Help me understand this.

Discussion in 'Landscape Lighting' started by starry night, Jun 17, 2014.

  1. starry night

    starry night LawnSite Gold Member
    Messages: 3,321

    I had a phone call today from a man who said he had LED lights installed last November by a landscaper guy he knew and recently the the LEDs started flashing when they were on.

    I usually qualify callers, but in this case, by coincidence I had an appointment near him this afternoon so I arranged a time to take a look.

    Very nice home but I notice big box store integrated LED fixtures and a Hampton Bay transformer (Home Depot). I started at the beginning.... 118 volts coming out of the house. Turned on the transformer. Yep, LEDs are flashing (brightly). Touched my leads to the transformer lugs. Reading on my Fluke meter is 0.00.
    Went to one of the Quick Discs that were used for connections. Unscrewed the cap and touched the contacts. Reading is 0.00 while LEDs are still flashing.

    My conclusion is that the transformer is defective. But I don't understand how the LEDs worked in any way with a reading of 0.00 from the transformer.

    Obviously, I am not going to work on this amateur system but I am still curious about what I found. What's the answer?
  2. steveparrott

    steveparrott LawnSite Bronze Member
    Messages: 1,276

    Discounting problems with your meter or its settings, or the unlikely possibility that the transformer is putting out DC instead of AC; then I wonder if the installer wired the LED fixtures in series instead of in parallel.

    In other words the wire from the voltage tap goes in one side of the fixture and out the other side to the next fixture. Taking a reading across the quick connect would then give you a zero reading since you would only be testing one leg of the circuit. At some point in the system, the current would need to get back to the transformer, so maybe the one wire loops back from the last fixture.
  3. starry night

    starry night LawnSite Gold Member
    Messages: 3,321

    Fluke meter is only weeks old and I have been using it regularly.

    (My error in the original post. It is a less expensive Fluke and only reads to the tenths.)

    But how does one explain the 0.0 volt reading across the common and 12 v tap with the LEDs flashing?
  4. S&MLL

    S&MLL LawnSite Senior Member
    Messages: 751

    Step#1 Move your meter to dc and see what it reads.
    Step#2 Throw out that junk and install a professional grade system. We charge 85 dollars a hour for service work. That means once I get out of the truck they normally owe me more for my service call than they paid for their entire system.
  5. starry night

    starry night LawnSite Gold Member
    Messages: 3,321

    Thanks Matt and Steve, Unfortunately, I could tell right away that this client wasn't going to opt for a new system. I suggested that none of the components were professional grade, but to start with, a quality transformer would cost him $***. And that is as far as I could go. He said his wife would never let him spend that kind of money on landscape lighting. (BTW Matt, I know you like to jab me (no harm taken) but sales and business promotion is my strength. I have learned a good amount from research on the technical side but this one had me puzzled.

    So this thread is merely for my education, if you guys don't mind.
    Because of my inexperience, it didn't occur to me to check DC voltage.
    Are there DC low voltage transformers on the consumer market?

    From what the customer told me on the phone, I thought it might be under-volted LED flickering but this turned out to be flashing at full-light.

    Supposing it was a DC transformer, what might cause the LEDs to flash after 7 months? Bear in mind that these were inexpensive integrated LEDs from Home Depot.
  6. RLI Electric

    RLI Electric LawnSite Senior Member
    Messages: 381

    Not sure if this could be an issue but if the transformer is bad, there still may be enough power "trickling" through that could be enough to fire up the LED's for a second. I see this with older Lutron Radio RA switches and LED's on the interior quite often. Even though the switch is "off" there is still a trickle making it through as the switch is a "smart" switch and needs that trickle charge. Because of that, the load, if it is LED, never shuts off it just goes down to 5%.
  7. LLC RI

    LLC RI LawnSite Member
    Messages: 149

    Phil, This is an interesting conundrum. I'll toss my hat into the ring on this. 1. Could be a bad fixture is 'poisioning' the rest of the lights, making them flicker. I had a bad driver on a RAB path light that I had them make for me to run on 24 vdc- had the same thing happen.
    I would get him to agree to pay you for your time to trouble shoot. 1. Try connecting the lights to one of your own known to be good transformers and see what happens.. either the lights work normally or they still flicker.

    2. If he agrees to pay you, then you could disconnect one light at a time and see if upon disconnecting one, the flashing stops.
    if so.. you found your culprit.

    I doubt that there is any DC power supply at home depot... other than what might be made for LED tape light, which is usually run on DC.

    You mentioned quick connects... I'm wondering if somehow... whoever installed the system tied the end of the run together OR ran it back to the transformer and crossed polarity when returning to terminals. ( when amateurs do the work, there's no telling what crazy theories or practices or advice they followed when installing it).

    Anyway, hope you are able to figure it out. As far as the voltage reading on the transformer or the quick connects, that phenomenon could be caused by something to do with how it was wired incorrectly, a bad led , a bad quick connect - ie - short...

    Let me know what you find

  8. starry night

    starry night LawnSite Gold Member
    Messages: 3,321

    Bob and George, Good input by you guys. I am going to contact the customer and see if he is willing to spend a little more for troubleshooting. If he lets me take another look, I'll post the results.
  9. Spilllight

    Spilllight LawnSite Member
    Messages: 33

    Those Hampton Bays are electronic made to look like a magnetic. Using a volt meter will not give accurate readings unless the load is pulling through the power. The other issue is distance, often the fixtures can't be very far no more than ten feet with electronic which is awful for us. This may be the reason fixtures are flashing ( too far ) even bumping up voltage may not do the trick. Thus, the fixtures are not pulling the power through leaves you reading 0.00v. Replace trans.....
  10. starry night

    starry night LawnSite Gold Member
    Messages: 3,321

    If that Hampton Bay transformer is electronic, that might explain the peculiar issues in this trouble-shoot. Hmmmm........

Share This Page