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Thread: Erratic LED Lighting

  1. #11
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    I just looked at the installation instructions and it is not clear about which is the load and which is the line, suggesting no electronics inside, as would be the case with a regular switch.

    Still, as an experiment, I would try swapping them.
    Cheers and Stay Safe,

    Marky the Sparky

  2. #12
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    Quote Originally Posted by K8MHZ View Post
    OP says all the lights are on the same circuit.



    So, I doubt it's a problem with the neutral.
    I read the post, I would look into the neutral.

  3. #13
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    Quote Originally Posted by iwire View Post
    I read the post, I would look into the neutral.
    What would be your reasoning? How would a bad neutral cause lights to get brighter and never turn off?
    Cheers and Stay Safe,

    Marky the Sparky

  4. #14
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    Quote Originally Posted by Fulthrotl View Post
    any chance you have a loose neutral somewhere
    in the mix? it's a long shot, but....
    The thread starter mentioned all the lights are on the same branch and the interaction originates from devices on the same branch. Dimmers fire twice per AC line cycle, 120 times per second. Neutral influence from other phases can cause misfiring but in this case it doesn't involve influence on neutral from another pole.

    Dimmers that require neutral takes all the timing reference from which to advance or retard the timing but those designed for highest wiring compatibility are designed to function in switch loop configuration.

    Quote Originally Posted by Fulthrotl View Post
    those dimmers are particularly tolerant
    Your perception of my opinions of LEDs don't change the fact that this is a technical challenge.
    http://www.apec-conf.org/Portals/0/I.../2016/1053.pdf

    The relationship between input Vrms and output Vrms present at incandescent lamp as well as its dimming behavior is absolutely predictable.
    The only function of a phase cut dimmer is advance/retard timing referenced to zero crossing. Different LED ballasts behave differently with different waveform even if RMS voltage is the same.

    Notch, spike that's present in power line that occurs during the on cycle passes right onto the load even if the dimmer is unaffected, but what happens to the light output depends on each LED ballast design. When an inductive load is switched off, it produces a spike. Just as I mentioned earlier, the LED ballast used in some LED lamp will flip out, shut off and restart like the original "CREE LED light bulb" or flash even if not used with a dimmer.

    The effectiveness of notch and spike dampening is entirely up to the LED ballast. The time constant of household incandescent lamps are extremely well known and very short transients get dampened out to avoid illumination quality issues. Most electronic ballasts have a capacitor for the DC link. The size and inrush current mitigation depends on each design and this is just as applicable to ballasts for the LED type load too.

    Quote Originally Posted by Fulthrotl View Post
    take one of those dimmer out of the mix, and substitute
    a lutron diva c-l, and see how it works. DVCL-153P
    This is a DIY project, but you're echoing my point. This takes time and projects known for high chance of complication adds time and therefore cost. The cost of products also goes up. Obviously, LEDs are much needy products and require vastly more technical support resources to support installers.

    and yeah, you can save some money on your electric bill.
    if i turn on every led in my house, and dim them all the
    way down, they draw total, about 40 watts, measured with
    a fluke 345.
    Hypothetical situation assuming whatever non-LED solution would be left on all the time. You don't know the nor does the customer so you have to guess and BS some but LED sales advisers tend to fill the blanks with ridiculous numbers to project positive ROI in a single digit years.

    It's important to distinguish kWh, $ and service type. Favorable words about savings from PG&E and SCE users on residential kWh tiered structure is totally meaningless. One of them seems to be in PSE territory which is about as low as power gets.

    electric-light has some strong opinions about LED lighting
    I don't think anything I said in this post is an opinion.

    Quote Originally Posted by Jim M426 View Post
    Thanks for the replies. I've had many of the same thoughts about possible problems. The wiring is good, I've checked it several times to see if there was any installation problems I missed. Everything tells me it boils down to the dimmers and LEDs.
    But what about the model(s) of the lamp/fixtures?
    Does the flashing occur regardless of the dimmer setting on the load that flashes or only when it's very low?


    Quote Originally Posted by Jim M426 View Post
    So everything works fine until I install the lights in the lanai and at the bar. Both the latter are 4" trims, as opposed to all 3" trims previously installed. Something quirky in manufacturing the 4" trims?
    Not about 3" vs 4". Just whatever LED ballast used in that engineering revision of whatever product you have.

    The other difference is the lanai and bar are each single pole switched. Could the companion dimmers on the 3-ways be working to stabilize the current? That would be something I'd have to take to Lutron but I wouldn't expect any eureka response.
    Where is the dimmer getting power from? If it doesn't tie into a neutral, the only way is through through the load. The "companion dimmer" is an electronic device, so it too requires power.

    In my last house I turned to the Maestro dimmers because I wanted dimming control at all locations and became hooked. All the lights there were incandescent. I had over (70) 6" cans with 65W lamps in that house and my electric bill showed it. After installing the LEDs here, I've barely noticed the bill increase. But I was skeptical about dimming LEDs to the low level I like in the evening. The Maestro dimmers allow me to program the dimmers to get to that level. All looked good until I added the last lights.
    The low-end limit isn't determined exclusively by the dimmer. The circuitry of the ballast used in the lamp/fixture has a greater influence but they both affect it. The lowest level you can reach may not start up if you were to shut off at that level.

