Exisiting electrical to barn and help to rectify

Discussion in 'Electrical Forum discussion & Blog' started by backwaterdogs, Sep 9, 2012.

  1. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,129
    Location:
    New England
    Who owns what depends some on where you live...
  2. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,540
    Location:
    North Carolina
    This is true but no matter who owns it unless the utility installs the equipment then sealing the meter base will not allow anyone other than the utility to effect repairs.
  3. backwaterdogs

    backwaterdogs New Member

    Messages:
    51
    Location:
    Illinois
    ok, so Im planning on putting in a new a new 200a panel with a few spaces on the downstream side of the existing service disconnect.

    I'll run appropriate size copper to this new panel mounted w/in a few feet of the existing pole. I'll have a 100a breaker to service the cabin (there is already 2/0 copper to the cabin from the existing service disconnect, I'll reroute). I'll have an 85a breaker for service to barn and I'll reroute the existing #4.

    My next question is on grounding and bonding.

    In the existing service disconnect, the neutral and ground are connected (though I don't see a bonding screw) and I'm assuming neutral is bonded by the fact the ground/neutral strap are one and the same,:
    barn9.jpg
    So, assuming the 1st service diconnect is bonded, I should ensure this new panel Im putting is unbonded as well as any downstream subpanels, correct?
    If so, I notice another problem w/ existing service in cabin, the subpanel in cabin appears to be bonded as the box doesn't have separate straps for ground and neutrals:
    barn10.jpg

    On to the barn:
    Though there is no other metalic connection to barn whatsoever, I believe I need to pull a ground as well(i'll have 3 #4 and 1 #6 from new panel to barn) to meet 2008 code.
    I should leave subpanel in barn UNBONDED, correct?
    Do I need a ground rod at the barn as well?

    Thanks for all the help!
  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,129
    Location:
    New England
    Neutral and ground are only to be bonded at the first panel...all down-stream ones they should be separate. Each building needs its own grounding rods (min of 2). As to how best to do this, I'll defer to the pros...
  5. ActionDave

    ActionDave Electrician

    Messages:
    351
    Location:
    Colorado
    You need a ground rod at the barn. It will tie to an Equipment Ground Buss that is installed by you. Instructions will come with the panel. Neutrals go where you would expect to see them.
  6. backwaterdogs

    backwaterdogs New Member

    Messages:
    51
    Location:
    Illinois
    Thanks everyone!

    I'm having a heck of a time sourcing the panel with space for 100a and an 85a break to feed the cabin and barn

    Anyone have any suggestions on model or part number? Local electrical supply had nothing in stock and wanted $200 to order!
  7. ActionDave

    ActionDave Electrician

    Messages:
    351
    Location:
    Colorado
    There should be no problem finding a 200A panel and breakers at home desperate. You won't find an 85A breaker, but you will find a 90 and a 100.
  8. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,540
    Location:
    North Carolina
    For #4 Copper conductors nothing bigger than 80 amps
  9. big2bird

    big2bird IBEW Electrician

    Messages:
    141
    Location:
    Anaheim, Ca.
    Two? Please reference a code.
  10. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,129
    Location:
    New England

    Parrotting what (I think) I've heard other's say that should know the codes...
  11. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,540
    Location:
    North Carolina
    Which cycle do you want referenced. It has always been a requirement that at least 25 ohms of resistance or two rods. For 2008 see 250.56 and in the 2011 see 250.53(A)(2)
  12. big2bird

    big2bird IBEW Electrician

    Messages:
    141
    Location:
    Anaheim, Ca.
    Yes, 25 ohms or less is the requirement. There is no automatic requirement for two. When updating a service entrance, most local inspectors will know the soil resistance as measured by a biddle tester, and will instruct you as to their requirement.
    For the most part, sandy/dry soil is the enemy. Beach and desert areas will most often require two.
  13. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,540
    Location:
    North Carolina
    The 2011 cycle states that two rods must be installed unless the electrical contractor hires a Professional Engineer to perform the test.

    The clamp on testers only read the ground loop between the grounding electrode on the premises wiring and the supplying transformer grounding electrode. This is not earth resistance.

    I have been in the electrical field for more than 44 years and have never known an electrical inspector to perform any type of electrical test especially on the grounding system. The resistance of the grounding electrode will vary with weather conditions so a test done today will be different than one done tomorrow.

    As an electrical inspector for NC should I come out and see only one rod at any location then the electrical contractor will have to produce a written report from a Professional Engineer and I will not accept the results of only one test.

    EDITED TO ADD;

    Here is the only test that counts
    http://www.esgroundingsolutions.com...-induced-frequency-ground-resistance-test.php
    Last edited: Sep 30, 2012
  14. big2bird

    big2bird IBEW Electrician

    Messages:
    141
    Location:
    Anaheim, Ca.
    I guess I am behind the times. I bow to your up to the minute knowledge.We are still working off of the 2010 here in most all building departments.

    BTW, by a Biddle earth tester, I mean the meter you use attached to two test probes 6' apart. I generally have to get third party certification on any public works project. Testing between the SE and the utility ground would be irrelevant.

    I just read that link. Basically, it makes it more cost effective to add a second ground electrode than to test. It would be easier to just mandate it, and be done with it.
    Last edited: Sep 30, 2012
  15. backwaterdogs

    backwaterdogs New Member

    Messages:
    51
    Location:
    Illinois
    ok, I got the double lug problem resolved at service disconnect just below meter at pole.

    I found the neutral that was in the barn. Indeed, it was just run a ground rod. I'm in the process of pulling a new conductor for neutral in barn.
    The existing conduit w/ the exising #4 conductors is 1" sched 40 pvc. Smaller than I'd like, but I think I get the 4th conductor in there.

    My problem remains in the barn, I had an existing 100a main breaker panel (square d w/ many breakers), but will be oversized to protect that #4 au. For various reasons, I'd rather not dig up the 200ft of existing #4 and I can't find an 80a main breaker.

    So, can I put in a disconnect w/ 80a breaker to feed the 100a main I already have?
  16. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,540
    Location:
    North Carolina
    Yes, protect the conductors where they originate and if they are #4 then a 50, 60, 70, or 80 amp breaker will work and it doesn’t matter what size breaker that is in the panel at the barn
  17. big2bird

    big2bird IBEW Electrician

    Messages:
    141
    Location:
    Anaheim, Ca.
    I think you will find that quite difficult.
  18. backwaterdogs

    backwaterdogs New Member

    Messages:
    51
    Location:
    Illinois
    you're right, i messed w/ trying to pull that #4 thru the existing 1" for awhile...I couldn't even get a fish tape thru the 100' of conduit.

    So, I have pulled out the exsiting #4 conductors (actually, 1 was bigger, #3 or #2) and lining up a trencher to cut a trench and put down new, bigger conduit. i'm now faced with another decsion:

    1) Put in the 100' of 2"+ conduit and re-pull the existing #4 copper that I have. This will only cost me another 80a breaker and box at pole to protect the #4.

    2) Put in #3 copper (haven't priced al. yet) so I have full 100a capacity should I ever need it. This will cost me 300' of #3 copper conductor at over $125/ft. I could probably sell the $4 I have to defray some of the cost.

    I started this project to get the service in my barn safe at minimal expense, which seems to point to option 1, but I do like the idea of having service appropriately size for 100a, altough I don't see me utilizing it.

    Any thoughts? thanks!
  19. big2bird

    big2bird IBEW Electrician

    Messages:
    141
    Location:
    Anaheim, Ca.
    Yes. I would invest in option #2. You could use one of your existing 4's as a ground.
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