How do you calculate voltage drop???

Discussion in 'Landscape Lighting' started by djt22, Jul 21, 2011.

  1. djt22

    djt22 LawnSite Member
    from Ohio
    Posts: 113

    How do you calculate your voltage drop and do you do different methods depending on what transformer you use?
  2. The Lighting Geek

    The Lighting Geek LawnSite Senior Member
    Posts: 875

    Well, it just so happens I had to brush up on this very thing to pass my CLVLT test last weekend. The formula most people use is: watts x length of wire in feet, divided by the wire constant, X 2 (because it is AC)

    The constants are:
    16/2: 2200
    14/2: 3500
    12/2: 7500

    OK, did I get that right? LOL
    TRUST ME, if I am incorrect someone will correct me. :)
  3. Richie@

    Richie@ LawnSite Member
    Posts: 187

  4. steveparrott

    steveparrott Sponsor
    Posts: 1,199

    Tommy's formula is essentially correct for a single wire run with a single fixture or multiple fixtures connected with a hub or Spider Splice.

    For more complicated calculations, I suggest you use one of these CAST calculators:

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