This document provides a summary of a presentation on color, dimming, and flicker issues related to LED lighting. It discusses key topics like color temperature binning strategies, types of dimming and control methods for LEDs, and causes and solutions for flicker. The presentation aims to help lighting designers better understand these technical topics and how to specify LED systems that perform as intended.

1. Designers Light Forum
One Designer to Another
Color, Dimming, and Flicker in the Age of LEDs
Kenny Schutz, LC, IES, PMP
Principal, Focus Lighting
March 28, 2017

2. Credit(s) earned on completion of
this course will be reported to AIA
CES for AIA members. Certificates of
Completion for both AIA members
and non-AIA members are available
upon request.
This course is registered with AIA CES
for continuing professional
education. As such, it does not
include content that may be deemed
or construed to be an approval or
endorsement by the AIA of any
material of construction or any
method or manner of
handling, using, distributing, or
dealing in any material or product.
___________________________________________
Questions related to specific materials, methods, and
services will be addressed at the conclusion of this
presentation.

3. Learning
Objectives
1. Recognize and Avoid two leading causes of color variation.
2. Identify the characteristics, pros, and cons of three major dimming & control methods.
3. Understand the role of the driver in dimming performance and flicker.
4. Learn specific strategies for designing successful specifications.
At the end of the this course, participants will be able to:

4. One Designer to Another
Color, Dimming, and Flicker in the Age of LEDs

5. Color (White)
It’s really important to me that that all of the [white] colors match. So let’s go with
2700K for all of the LEDs. -- An Interior Designer while reviewing a submittal.
Color Temperature and Binning

6. But these are all 2700K…

7. White
• “White” is a range from “warm”
to “cool.”
• CCT (Correlated Color
Temperature)…°K
• Plotted on “Black-body curve”
• Warm (≤ 3000°K), Cool (≥4000°K,
or 4500°K), Neutral in between.
• CCT is not Chromaticity

8. Color Temperature
• Each CCT is also a range.
• ANSI standard allows variation

9. Color Temperature
• The color of the “white” may not match
• Manufacturer to manufacturer
• Product to product (within a manufacturer)
• One version of the product to the next
• One order to the next

10. Color Consistency - Binning
• Manufacturing produces
unavoidable variations.
• Binning = sorting LEDs to
minimize variations.
• Wider bin = less cost and faster
lead time…but more variability.

11. Color Consistency - Binning
• ANSI c78.377-2008 defines
color bins as parallelograms
that enclose a 7 step MacAdam
ellipse on the 1931 CIE color
space

12. Color Consistency - Binning
• ANSI c78.377-2008 defines color bins as parallelograms that enclose a 7
step MacAdam ellipse on the 1931 CIE color space

13. Color Consistency – Binning Strategies
1. Buy one or a very small number of bins. Easy & Expensive.
2. Specify just CCT (and flux). LED chip manufacturer mixes on behalf
of customer to match a bin color.
3. Buy a large portion of a
production run and the lighting
fixture manufacturer develops
expertise in mixing them
together. Cheaper & Harder.

14. Color – What To Do
• Understand what color temperature really is.
• Get into the details.
• Know the manufacturer’s binning strategy
• Specify manufacturers who will track & can repeat a bin and offer a
color shift warranty
• Trust your eyes (not graphs)
• Look at samples

15. Dimming
I’m sick and tired of my LEDs not working. They flicker. They don’t dim. They look
bad. I’m constantly told it’ll work fine. When I ask the designer, they just say, “well,
you didn’t buy what I specified.” So, fine. I’ll guarantee that we’ll get what you
specify. You have to guarantee it’ll all work.
-- VP of Design & Construction for a large casino, at a project kick-off meeting.

16. Dimming
This LED lamp draws only 7w. What do you mean I can’t put 142 of them on a
1000w dimmer?
-- A lighting designer

17. Dimming & Control
“Dimming”
• Controlled variation in the output (brightness) of lighting fixtures.
• Not necessarily done with a dimmer
• Better term: Control
• Controller “talks” to a dimmer or directly to a driver

18. Control
Dimming & Control
• Controlled variation in the output (brightness) of lighting fixtures.
• Not necessarily done with a dimmer
• Better term: Control
• Controller “talks” to a dimmer or directly to a driver

19. Control
Control
Dimmers
“Dimming”
Drivers
• Dimmer regulates power to driver.
• LEDs have corresponding output.
• AKA “Line/Primary side dimming”
• Non-dim power
• Driver regulates power to LEDs.
• Driver responds to low voltage signal.
• AKA “Load/Secondary side dimming”

20. Control - Dimmers
Control
Dimmers
DigitalAnalog
“Dimming”
Drivers
• Analog dimmers reduce voltage
but are no longer used.
• Digital dimmers reduce power
with high-speed switching.

