Page 22 - IEC Insights Jan-Feb2020

FEATURE
YOUR CONSTRUCTION
YOUR CONSTRUCTION
36,000 hours to L₇₀ ; this is the projected 339,304 hours. It doesn’t matter if one is schedule, ask your reps for the IES LM-
ACCOUNTING SOFTWARE
luminous flux maintenance life. projecting to L₇₀, L₈₀, or L₉₀; regardless, 80 reports for the LED packages, arrays
statistical confidence in the projection or modules integrated into this fixture ACCOUNTING SOFTWARE
TM-21’s intermediate steps can sometimes falls off dramatically beyond 6X. The most model. Your wall pack vendor claims
produce huge numbers (e.g. 315,518 relevant output from the TM-21 calculation 100,000 hours to L₇₀ but presents you
FOR
YEARS!
hours) that aren’t valid. Let’s set aside is called the Reported L70 value, a 10,000-hour LM-80 report? Call them FOR 35 YEARS!
the LEDs and pick up a ball. Just as you because it is capped at 6X. Calculated on it. Tell them you need the 17,000-
can be confident that a ball dropped from L₇₀ and Projected L₇₀ values, if reported, hour report and their TM-21 projection. 35 years of
your hand will land in a small circle you’re simply aren’t intended for designing a A streetlight manufacturer is hoping reporting, wow!
standing in, we can be confident in the lamp or luminaire, and TM-21 says so. you’ll spec their cobrahead rated
measured LM-80 data. Move that circle 250,000 hours to L₉₀? Let them know
10 feet back your confidence projecting I worked for an LED manufacturer for you’ll review the 42,000-hour LM-80
the ball into the circle goes down a bit. years, involved in LM-80 testing planning report. They don’t have it, and they’ll be
Move that circle another 20 feet and you and review. The longest credible and waiting to see if you cave. Don’t. Even if
might think you’ll land it (but I don’t). reported LM-80 test I’ve heard of is 18,000 they had such a report, what relevance
One hundred feet away, no matter how hours. For that reason, any projection would it be if the tested LED parts are
good a game you talk, hitting that circle longer than 110,000 hours doesn’t pass five years old and no longer sold? happ
is a bad bet. Setting aside the lousy the smell test with me. I round it off birthday,
comparison of human and semiconductor to 100,000: anything north of here is LED lifetime is unfortunately complex buddy! KEVIN
performance, it’s this same concept of suspicious and worthy of inquiry. Those and subject to gaming, but with some
confidence that sets up the one rule reporting 150,000+ hours to L₇₀ while basic principles and a back of the MIKE ODE
PRESIDENT
in TM-21 that is sacrosanct, called the referencing TM-21 are conveniently envelope calculation you can defend
“6X rule”. Unobserved, the entire TM-21 ignoring clause 5.2.5, the 6X cap. against overrated products. This year
standard is rendered meaningless. They are attempting to make money IES will publish ANSI/IES TM-21-19, the
from the uninformed. Unfortunately, first revision of this standard, and the
The 6X rule states “luminous flux values many other reputable manufacturers, accompanying ANSI-approved IES TM-21
must not be projected beyond 6 times not content to see competition eat Calculator. For more information please
the total test duration (in hours) of their lunch, feel compelled to play visit www.ies.org or email abaker@ies.org. CHAD
measured data”. If an LED manufacturer the same statistical games.
has reported 6,000 hours of LM-80 data, FRED ODE BRIAN
the longest legitimate projection at the Don’t be fooled. Defend your client and Alex Baker MSc, LC, IES, is the Manager of OWNER & CEO
bulb or fixture level is 36,000 hours, her project with a quick calculation. Government Affairs and Public Policy for
even if an intermediate calculation shows Especially for critical types on the fixture the Illuminating Engineering Society. Alex scheduling is
will be responsible for monitoring federal, a piece of cake!
state and local government agendas for
matters impacting IES members and the MELORA
lighting industry at large, maintaining
relationships with relevant government
offices and allied organizations and
coalitions, and for developing the Society’s MATT
long term public policies and strategies. AMAZING
AMAZING
MOBILE
MOBILE
CAPABILITIES!
The most relevant output CAPABILITIES!
from the TM-21 calculation
is called the Reported L70
value, because it is capped
at 6X. Calculated L70 and
Projected L70 values, if
reported, simply aren’t
WE’RE CELEBRATING
intended for designing WE’RE CELEBRATING
ALL YEAR LONG!
a lamp or luminaire, ALL YEAR LONG!
and TM-21 says so.
Figure E1. Graphic representation of lumen maintenance life projection using 6000 hours of LM-80-08 data.
VISIT FOUNDATIONSOFT.COM/IEC FOR A FREE DEMO, TODAY!
20 Insights Magazine | January/February 2020 | www.ieci.org