installing led ucl

ranger481vsOctober 5, 2012

I installed LED strip lighting using a 60w transformer on a Lutron dimmer switch. I have a single run broken up into 4 sections in the following lengths (44", 44" 65" and 24") The last 24" section is at the end of the run, it has a much more noticeable flicker to it, even on full brightness. Is there anything I can do to fix/improve this issue? Thanks!

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David

If you're using a Maestro dimmer, there will be flicker.

An analog dimmer like the Diva would work very much better.

The dimmer has to be matched to the power supply. ie - Electronic Low voltage dimmer for electronic power supplies, MLV for magnetic power supplies.

    Bookmark   October 6, 2012 at 6:27PM
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ranger481vs

Thanks David. Yes, I am using a Diva dimmer. I'm wondering if it's a connection issue somewhere. Although, I did check to make sure all connections were secure, but I'm just not sure how good of a connection the fold-over connectors that slide on the ends of the LED strips are.

I purchased everything from Environmental lights. So far, I'm not too impressed. Aside from the 4th section having significant flicker problems right now, even when I only have the first three sections hooked up, they will flicker quite a bit in the range of about 55% to 20% dimmed. So, those dimming levels are unusable.

I'm enclosing an image of my wiring diagram so you can see how it's been wired.

Now that I have all the wiring done, I wonder if there is a better quality LED strip that won't flicker as much.

    Bookmark   October 6, 2012 at 9:20PM
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attofarad

It sounds like it could be a poor connection.

A local lighting store doesn't use those flaky connectors -- they solder wire leads to the strips and then use better connectors on the wire leads.

Which strips are you using, and what is their total power supposed to be?

    Bookmark   October 6, 2012 at 9:55PM
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attofarad

Ranger -- which Diva dimmer are you using?

    Bookmark   October 6, 2012 at 9:58PM
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David

Split the setup instead of having all the lights in series to see if there is an improvement.

You can lay out 3 separate runs to the power supply - mockup first.

Assuming 3w per ft and a total of 14', total power req should be ~42 w + 11w (20+% buffer) = 53w

    Bookmark   October 6, 2012 at 10:50PM
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David

If the bars are the high brightness variant, the power is 5w per ft.

Total: 5 *14 = 70W (bars only)
assuming ~ 25% spare capacity ~17.5W

Total power requirement 87.5W, round up to 88W.

    Bookmark   October 6, 2012 at 11:55PM
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ranger481vs

My diva model is DVLV-603P. Is there a different dimmer that might decrease the flicker?

I confirmed the installed strip measurements and it is indeed 14ft total (24", 60",45",41")

I do have the high brightness, so does this mean EL sold me a transformer that is underpowered for my system? It looks like their next size up transformer is overkill at 240W (4x60). Is it still worth mocking up the three different runs even though I only have a 60w transformer?

I appreciate the help.

    Bookmark   October 7, 2012 at 8:53AM
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David

Yes, it would be useful to mock up the 3 separate runs - the main idea is to figure out if there is a possible solution -such as having 2 runs off 1 power supply and another off a second. Both power supplies would be tied to the same 120V AC line and switch.

It is always good to have separate runs in parallel rather than in series.

    Bookmark   October 7, 2012 at 10:30AM
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brickeyee

You want to stay under 80% of the transformers rating, and try to feed the string from the middle, not one end.

In many cases a larger wire to feed from the middle is money well spent.

Dropping a volt or two on a 120 V circuit does not have much affect (less than 1%-2% voltage variation).

Dropping 1 V on a 12 V circuit is over 8% right away, (and almost 16% of the power).

The LEDs take DC. If they are fed a DC supply with a lot of ripple they will dim and even shut off when the voltage and current get lower than needed to operate the individual LEDs. They appear to blink very fast, often at 60 Hz or 120 Hz (depends on the power supply design). You can see the n\blinking if you sweep your eyes over them in dim light.
They will look like displaced dots of light in a line.

Blinking at much lower frequencies (every few seconds) usually means you have the wrong type of dimmer for the power supply.
This will quickly overheat and damage either the dimmer or the power supply (one usually fails before the other).

