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  1. #1
    Join Date
    Nov 2004
    Location
    Atlanta, Ga. burbs
    Posts
    281
    I have 2 200 amp panles in the basement of my house. Oversized on purpose some 18 years ago.

    I want to run about 100 to 125 feet of electrical wire to my 2 car garage not attached to the house. In it I have a 100 amp panel. I have no intentions of welding (don't know how) high priced wood working equipment (too cheap) etc. Basically just lites and outlets. I will never have HVAC in it if I use heat it will be either oil or propane.


    The Home Desperate clerk suggested I use BIG aluminum wires and put it under ground (#2) I think. I am scared of aluminum wiring and think cooper is best for me. I also do not trust the Home Desperate (Depot) since the electrical genius may work in the hardware section and may not have a clue.

    Any suggestions and these are just suggestions on the size of wire I would need to put in the conduit to the building? I was always told it is better to over size the wire just in case someone else may want to use the building as a shop.
    I am also planning on not running a ground wire to the main power and drive in a ground rod at the detatched shop. (Three wires hot hot and neutral. Elec. box in detatched garage has the ground isolated from the neutral as well.

  2. #2
    Join Date
    May 2004
    Location
    Illinois
    Posts
    2,843
    I've got almost exactly the same setup at my house.

    (3x) #2 Copper out to the garage, with a 100A panel. #2 is good for 115A.

    I believe that the code allows you to down-size the ground wire for a service like this to maybe a #6 or 8. You can drive an additional ground rod off the garage panel, but I'm pretty sure it has to be tied back into the main service.

    Don't have an NEC handy, but I'm sure you'll have a couple sparkies chime in here any minute.

  3. #3
    Join Date
    Jul 2000
    Location
    Dallas,Texas
    Posts
    4,972
    To be legal you will need to run a ground wire AND drive a ground rod at the garage

  4. #4
    Join Date
    Jan 2005
    Location
    North Las Vegas
    Posts
    784
    Hmmmm this sounds like a DIY project, if that is the case check with your local Building Inspector as he will know what local codes apply in your area. Of course this may require pulling a permit and having it inspected.

    I have yet to figure out why consumers expect sales people at Home Depot and stores of that nature to be experts, for the most part they are nothing more then sales personnel with limited knowledge of what they are selling, they have expectations that the customer knows what they need and will direct them to that area.

    Far better it is to dare mighty things, to win glorious triumphs even though checkered by failure, than to rank with those poor spirits who neither enjoy nor suffer much because they live in the gray twilight that knows neither victory nor defeat. (President Theodore Roosevelt)

  5. #5
    Join Date
    Jan 2004
    Posts
    933
    Q- When is #2 Al no longer good for 115 A?
    the average for me using the sizing formula, seems to be about 75 foot and I must derate, and go bigger. find a table for conductor sizing or the formula. the ampacity goes down with the greater length. Al is a fine service conductor.
    Still learning opinions welcome.

  6. #6
    Join Date
    Nov 2001
    Location
    Seattle, WA
    Posts
    7,774
    Originally posted by retired btc
    I have yet to figure out why consumers expect sales people at Home Depot and stores of that nature to be experts, for the most part they are nothing more then sales personnel with limited knowledge of what they are selling, they have expectations that the customer knows what they need and will direct them to that area.
    Because most of the advertising I see around here anyway says things like if you want to know the most about ...pick a subject =paint, wiring, lights, etc, etc, see our people at Home Depot or to that effect.
    "The American Republic will endure until the day Congress discovers it can bribe the public with the public's own money.
    - Alexis de Toqueville, 1835

  7. #7
    Join Date
    Jan 2005
    Location
    North Las Vegas
    Posts
    784
    By this statement alone he knew better then to ask lol


    (The Home Desperate clerk suggested I use BIG aluminum wires and put it under ground (#2) I think. I am scared of aluminum wiring and think cooper is best for me. I also do not trust the Home Desperate (Depot) since the electrical genius may work in the hardware section and may not have a clue.)

    But rather then check with a licensed Professionial its easier to slam the poor guy working for 10 bucks an hour in a retail store. The term Expert as applied in those stores should be taken with a grain of salt and understanding that they are not Licensed Professional's in the Trades and most likely have no Trade School backround.



    Far better it is to dare mighty things, to win glorious triumphs even though checkered by failure, than to rank with those poor spirits who neither enjoy nor suffer much because they live in the gray twilight that knows neither victory nor defeat. (President Theodore Roosevelt)

  8. #8
    Join Date
    Jan 2004
    Posts
    933
    Not all "home boys" are clueless, ask the guy with the dirty apron he may know, the clean aprons are the ones you have to watch. I deal with the first shift people monday through friday and they are pretty good.
    Still learning opinions welcome.

  9. #9
    Lemme get this straight... people are supposed to trust the goons at Home Depot instead of consulting a licensed professional? When it comes to electricity in the home they live it? Where their kids sleep? Spend a few dollars and have an electrician spec the job and pull a permit if you want to do the grunt work...

  10. #10
    on a similar note I heard an electrician telling a guy the other day that if you have direct burial cable it needs to be bigger than cable in the air for the same load he said the ground does not allow it to shed heat as fast as the air, at first I though no way but now I'm not so sure lol any electricians out there have an answer to this?

  11. #11
    Join Date
    Nov 2002
    Location
    emerald city, sc
    Posts
    1,469
    Originally posted by btj steamfitter / ref
    on a similar note I heard an electrician telling a guy the other day that if you have direct burial cable it needs to be bigger than cable in the air for the same load he said the ground does not allow it to shed heat as fast as the air, at first I though no way but now I'm not so sure lol any electricians out there have an answer to this?
    so if i run geothermal pipes above ground, my system will work better than buried pipes. why am i digging ditches?
    i wanted to put a picture here

  12. #12
    Join Date
    May 2004
    Location
    Illinois
    Posts
    2,843
    Originally posted by control_noob
    Lemme get this straight... people are supposed to trust the goons at Home Depot instead of consulting a licensed professional? When it comes to electricity in the home they live it? Where their kids sleep? Spend a few dollars and have an electrician spec the job and pull a permit if you want to do the grunt work...
    Tell me why you can buy a gas water heater, but not a gas furnace..

  13. #13
    Join Date
    Jul 2000
    Location
    Dallas,Texas
    Posts
    4,972
    Originally posted by control_noob
    Lemme get this straight... people are supposed to trust the goons at Home Depot instead of consulting a licensed professional? When it comes to electricity in the home they live it? Where their kids sleep? Spend a few dollars and have an electrician spec the job and pull a permit if you want to do the grunt work...
    Weren't you just asking about a sub panel to a tankless water heater, in another thread?

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