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Thread: Powering Mini Tree Question and GFI

  1. #11
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    Default Re: Powering Mini Tree Question and GFI

    With all the talk of GFCI problems and mini trees, why don't more people use something other than metal for the framing? Is that the cause of the problem(s) or is really an unknown?

    How about something like pvc or fiberglass rods of some sort?

    Just wondering after thinking about this some more.

    Again, I still consider myself a newb so forgive any stupidity in what I say. :D
    As always, Thanks for any info!

  2. #12
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    Default Re: Powering Mini Tree Question and GFI

    Quote Originally Posted by Superfreak3 View Post
    With all the talk of GFCI problems and mini trees, why don't more people use something other than metal for the framing? Is that the cause of the problem(s) or is really an unknown?

    How about something like pvc or fiberglass rods of some sort?

    Just wondering after thinking about this some more.

    Again, I still consider myself a newb so forgive any stupidity in what I say. :D
    Ease of build and accessibility to the materials. Cost. No one has designed a better way yet.

    We know what the problem is, many of us experience it year after year and have reported the same conditions. It is a cumulative effect of electricity leaking from the light strings to the frame and to the ground when everything is wet. I should say we know under what conditions this occurs but I do not know, definitively, what the technical explanation is. Maybe it is not just a simply voltage leak but some type of induction from the way the strings are coiled. When things are dry there is no issue. If we isolate the frames from the ground we solve the nuisance tripping of the GFCI. This prevents the trip but does not solve the issue because the condition still exists, we only prevent the leak to ground. Some have coating their frames for this year. If the condition is a voltage leak I think a non-conductive frame would be the solution but if it is not that simple of an explanation I am not sure what the fix would be. Maybe placing the strings on the frames a different way, up and down vs around and around. I guess we need an engineer to really look at this issue and see if they can resolve this by some better testing methods than I have done. I figured out how to stop the nuisance tripping by isolating the frame from the ground but not how to completely resolve the condition that raises its ugly head when everything is wet. Nothing when it is dry and nothing when there is snow or ice, only when things are wet during and after a rain storm. I have heard of some going out after a rain storm and utilizing a leaf blower to dry off the wet frames to get things working again.
    Thanks,
    Brian, your friendly site Admin.

  3. #13
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    Default Re: Powering Mini Tree Question and GFI

    The coil of the lights during damp conditions makes sense. You have basically created a large inductive coil using the metal frame as a base. I am no expert but I would think stringing the lights vertically would work if this is the case.

  4. #14
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    Default Re: Powering Mini Tree Question and GFI

    Forget about induction. It takes a lot more windings to get any current induced into the metal. It’s actually a current leak since that’s what a GFCI measures, but obviously, voltage has to be there too.

    I have never had a problem with this and I should if it existed since I use lawn staples pounded into the ground to hold my cages down. My GFCI does work though; it was tested in another way.

    Has anybody with this problem ever checked whether they can measure a resistance from either power plug blade to the tomato gage? I’ve always figured that it was from the tiewraps being too tight. If I’m not mistaken, the wire insulation is PVC and with any polymer, there is a certain amount of cold flow. Over time, an over tightened tiewrap will displace the insulation and press the wire up against the metal. It only takes a resistance of 21K to draw 8mA at the 170 volt peak.

    To get an idea what kind of pressure you can get from a tiewrap, cinch one around a finger. Remember you’re only holding the wire there, not trying too survive the wind from a nuclear blast.
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  5. #15
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    Default Re: Powering Mini Tree Question and GFI

    Interesting theory Ernie. Would this condition only exist during wet conditions? If so I will have to wait until I can grab 7 or so mini trees and hose them down to try and duplicate the fault. Then I would have to take a measurement from the cord supplying the 7 trees. Remember this is a cumulative effect, no single tree trips the GFCI, it takes about 7 or so together.
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  6. #16
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    Default Re: Powering Mini Tree Question and GFI

    Hosing several mini trees down may work and it may not. It would depend first on the conductivity of the water. Can you measure the resistance of just a cup of water? If not, then there’s no point in going further. Got a rain barrel? Depending on where you live, rain water can be fairly conductive. You could use salt water, but I think you’d only find out how good your trees would have been and it would be all down hill from there.

    Tony Furst, over on PC, uses a megger. It’s kind of like an ohm meter, except that it applies 1000 volts or more at very low current and looks for a voltage drop. It’s measuring up around a gigaohm.
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  7. #17
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    Default Re: Powering Mini Tree Question and GFI

    WOW. With all that stuff said, what if I create a frame of some sort out of PVC or non-metalic conduit and affix some type of non-metalic string hangers on it so when wrapped the strings don't slide all over the place? Would that work?

    Would that remedy a potential problem of having a 'live'/charged frame and eliminate the need for GFCI? I'm guessing not if wet.

    I haven't been using GFCI with my years of static display where the minis are on bushes.

    I also saw mention of the number of trees with regard to tripping the circuit. I guess I should mention that I am only planning on using two mini trees. I'm a small timer!

    Back to GFCI... im trying to find a GFCI adapter similar to that linked earlier in this thread, but HD didn't have any. I guess I'll try Lowes.

    Thanks in advance for any more info!
    As always, Thanks for any info!

  8. #18
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    Default Re: Powering Mini Tree Question and GFI

    I went ahead and bought some 1 1/2" conduit to whip up some 3' mini tree frames. I also modified some plastic mini light clips that will be affixed with epoxy and will run the length of the 3 uprights.

    I'm hoping the mini strings will sit on these clips nicely and will not slide up/down the frame.

    I just have to figure out how to best connect the three uprights. I'm either going to epoxy them on the top or capped end or use a cable tie.
    As always, Thanks for any info!

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