21. Digital Dimmers
Digital Dimmers:
Phase Cut, 2-Wire
Forward Phase,
Leading Edge
TRIAC, SCR
Reverse Phase,
Trailing Edge
INC
MLV
ELV

22. Dimmers – Min. & Max. Load, In-rush & Rep Peak
• From a dimming manufacturer’s App Note: Many [of our] products provide
minimum and maximum load ratings in Watts (W)… These ratings are
based on traditional light sources (incandescent and halogen lamps) and do
not apply to LED and CFL loads.
• E-mail from a prominent LED lamp manufacturer: We recommend de-
rating the dimmers because of the in-rush current…with a factor of 5 - This
means that for a 500W dimmer, our estimate would be a maximum of
100W of LED line voltage lamps.
• From another prominent manufacturer’s dimmer compatibility info:
Due to an electronic characteristic known as Repetitive Peak Current, which
results from inrush current at the phase cut, [our] downlights should be
treated as a 75W load for sizing purposes when used with dimmers.

23. Control - Dimmers
Control
Dimmers
Analog Digital
Forward
Phase
Reverse
Phase
“Dimming”
Drivers

24. Control – Dimmable Drivers
Control
Dimmers
Analog Digital
Forward
Phase
Reverse
Phase
“Dimming”
Drivers
“Dimmable”
Drivers Dimmable Drivers
• Powered from a dimmer and the
corresponding level is output from the LEDs.
• Must match dimming method.

25. Control – Dimming Drivers
Control
Dimmers
Analog Digital
Forward
Phase
Reverse
Phase
“Dimming”
Drivers
“Dimmable”
Drivers Dimmable Drivers
• Powered from a dimmer and the
corresponding level is replicated in the LEDs
• Must match dimming method.
Dimming Drivers
• Powered from non-dimmed circuit
• Gets instructions from Controller
• Does the dimming

26. Control – Dimming Drivers
Control
Dimmers
Analog Digital
Forward
Phase
Reverse
Phase
“Dimming”
Drivers
Analog
0-10v
Others
Digital
Others
DMX
“Dimmable”
Drivers

27. Control – Dimming Drivers
Control
Dimmers
Analog Digital
Forward
Phase
Reverse
Phase
“Dimming”
Drivers
Analog
0-10v
Others
Digital
Others
DMX
“Dimmable”
Drivers

28. (3) Control Methods Compared
2 WIRE 0-10v DMX
TYPE Dimming Control Control
DIMMING LOCATION Dimmer Driver Driver
AKA • 2-Wire
• Forward/Rev. Phase
• Leading/Trailing Edge
• 4-Wire
• Current Sinking
• “Low Voltage Dimming”
-
DEFINITION n/a IEC 60929 Annex E
(Note: ANSI/ESTA E 1.3)
USITT DMX512-A
DIMMER COMPATIBILITY • Requires Testing • n/a • n/a
SYSTEM COMPLEXITY • Simplest • Moderate • Relatively complex
ZONING • Fixed.
• Determined by power
wiring
• Fixed.
• Determined by 0-10v
wiring.
• (1) zone per pair of
wires.
• Flexible.
• Up to (512) zones per
wire run.

29. (3) Control Methods Compared
2 WIRE 0-10v DMX
INSTALLATION • Easiest, Least expensive
• Known by all ECs
• Requires additional pair
of wires for control
• Known by most/many
ECs
• Requires Belden, Cat 5e,
or similar for control
• Less familiar to ECs.
(Note: Low Voltage
contractor on large jobs)
CONTROL WIRE
MAX. DISTANCE
• n/a • 300’ (w/ 18ga wire)? • 1000’ – 3000’+,
it depends…
CONTROL WIRE
MAX. DEVICES
• n/a • Determined by driver &
controller
• 32 devices, as per
standard.
CONTROL WIRE
SPLICING
• n/a • OK • Limited.
• May require additional
equip.
CIRCUITING • Determined by load
size, zoning desired,
dimmer capacity (load &
in-rush).
• Determined by load
size, relay/breaker
capacity (load & in-rush)
• Determined by load
size, relay/breaker
capacity (load & in-rush)

