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pfrank
Starting Member

1 Posts

Posted - 05/14/2012 :  09:13:22 AM  Show Profile  Reply with Quote
Like others, I've encountered the issue that when attempting to use a controller on LED rope lights, the lights never go completely out -- just a low dim. For the application where I have the rope lights (above kitchen cabinets) I don't mind this, as they "disappear" during the day and provide a soft glow at night even when in the off position.

My questions: Since the LED rope light won't dim to a full off position, is it safe to leave these lights permanently on? They're supposed to last 100,000 hours (11+ years) and there is no heat from them since the're LED, so I don't mind... just want to be safe.

Thoughts?

Tfitzpatri8
Administrator

USA
10615 Posts

Posted - 05/14/2012 :  10:32:45 AM  Show Profile  Reply with Quote
As you no doubt already read in those other threads, small LED loads don't put enough of a load to overcome the 'load sense' feature on plug-in modules. To make the dim glow go away, or use a wire-in module or switch that doesn't have that load sense feature.

If you like the glow and the load you are using doesn't flicker, I see no downside to just leaving it be.

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Geo
Advanced Member

Canada
789 Posts

Posted - 05/14/2012 :  3:35:38 PM  Show Profile  Reply with Quote
As mentioned many times here, just a small incandescent light or some other small load in parallel with the LED will get rid of the glow.
LEDs DO generate heat just like any other load. The biggest problem with LEDs intended to replace incandescent light bulbs is how to dissipate their heat. In your case, however, because the current is quite low, the LEDs will not heat up noticeably above the ambient temperature.
Incandescent light bulbs have limited life, usually around 2,000 hours, but that depends on how much current flows through them. For example, if you put two 7W bulbs in series, the total power consumed will be 1.75W and the life of the bulbs will be around 50,000 hours.
I'm using quite a few dimmers in my home - by reducing the lights' voltage even slightly, the lower light level may be imperceptible, while the power drain drops at the square of the voltage reduction and the life of the bulb increases significantly.

GJN
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Sammer
Junior Member

USA
38 Posts

Posted - 05/15/2012 :  09:01:27 AM  Show Profile  Reply with Quote
quote:
Originally posted by Geo


LEDs DO generate heat just like any other load. The biggest problem with LEDs intended to replace incandescent light bulbs is how to dissipate their heat. In your case, however, because the current is quite low, the LEDs will not heat up noticeably above the ambient temperature.

There is a reason for some confusion here. As efficient as LEDs are they are not 100% efficient so some electricity is converted to heat. However LEDs unlike incandescent or fluorescent lights can not radiate heat so another way must be found to dissipate that heat (the LEDs must be cooled) or the life of the LED light bulb will be greatly reduced.
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mistrip
Starting Member

1 Posts

Posted - 05/17/2012 :  6:38:04 PM  Show Profile  Visit mistrip's Homepage  Reply with Quote
No, it's not safe. The LED can last 11 years, but the materials such as the rope plastics, can't last for a long time.
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Tfitzpatri8
Administrator

USA
10615 Posts

Posted - 05/17/2012 :  6:53:26 PM  Show Profile  Reply with Quote
Citation needed. I haven't seen any safety issues with LED rope lighting or any guidance to remove them after any particular number of hours of service on a dimmer. Where are you seeing something different?

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oberkc
Advanced Member

USA
3707 Posts

Posted - 05/18/2012 :  09:56:30 AM  Show Profile  Reply with Quote
quote:
Citation needed.


Agreed. My experience with rope lighting is contrary to this. I have rope lighting that is outside (no direct exposure to rain/snow or sun) and has been so for over ten years without any apparent problems with the rope plastics. Furthermore, I am not even sure that degredation in the rope material would be cause for failure of the LED string.

Like many physical devices, however, life is very dependent on the environment. I would imagine that the biggest factor would be UV rays from the sun.
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stusviews
Advanced Member

USA
15854 Posts

Posted - 05/18/2012 :  10:50:09 AM  Show Profile  Visit stusviews's Homepage  Reply with Quote
More that two years outdoors in sunny SoCal.

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Geo
Advanced Member

Canada
789 Posts

Posted - 05/19/2012 :  11:29:55 AM  Show Profile  Reply with Quote
I've also had them for 10+ years outside without a problem. I did some work in Barbados where they have them all over the place, also around pools, exposed to the sun. I heard no complaints.

GJN
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Geo
Advanced Member

Canada
789 Posts

Posted - 05/19/2012 :  11:32:52 AM  Show Profile  Reply with Quote
BTW, where does the 11 years life span come from? When the first LEDs came out in the seventies (by Monstanto) I built a couple of projects with them. They still work!

GJN
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Geo
Advanced Member

Canada
789 Posts

Posted - 05/23/2012 :  06:40:41 AM  Show Profile  Reply with Quote
Out of curiosity I calculated, using the HDBK 217 model, the failure rate of an LED - the type used in rope lights. It comes at a whopping 2.208E-3, which translates into 4.529E8 hours MTBF (mean time between failures) or 51,700 years. If the rope contains 100 LEDs and a failure of any one makes the rope useless, then statistically the life of the rope is 517 years. Even if we add some unknown environmental factors, chances are we won't live long enough to see it die except due to a damage.

GJN
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Vulsion
Starting Member

USA
1 Posts

Posted - 12/18/2017 :  12:35:24 PM  Show Profile  Visit Vulsion's Homepage  Send Vulsion an AOL message  Reply with Quote
The 100,000 hours (11+ years) for LED are mostly for marketing. This is why the majority of rope light come with only 1 year warranty. These type of dimmers should work for you:
https://www.aqlightinggroup.com/rope-light/ropelight-accessories/controllers/7-function-chasing-3-wire-incandescent-rope-light-controller/
https://www.aqlightinggroup.com/rope-light/ropelight-accessories/controllers/led-2-wire-dual-channel-rope-light-dimmer/

Kevin Tamaki
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stusviews
Advanced Member

USA
15854 Posts

Posted - 12/18/2017 :  3:42:07 PM  Show Profile  Visit stusviews's Homepage  Reply with Quote
quote:
Originally posted by Geo

Out of curiosity I calculated, using the HDBK 217 model, the failure rate of an LED - the type used in rope lights. It comes at a whopping 2.208E-3, which translates into 4.529E8 hours MTBF (mean time between failures) or 51,700 years. If the rope contains 100 LEDs and a failure of any one makes the rope useless, then statistically the life of the rope is 517 years. Even if we add some unknown environmental factors, chances are we won't live long enough to see it die except due to a damage.


MTBF is to be understood for what it is, in particular, if you were to bet how long most of the products will endure, then that's your best bet.

But is usually misunderstood to be how long the item you have actually will last.


Stu's Views is Education and Fun. What do YOU want to VIEW today?
MathLandia High school mathematics learning fun.
Both Stu's Views and MathLandia are free websites that do not sell anything.
Saving energy is not always free. Be a world saver.


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Geo
Advanced Member

Canada
789 Posts

Posted - 12/20/2017 :  2:37:04 PM  Show Profile  Reply with Quote
I should have used MTTF (mean time to failure - see above) as LEDs are not repairable. At any rate, without going into statistics, the failures are distributed over a curve. Consequently, you may find one LED failing within the first hour of its use or another one lasting for (almost) eternity. It also depends on operating temperature, modes of operation, etc. Typical indicator incandescent lights have their life expectancy 8,000 hours. By lowering their operating voltage by about 20% you can meet military requirements of 50,000 hours. When it comes to LED bulbs the life is more often than not limited by their electronic drivers which, depending on the light fixture, might be operating near their maximum junction temperature.

GJN
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