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Low Voltage Transformer Trouble

Discussion in 'Landscape Lighting' started by jimmy1111, Jan 19, 2009.

  1. JoeyD

    JoeyD LawnSite Silver Member
    Messages: 2,933

    If you cracked the case I know it would void our warranty. But ours are riveted shut. Some manufacturers prefer to just screw theirs closed. If the wires to the core are charred then the core is shot. It may still work but I know we would throw it away. The core itself should never go bad unless it burns up.

    BUt I would concur with Steve....Meltdowns occur 99% of the time due to BAD CONNECTIONS producing Arching!!!
  2. jimmy1111

    jimmy1111 LawnSite Member
    Messages: 56

    Joe Thanks. Mine had one riveted / or spot welded seemed like sodder but soft silver color and one screw that was holding it in place - just odd why they had 2 types in the back. The others on the side top portion seemed to have snapped with the shipping and handling 7 years ago.

    what did you mean by cracked the case. Does that mean break the spot welds / rivets ?

    Also; 2 wires in the previous Picture that are bad were from the core to the breakers. I'm assuming you mean by the core the same as the others refer to it as coil.

    Can i just splice these darn cables and be done with it since my warranty is most likely voided anyways ? Also what gage of wires Unique uses inside your Transformers on the secondary side?
  3. David Gretzmier

    David Gretzmier LawnSite Gold Member
    Messages: 3,645

    wires melt because of overloading, or arc-ing because of a bad connection. if you want to use 10 guage and replace these wires, and really cinch down the connections, go for it. make sure you mount this trans on a nonflammable post far enough from your house so as to not cause a fire to your home.

    "cracking the case" is opening it to the coil. once you open it, the manu has no idea if the problem was caused by them or by the person opening the case, as they have no way of knowing whether the problem was caused before or after the case was opened.

    for me, when I have this kind of a problem with a trans, I replace the trans. and I am mr handyman when it comes to fixing things. I am also mr. "I don't want to burn someone's house down because I THOUGHT I could fix a trans". .

    I also firmly believe that a 12 guage "loop" cannot handle a 270,290 watt load. Your melted wires may have been a problem inside the trans, but you've got other things going on there that make alarm bells go off in my head.
  4. jimmy1111

    jimmy1111 LawnSite Member
    Messages: 56

    Dave thanks for the FXL Reference helpfull but doesn't show loop installation's impact.

    Isn't installing Loop wires like cutting the load in half at the tap ? in other words isn't 270 W circuit with loop installation equates to about 135 W on each leg and 10.4 amps at the 13 V Tap ? again this is just approximate numbers since it is dependant on which side of the loop that has the most load.

    If the answer is a "NO" Than all I have to do is to cut the loop in 2 equal loads ?
  5. SamIV

    SamIV LawnSite Senior Member
    Messages: 324

    Theoredically if you loop correctly with 12 gauge wire, this will bring you up to a 10 gauge wire. So if you are correct in saying you have 290 watts of lamps on this loop not accounting for loss due to the wire itself, you are at 80% of the rating of a 10 gauge wire or 24 amps. This scenario does sound like bad connections.

    You have to realize that you are pushing these runs to their limit and drawing max current.
  6. irrig8r

    irrig8r LawnSite Platinum Member
    Messages: 4,553

  7. JoeyD

    JoeyD LawnSite Silver Member
    Messages: 2,933

    you need to return that unit or buy another. I would not try and put a band aid on a unit that obviously has some issues...this time it was a simple internal failure, next time could be a blackened wall! Just get a fresh unit up on the wall and start clean! That would be my advice! I know if that unit was made by me I would warranty it with no questions asked!!!
  8. JoeyD

    JoeyD LawnSite Silver Member
    Messages: 2,933

    Understand that it is rare that wire will melt down due to overload.......amps create heat, not watts.......it takes quite a bit of amps to melt cable, like Steve said and I agree, majority of all melt downs occur from a faulty or loose connection. Wire your system up and test your amperage loads. You should be running no more than 16amps on your 12ga. No more than 24amps on your 10ga. Simple as that. Your amp meter will tell you everything you need to know. Its not hard to calculate your VD...

    amps (watts/12) X Resistance (12ga=.00162 10ga=.00108) X wire length X 2 (A/C)

    amps X Resistance X Wire Length X 2 = VD
  9. jimmy1111

    jimmy1111 LawnSite Member
    Messages: 56

    I got a Voltmeter wich also measures the Resistance R. R=Volts/Amps...I guess i can get my Amps that way and I'm planning on doing that tomorrow Sat. and will post the numbers.

    Shall I measure the Amps on each fixture? or at the first fixture only, or the last fixture in the run ?..maybe also at the Taps ? which location usually get the highest amp reading ? or the amps usually is the same on a constant run length when loaded?

    Also I found an article that says installing Loop Runs will cut your Run Length in half...is that true ? or as Sam Said looping a 12 AWG is theoratically equivalent to have a 10 AWG wires ?
  10. Chris J

    Chris J LawnSite Silver Member
    Messages: 2,843

    You need to measure your amps at the transformer. Test each individual run right at the terminal blocks. Testing the amps at the fixtures will give you some information, but you need to know the total load being placed on the wire and the trans. If you have several runs coming out of the same circuit, you need to also test all of these at the same time. Place your clamp meter around every wire (at one time) coming out of each common.

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