30. (3) Control Methods Compared
2 WIRE 0-10v DMX
NOTES • Not originally designed
for LED loads.
• Problems occur at low
levels and small loads.
• Testing with actual
dimmer and actual load is
critical.
• Not all drivers follow
the standard.
• Don’t mix standards
• Theoretical inconsistent
levels and/or popcorning
possible because of
voltage drop on long runs.
• Requires relay to get
zero output and/or kill
power to driver.
• May require calibration.
• Requires Addressing.
• RDM addressing
available.
• Requires relay to kill
power to driver.
INSTALLATION ISSUES • Polarity matters
• Proximity to line voltage
& Shielding
• Wire colors matter
• Proximity to line voltage
& Shielding.
• Wire configuration not
100% standard.

31. Dimming & Dimmable Drivers
But the cutsheet said it’ll dim down to 10%...
-- Almost everyone.

32. Drivers
• LEDs = Low-voltage, DC, current driven devices
• Drivers transform, rectify, and regulate
• Determine LED dimming performance.

33. Dimming Drivers and Perception
• The 10% Dimming Driver
• LED output reduces in linear ratio
with current reduction
• Visual perception is logarithmic
• 10% output looks like 32%

34. Control & Dimming – What To Do
• Decide at the beginning of the project:
o How much dimming performance you need.
o Which dimming methods will be used.
o Determine compatibility early.
• Specify the drivers you want & need. Don’t go cheap.
• Only use brands you trust
• Ask manufacturers about compatibility.
• Get the manufacturer’s help
• Test!

35. Flicker
Low-frequency flicker can induce seizures … [and] has been linked to headaches,
fatigue, blurred vision, eyestrain, and reduced visual task performance…
-- U.S. Dept. of Energy

36. Flicker
• Primarily a function of the LED driver.
• Measuring and reporting flicker is not standardized.
• “In the absence of flicker metrics…LED systems should always be
visually evaluated.” -- DOE
• Dimming an LED source can increase or induce flicker
• All AC-powered sources flicker.

37. Flicker – Causes - AC to DC conversion

38. Flicker – Causes - Digital Dimming
• Digital / Phase Dimmers by definition create flicker.
• At lower levels, the “off” time is longer and flicker more visible
• LEDs, unlike incandescents, respond instantly to power fluctuations

39. Flicker – Causes - Other
• Not meeting the minimum load requirement of a dimmer
• “Dirty power”
• Harmonics (created when many electronic devices are powered
together)
•

40. Flicker – How to See It (Even when you don’t)

41. Flicker – How to avoid it
• Know your application and tolerance.
• Choose high frequency and low %
flicker.
• Get info from manufacturers.
• Dimmer adjustments.
• Tests & mockups.

42. The Big Take-aways:
•Test Test Test. Trust your eyes. There’s no good
alternative. Get support from clients and
manufacturers. It’s in their interest too.
•Specify. LED + Driver + Controls/Dimming. Be specific
and complete. Anything less is leaving it to chance.
•Take Charge. Coordinate and communicate with
everyone about anything impacting your design.

43. This concludes The American Institute of Architects Continuing
Education Systems Course

44. Thank you!
Kenny Schutz

45. Driver Acronyms
• CC – Constant Current – Driver that maintains steady current output to LEDs (make
sure you have the right current, e.g. 350mA) and varies the voltage to suit the LED(s).
Used with individual LED fixtures. Qty & wiring of LEDs can change the driver you
need and must be determined in advance.
• CV – Constant Voltage – Driver that maintains steady voltage output to LEDs (make
sure you have the right voltage, e.g. 24VDC). Can output up to rated wattage of the
unit. Used with linear LEDs where length (quantity) can vary.
• CCR – Constant Current Reduction – A method of dimming LEDs used in CC drivers.
Similar to analog dimming. No flicker. But not good at dimming deeply
• PWM – Pulse Width Modulation - A method of dimming LEDs used in CC and CV
drivers. Similar to digital dimming. Good for deep dimming. On & off, so it flickers
and must be done at high speeds to be good.
• mA – milliamps – 1/1000th of an Amp. 700mA = 0.7A
• Vf – Forward Voltage – minimum voltage LED must receive to light up.

46. AC Sine Wave