New Daisy-Chain Calculator for LED's!

Discussion in 'Landscape Lighting' started by steveparrott, Feb 18, 2011.

  1. steveparrott

    steveparrott LawnSite Bronze Member
    Messages: 1,276

    Fellow Lighting Geeks,

    The new LED revolution finds LL installers reverting back to the daisy chain method of wiring. Since wattages are much lower, it does make sense (in some installations) to tap off along a single wire run instead of using multiple home runs to Spider Splice locations.

    I was curious about this so I made some calculations and was surprised to find that voltage loss is still an important consideration. This is especially evident when the higher-wattage LED fixtures are used, and when you need to combine incandescent fixtures and LED fixtures.

    In some situations, you need to move up to the 13, 14, or 15V taps. In other situations, the voltage loss between the first and last fixture exceeds the voltage range of the particluar LED.

    With this in mind, I created an Excel calculator that predicts voltage loss. (Eventually, I'll convert it into a web page.)

    I strongly encourage anyone who likes playing with calculators, to download this calculator (beta version), put it to the test, and post feedback in this thread.

    All who provide relevent feedback get a free CAST Lighting hat!:)

    Download the new CAST System Calculator - Daisy Chain Version.

  2. RLI Electric

    RLI Electric LawnSite Senior Member
    Messages: 381

    Make it into an app. A free one please:)
  3. NightScenes

    NightScenes LawnSite Silver Member
    Male, from Kingsland, Texas
    Messages: 2,214

    For BB too, please! LOL

    Thanks Steve!!!
  4. steveparrott

    steveparrott LawnSite Bronze Member
    Messages: 1,276

    Paul and Bob, did you try out the calculator? I'm really looking for feedback.

    I also have a meeting tomorrow with my developer about the aps.

  5. NightScenes

    NightScenes LawnSite Silver Member
    Male, from Kingsland, Texas
    Messages: 2,214

    Just now downloaded it so give me a few days Steve. I'll try it out.
  6. JG Supplies

    JG Supplies LawnSite Member
    Messages: 1

  7. steveparrott

    steveparrott LawnSite Bronze Member
    Messages: 1,276

  8. Fireguy97

    Fireguy97 LawnSite Senior Member
    Messages: 394

    Am I missing something? I didn't get an xls file in the compressed file.

    Tried to open with Excel 2003

  9. steveparrott

    steveparrott LawnSite Bronze Member
    Messages: 1,276

    This is a strange quirk with Internet Explorer - it interprets an .xlsx file as a .zip file. It opens fine in Firefox or on a Mac.

    Ed Lethert (The Low Voltage Guy) has taken on the development of this calculator as a work of passion. We've been going back and forth for months with various drafts and Ed has spent countless hours refining the calculations.

    Unlike a calculator for incandescent lighting, LED's with their complex drivers inject variables that are not easily calculated. You'll see in the current version several refinements over the previous draft. These include the ability to use the calculator for the T-Method, temperature compensation, a +20% column for adjusting for errors that come in with very large systems, energy cost calculations, alerts when voltage ranges are exceeded.

    By the way, to calculate a T-Method installation, use junction 1 to indicate where the homerun connects with the middle fixture. At that junction, put all the fixtures from the shorter leg of the T, then continue to enter each fixture junction on the second leg of the T.

    For example if the set-up looks like this:

    F1 F2 F3 F4 F5(T-Junction) F6 F7 F8 F9

    Enter the first 5 fixtures at the first junction; then J2 is fixture 6, J3 is fixture 7, and so on.
  10. irrig8r

    irrig8r LawnSite Platinum Member
    Messages: 4,553

    Opens in Chrome.

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