LED Dimmer or Lamp Dimmer?
Problems and Solutions
LED dimmer or lamp dimmer
is about risks using an external
lamp dimmer with a LED - in
this case LED rope
- but the problem relates to other LED
lights as well as using a proper LED controller.
Recently had an enquiry from
Jared
about the suitability of
external LED dimmers, which I promised to post here
with my answer and other thoughts you will find interesting. And in
case you were wondering, he has a 5mth follow up after my reply too.
So this is how it started:
Jared
wanted to use a
Lutron
dimmer that he already bought for his LED rope
light. Because his problem relates to the use of other third party lamp
dimmers
with a LED light in general I post it right here. Read the thread below.
Taking care of strange
technical words in the post, like "PWM"
Jump to the FAQ
page for other
useful technical wording. >>
For those of you who don't know what PWM is: it is just short for Pulse
Width Modulation. Behind the fancy name is a digitally encoded light
output control. It regulates the cyclical peaks and lows of power -
called duty cycle - released to your LEDs via a special program often
hard-coded in a device called controller.
More
precise definition of PWM and other good resources at the bottom of
this page
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Using a lamp dimmer with your LED
light - possible risks
“I've
hooked up a Lutron
lamp
dimmer to my LED rope light and all seems to be
fine (I tested one for awhile before attaching the entire
series). The Lutron dimmer uses PWM technology and the rope
light plugs into a standard AC wall outlet (as does the lamp dimmer
which is why I selected that particular model -- to avoid hard
wiring).
The light rope manufacturer had nothing about
dimming on their packaging or instructions ...
... but did not recommend using
a dimmer with the LED light rope when I called customer
service. Since I assume some of their recommendation has to
do with liability, I would like to ask you, a neutral party: what are
my risks and if I reduce the life of my LED rope lights by doing this,
how much will it really affect them?
(will they work 9000
hours instead of 10,000 or more like 1000 instead of 10,000)?
Any other risks? Thanks in advance -- I appreciate
your feedback and will let you know how things go should I choose to
continue my experiment (at most I'm out about $150 but I prefer running
45w LED to 450w incandescent which is why I'm doing this).
I
wouldn't use a dimmer at all but I'm running the perimeter of my new
deck and without it the neighbors think I've opened a DISCO so I needed
to tone things down. (
Jared)
*********************************************************
Hi Jared,
As much as I want to help, I have to qualify my answer because I am not
a properly licensed electrical engineer. Problem of course that even
they don't know much about the 'fine print' on LED yet. And
If
you are a frequent at
FLL you probably know that besides running this site I am a building
information modeller and developer. So sorry to disappoint, but I
cannot confirm any
wiring or electrical
issues or give such proper advice.
That said, I find that
there
are many hidden issues with LED dimmers. So let's
see a controller
dimming first. This is what manufacturers recommend simply because they
work
on known operating points of the LED. (Still, each LED has individually
different ones as one crystal has slightly different hole mobility than
the other.)
But the controller still needs voltage to go through to read the knob
setting so there is a limit as to how low the dimming can go. You
cannot dim too low with a controller.
The other issue is with
selective
LED dimming. Primary colors usually dim
best that's the idea of RGB (Red-Green-Blue) color mixing. So if you
get a good
controller that dims and your rope is RGB, you should be able to not
just
dim but also color mix. This could be some good fun, if not
especially for a disco lighting as you say then
for a wild enough home party, which I highly recommend to spruce up
with all kinds of LEDs - in your case LED ropes.
The problem with external or third party controllers, especially buying
them online, is that
vendors
prefer the ones packaged with the product they have. (Guess there are
obvious
issues
with customer service as LED quality differs from model to model and
where they source it from.) So it may be harder for you to find a third
party
controller to use as a LED dimmer. Let us know if you have this
problem.)
That said, there are good folks who do recommend external LED dimming
because
it's proven practical for them. So I will not confirm or counter their
experiences, just list them.
Bottom Line?
When all done and dusted, your LUTRON with PWM could be a good solution
for what you seek. I doubt that anyone will be willing to bet how
shorter if any your LED will last. My hunch is that it will depend on
the differing quilities of LEDs in the string which is usually the case
anyway. But for the reasons mentioned I cannot confirm.
*********************************************************
Hello,
Just wanted to follow up and say I've been using this dimmer
for 5 months without any problems (also uing in conjunction with a
timer that turns on at dusk and off at dawn so there are many hours
logged already). It uses a slider switch which is a
bit touchy but otherwise not bad at all. Not a bad option for
anyone wanting to dim rope light from an AC outlet.
Last time I was at Home Depot this dimmer was only about $10.
Take care,
Jared
*********************************************************
Great input Jared, glad to have helped and thanks for the feedback ---
L.
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Related Articles,
Resources, Products:
The
FAQ page
has many of the other terms explained.
(links
open new window)
The LED rope light
mini site map
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