The blinking rate often varies with the dimmer setting.

As you try to dim further, the lights start to barely blink off and then blink off for longer ad slower times.

    Bookmark   October 7, 2012 at 10:41AM
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ranger481vs

Ugh. Okay, I am going to check back to EL to question why they suggested a 60W power supply for my system. Not sure why they didn't offer the 96W model, but I really hope they will exchange it for me, since they recommended the wrong size. Then, I will plan on rewiring three separate runs. I'll post an update afterward.

    Bookmark   October 7, 2012 at 11:41AM
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attofarad

Ranger, I missed it if you didn't say, but are you running 12V? I don't see any 96 watt transformer/supply for 12V, just 24V.

The linked 90 watt Technomagnet TMC90S12VDC transformer is available from a couple of sources. I got my 150w from http://ledwholesalers.com/store/index.php?act=viewCat&catId=107, and my 300W from Alcon Lighting. Or you could add a separate 40W or 60W to drive part of your lights.

If I understand correctly, these transformers are rated by input power, not output. They lose about 20% (~80% efficient), hence the warning to allow extra capacity.

Here is a link that might be useful: transformers - 12V

    Bookmark   October 7, 2012 at 3:34PM
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attofarad

Also, as Brickeyee says, voltage drop is much more of a big deal at 12V than at 120V. If you are delivering the same power, the current is 10x higher, and voltage drop 10x more critical as a percent of supply. So the wire resistance is 100x more critical than for a 120V circuit, if you want to keep the power loss down.

Even if the wire is large enough to handle the current without frying, resistive drop can cause dimming.

I ran a double run of #8 wire for my 200 watts of cove lighting (50 feet to the far end), and will use #14 to locally connect to the strips every 10 feet to minimize drops along the strips.

    Bookmark   October 7, 2012 at 3:52PM
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ranger481vs

I checked and found that my lights are the 3 watt variety, so the power of my transformer should be good.

I am planning to rewire using three runs; 1st run to first section, 2nd run to 2nd/3rd corner sections, and the last run to the 4th section. Does that plan makes sense? I also want to upgrade the wire size, so what gauge would you recommend. The longest run to the 4th section would be roughly 28ft.

Next, I would like to eliminate those fold-over connectors and solder all connections instead. I'm not really clear on how I would do this? Would I solder #14 wire to beginning of each strip, then solder that to the larger wire? How do I do this up to code? Is shrink tubing over these solder joints all I would need?

    Bookmark   October 9, 2012 at 10:20AM
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David

The environmentallights website has a wire gauge calculator. I would think 16 gauge is enough.

It might be better to have the transformer / power supply in the corner cabinet. In any case, do a mock up first using the exact wire lengths and gauge.

Why solder all the connections? The net result may not be an improvement as solder joints do crack ... (cold solder, shorts, damaged circuit traces, etc)

Here is a link that might be useful: wire gauge calculator

    Bookmark   October 9, 2012 at 12:22PM
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ranger481vs

I just did my mock up, and ended up doing 4 parallel runs. It definitely worked. All sections function identically to each other now. Thanks for the help with this.

I am able to dim down to 50%, but after that it still gets a little flicker going on. The salesman from EL thought it might be worth trying other dimmers, such as Lutron Maestro spec grade dimmer. Is that one worth trying? Any others that you might recommend, which would be available at a box store?

    Bookmark   October 13, 2012 at 5:27PM
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David

The Maestro (pn MA-R-WH) is a digital dimmer. Such digital dimmers don't work very well with LED.

Here is a link that might be useful: Lutron Maestro document

    Bookmark   October 13, 2012 at 7:50PM
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brickeyee

"Why solder all the connections? The net result may not be an improvement as solder joints do crack ... (cold solder, shorts, damaged circuit traces, etc)"

Correctly made solder joints still hold the reliability throne.

They are more time consuming to make, and require more skill.

All the various mechanical connections have been chasing after solder reliability for years.

Many now come close enough to be accepted and widely used.

    Bookmark   October 15, 2012 at 1:14PM
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