what wire to use

Discussion in 'Electrical Forum discussion & Blog' started by killerloop, Mar 30, 2009.

  1. killerloop

    killerloop New Member

    I need to d-bore in power to my shop. it's 450' from panel at shop to transformer. I'm going 200 amp service, I've ben told 250/350 mcm or 4 ot, I want to go underground ALuminum,, I'll go broke using copper.. or is there something else I should use...

    I'll be running 16 high bay lights, welder and air compressor, ceiling fans and garage door openers,,,, think thats it!!!!
  2. Speedy Petey

    Speedy Petey Licensed Electrical Contractor

    NY State, USA
    This is typically a power company issue. I would get with them first and see what they recommend. 450' is a long way to go with secondary (120/240v).

    4/0AL is standard for a 200A service (+/-250' or less), so forget that. You will definitely need 250mcm or bigger.
  3. killerloop

    killerloop New Member

    I ahve asked the power company, and they or KNOW ONE for that matter will give me a straight answer. Seems as if they don't want to stick their neck out, if they are wrong or something, I drill in a lot of power and know quit a few electicians, and really only one guy would say go 350mcm if you can find it. seems ppl don't use mcm much around here
  4. jwelectric

    jwelectric Electrical Contractor/Instructor

    North Carolina
    MCM and KCMIL is the same thing

    For a 200 amp service on other than a dwelling is sized at 250KCMIL or MCM if you prefer to call it that

    For a distance of 450 feet it would be a good idea to upsize the conductors a couple of sizes if the service will come close to seeing a maximum load. If it will not see a maximum load then leaving it at 250 KCMIL would be perfectly fine.

    I have seen services that were a lot longer than 450 feet without upsizing the conductors that never had a problem.
  5. hj

    hj Moderator & Master Plumber Staff Member

    Cave Creek, Arizona

    The utilities, and everyone else for that matter, does not want to tell you a specific size and then have you come back later and try to sue them because you are having power issues. The only way to avoid the issue would be to recommend a vastly oversized wire size, and then you might have other issues with them. The easiest way, and what most supply houses do here, is to NOT give any recommendations and let the actual installer deal with it, and any subsequent issues.
  6. killerloop

    killerloop New Member

    Thats my issue to a T....But I need to purchase wire drill in and pull back before MVE will hook to transformer. And I have yet to pick a electrician... Prob need to get a electrician picked out and have him choose the wire. I just wanted to get this drilled in before I get busy and will never get around to do my own stuff, and it will be winter again!!! Damn snow!
  7. sixlashes

    sixlashes Plumber in Previous Life

    Pensacola. FL
    I just had an underground electrical service installed in my home I am building. The power company strongly discouraged me from running secondary voltage (singles phase 240V) longer than 100 feet underground from the transformer.

    They recommended running primary voltage underground to a transformer on a pad close to the service entrance. Then the underground wire size is a moot point. Two drawbacks - you have to grant an easement to the power company for the land the high voltage runs under and the cost of the transformer.

    My issue was with my home and not a shop. It was worth it to me to spend the couple grand to do it bulletproof. The neighbor across the street did not and the lights in his house flicker whenever his heat pump starts up. It drives his wife crazy.
  8. drick

    drick In the Trades

    I have a 420 foot run from the transformer to the panel and another 70 feet to the heat pump. All wiring was increased one size. I do get some light dimming when the heat pump starts, not bad, maybe 3-4 volt drop, but mildly annoying. It settles out around 118v (down from 120v) under a heavy load. Here the electric co said they did not recommend going over 400 feet on the secondaries, but I balked at the price of the transformer and the fact it was only another 20 feet. In hindsight I think the transformer would have been worth it.

  9. killerloop

    killerloop New Member

    I live on 12.5 acres and the transformer is 40' from my home. But my shop is 435' run.. thinking on 350mcm
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