Underwriters Laboratories (UL), a product
safety certification organisation, is
developing a Safety Standard for LEDs used as
light sources in luminaries designed for sale
in the North American market.
As a first step, UL recently released
document UL 8750 entitled "Outline of
Investigation for LED Light Sources for Use in
Lighting Products." This will be used as the
main document within the certification
organisation for all investigations of the LED
light sources used in UL-listed lighting
products.
All UL customers are able to download the
Outline of Investigation (OOI) free of charge
by visiting UL’s standards portal at
www.ULstandards.com.
Other users can purchase a copy of the OOI
($356 for the PDF file) at www.comm-2000.com.
During the first quarter of 2007, UL formed
a balanced Standards Technical Panel (STP) to
work on the drafting and publishing of an ANSI
Compliant LED standard, using UL’s OOI document
as a starting basis. The panel consists of all
the stakeholders involved: manufacturers,
testing and standards organizations, supply
chain, electrical and building code inspectors,
government, consumer, general interest,
commercial / industrial users.
The purpose of UL's activities is that LEDs
used in any type of lighting products achieve
the same levels of acceptance and consumer
confidence as traditional lighting
technologies.
Safety issues UL says that LED
manufactures must consider the following three
important potential safety issues when
designing their products:
Risk of shock: For this purpose,
two kinds of applications are considered: LEDs
supplied by a Class 2 supply and those that are
either line connected or otherwise connected to
a non-Class 2 supply. The first group does not
present a shock hazard due to the voltage and
current limitation, while the second one will
need to comply with standard insulation and
accessibility requirements. The only additional
concern even for Class 2 supplies is for
devices used in wet location, which further
limits the maximum open circuit voltage to 15
VAC or 30 VDC.
Risk of fire: Many different
aspects will impact the performance of a
fixture (including, but not limited to:
proximity between the LEDs, diffuser design and
material, type of enclosure, installation,
etc.). While using a Class 2 power supply
reduces the risk of fire by limiting the
available electrical energy, there is evidence
that these systems may exceed 90 degrees C (the
maximum permitted by the building code in the
U.S. on combustible surfaces) due to the
thermal energy dissipated by the LED in
converting electrical energy to light.
Therefore, it is necessary that LED luminaries
are designed to take this into account and to
undergo temperature testing to ensure all
components within the luminary and the outside
surfaces are operating within their specified
temperature ratings.
Biological hazards: Issues like
retinal damage and other health issues that
could arise from exposure to these light
sources are always a concern, but currently
there is not conclusive research that proves
that there is a significant risk involved with
using this technology. As with any light
source, using a diffuser may mitigate personal
injury risks from the electromagnetic radiation
it produces.
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