB conduit for extra protection, and easy replacement of the cable in the future in the event of a cable fault or upgrade, this is a thinwall PVC conduit, reasonably priced, and will not need to be connected at both ends, just let the cable exit the conduit into earth at both ends a few feet away from each building. Forget the 235' conduit, go 24" deep, the backhoe guy isn't gonna charge you much more over the 18" minimum.
    Save the bucks. Nm ps. Was this helpful for a rating?
    tkrussell's Avatar
    tkrussell Posts: 9,659, Reputation: 725
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    #7

    Mar 27, 2007, 06:04 PM
    Nmwirez, sorry, but you are advising with incorrect information, and misquoting NEC 2005 Article 250, and I believe misunderstanding this Section.

    And you seem to disagree with either my facts or offers of opinions/advice or just for the purpose of contradicting my advice.

    A ground rod is required for this panelboard, period.

    The poster clearly states:
    some GFI type and regular breakers for the lights. I also am hooking up some 2 post breakers for a well pump and a welder.

    To start, Section 250.32 states " the grounding electrode(s) required in Part 3 shall be connected in the manner specified in Sec 250.32(B) or (C)", with the only exception being if only one branch circuit or a multiwire branch circuit supplies the separate building. It continues onto to state "Where there are no existing grounding electrodes, the grounding electrode(s) required in Part 3 of this article shall be installed." then the exception is stated, and determined not to apply in this situation.

    You have misquoted Section 250.32:
    2005 NEC Section 250.32(A) Exception: "A grounding electrode shall not be required where only a single BC supplies the bulding or structure....Multiwire feeder is considered single BC."

    The key word you misquoted is "feeder". The exception for 250.32(A) states "multiwire branch circuit"

    A 100 amp feeder intended to supply a panelboard, that the panel itself is intended to supply several branch circuits, is not a multiwire branch circuit. You even list all the several branch circuits.

    No where does Article 250 mention a difference between commercial or residential grounding.

    You quoted:
    2005 NEC 250.32(B)(2)(1) "where an EGC is not run with supply" and (2)"no continuous metallic paths bonded to a grounding system in each building structure involved."


    First, the word and does not exist in the actual text of NEC 2005 250.32(B)(2), which is for the Grounded Conductor, the (1) text is related to (2) text you refer to is qualified by the word OR, as stated by, quoting this Section exactly:

    250.32(B) Grounded Systems
    "For a grounded system at the separate building or structure, the connection to the grounding electrode and grounding or bonding of equipment, structures, or frames required to be grounded or bonded shall comply with either 250.32(B) (1) or (2).

    The requirement of a grounding electrode conductor has been established by 250.32 (A), and the exception does not apply.

    250.32 (B) then explains if and when the required grounding electrode conductor is allowed to be connected to the grounded conductor, the key word is OR, 250.32(B) does not have anything to do with requiring the ground rod, only if it should be connected to the neutral (grounded) conductor.

    The link to the NEC I provided ,NFPA 70: National Electrical Code®, leads to the actual text of the NEC 2005, not to the NFPA listings only. I explain exactly how to navigate to this in my Sticky "Read This First",I will offer it again;

    Click on link:NFPA 70: National Electrical Code®,

    Then click on "Preview this document" near the bottom of the page,

    Next page click on "I Agree", next page click on "Open National Electric Code".

    You are then presented with the entire actual code, just as if you had the actual book in front of you.

    The Main Breaker issue, I stated,factually, that a MCB s not required, but "may have one if desired".

    You first stated "not recommended" then qualified it erroneously with the statement "(six breaker handles+ require a main disconnect.)". So which is it, not recommended or required?

    "Not recommended" is a valid statement whether opinion or advice, to add "require" is incorrect and confusing.

    You mention the voltage drop issue that can occur with a 100 amp feeder at 235 feet, but offer nothing else than "Compensate with next size up for heavy loading." Next size up from what size?

    I offered an actual wire type and size based on actual load.

    And then you firmly advice "Go #1" one of my answers, without knowing the actual load of welder or motors.

    I offered advice to consider using a much more typical and available larger size wire, that will eliminate any issue with voltage drop, and also offers the poster to think about the future.

    You say save the dollars, which is a valid reason to not install a larger wire, but I gave the poster something to consider, let him decide, he may be sorry later installing a wire too small for voltage drop or future expansion, which the code does recommend, see Section 90.(B).

    Warning tape, OK you got me, is only required for service lateral, as per the NEC. Here in New England, we are required to tape any and all UG conductors, as you like to say "For Safety'e Sake".

    This is why I consistently insist to check with local codes. But to stay with the Safety First suggestion, warning tape only costs $25 for a 1000 foot roll. Repairing a dug up feeder cable sometime in the future can cost much more.

    Last, the DB Conduit suggestion, having a UG feeder at 235 feet, the poster may appreciate the advice of installing cheap UG duct, that again will offer more protection or easy replacement of the cable in the future, for an initial investment of $500.00.


    Contradicting my valid advice or opinion is one thing, I will continue to offer extra suggestions to someone asking for advice, if you insist on discounting my suggestions, have at it, I can handle the criticism or difference in opinion, and I will not offer any other commentary on such in the future.

    However, when it comes to the Code, someone that pretends to be an expert by either misquoting, inserting words that do not exist, or implying something that is incorrect by either misunderstanding or otherwise conveying something not factual, I hope you can handle the criticism, because I will point out any faults in facts.

    Even thou I can or maybe should delete any misinformation I find stated, I will leave other's words as they stand and counter with the facts.


    As for ratings, you may have mine as they are unimportant to me, only providing, safe, accurate, and factual information for those asking question is enough.
    nmwirez's Avatar
    nmwirez Posts: 453, Reputation: 20
    Full Member
     
    #8

    Mar 28, 2007, 01:18 AM
    Thank you for the lengthy and thoughtful response. The present dialog does little in helping at this point. Nm

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