    Disconnecting the bar and lanai lights, and no problems. But the problems have all been in the lanai lights. Those are the ones that, when dimmed, brighten up when adjusting dimming for the kitchen ceiling lights. They are the only switched sets that have 6 lights on them. But the lanai lights (all 4") is the only set that never turns fully off. The dimmer has a tab on the bottom of it that is supposed to completely cut the power to the fixtures, designed for changing out a lamp. When I pull the tab out, the lanai lights remain in the same dimmed state. So there is still a trickle current there. That tab is designed to completely open the circuit, cutting the trickle completely. That's not happening.
    Indefinitely or under a minute? It's normal for some LED based lights to glow at extremely low level for some time after powering down as the capacitors in the ballast discharge.

    I'm going to have measure the current at each fixture through all states of dimming and once the tab is pulled and see what comes up. I think the dimmers are affecting one another through the trickle current. I don't think there's a bleed over through the wiring but that tab issue has me wondering.
    If grounding is not proper, voltage can appear between frame and neutral.

  5. #15
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    Quote Originally Posted by K8MHZ View Post
    What would be your reasoning? How would a bad neutral cause lights to get brighter and never turn off?
    Experience tells me to do my own research. When I go to troubleshoot something I listen to what the users or other troubleshooters have to say but I take it with a grain of salt and start from scratch.

    If you have one thing affecting another that typically means something is in series instead of parallel. That being the case mis-connections of a neutral would be a good place to start and easy to spot.

  6. #16
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    Quote Originally Posted by iwire View Post
    Experience tells me to do my own research. When I go to troubleshoot something I listen to what the users or other troubleshooters have to say but I take it with a grain of salt and start from scratch.

    If you have one thing affecting another that typically means something is in series instead of parallel. That being the case mis-connections of a neutral would be a good place to start and easy to spot.
    So it's methodology, instead of having knowledge of a bad neutral causing problems like this on a single circuit. That's fine, I was just wondering.
    Cheers and Stay Safe,

    Marky the Sparky

  7. #17
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    Quote Originally Posted by K8MHZ View Post
    So it's methodology, instead of having knowledge of a bad neutral causing problems like this on a single circuit. That's fine, I was just wondering.
    Oh, well thanks. I am glad you are OK with it.

  8. #18
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    Quote Originally Posted by iwire View Post
    Oh, well thanks. I am glad you are OK with it.
    To be honest, I was just being polite. In all actuality, I think looking for a bad neutral before checking voltages at the switch would probably be a waste of time.
    Cheers and Stay Safe,

    Marky the Sparky

  9. #19
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    I haven't been able to do any troubleshooting but while I was installing the two 4" trims over the bar (just repainted the ceiling) I noticed that when I plugged them in they were unlit. As I installed them in the can (held by 3 spring tension clips) the lights lit. When I moved one a bit, the light went off. Same with the other. So it looks like the ground is completing a trickle circuit.

    I could easily isolate the spring clips and be done with it but I want to know what's going on here. Problem is the wife has me on kitchen cabinet duty - I suggested we dump the old doors and drawer fronts and I'd make new ones. I got as far as removing the doors and building new cabinets for the oven, cooktop and frig when the alarm was sounded announcing the newly applied ceiling paint (living room, dinette and kitchen) was wrong.

    Anyway, at least I know it has something to do with the ground. The LED trims each have their own driver built in to the trim. Who knows what is going on inside that? Probably someone in China.

  10. #20
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    Quote Originally Posted by Electric-Light View Post
    If grounding is not proper, voltage can appear between frame and neutral.
    As I mentioned before, I come from the land of conduit where we had a metallic ground throughout. In this instance, there is no metallic conduit beyond the panel but there are some metallic boxes previously installed. Everything I have installed with this lighting circuit is plastic boxes, plastic conduit and NM cabling. Because of this, I was anal with the grounding.

    When I replaced the panel, I installed a grounding bushing on the 2" EMT connector because I was using concentric KOs in the panel tub. From there I ran ground wire to ground bus that were screwed into the panel tub. I even scratched off the paint behind the ground bus. Probably overkill but from all I had seen here I wasn't taking any chances. What I don't know is the integrity of the 2" EMT as it leaves the panel and travels about 50' across the attic to a 200A disconnect breaker. There is no ground wire in that conduit. I did check the locknuts and they are tight.

    But...

    At the time I replaced the panel, I opened the 200A breaker in the disconnect. It didn't "snap" into the open position but rather slid to the open position. I thought the breaker was bad but I put a wiggy on the load side and both legs showed open. But because the hold was non-existent, I installed a lockout on it just in case.

    What I'm saying is this is an old house and from everything I have seen there have been a lot of fly-by-night "electricians" who have left their mark. I may need to check the ground integrity all the way back to the ground rod. No copper plumbing feeding the house here.

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