signs, incorporate radioactive materials such as tritium gas as a light
source.Their brightness level is very low, that is 2-3% of the minimum
level required for an electrical sign. However, they are safer and easier
to install in hazardous/explosion-proof environments such as coal
mines, natural gas installations, etc. As these signs are not electrical
signs, they are not subject to CSA standards such as C22.2 No. 141.
Electrical Signs (connected to a source of power) differ from battery
units in that they shall be illuminated at all times during normal AC
operation, and not only upon loss of AC power. This has a direct impact
on the admissible energy consumption referenced in government
regulations (National Resources Canada NRCan, CSA C22.2 No.
141), which is a maximum of 5W per legend single or double face.
A legend is defined as a single word, either “SORTIE” or “EXIT”or
“PICTOGRAM” There are also bilingual Exit Signs with: “SORTIE EXIT”
or “EXIT SORTIE”, quite common in applications such as airports or
federal buildings. A bilingual Exit Sign is acceptable up to a maximum
of 10W. The legend must also meet visibility standards including:
dimensions, average brightness, uniformity, background contrast
ratio. The most popular light source is based upon solid state LED
technology, which is capable of meeting both lumen output and energy
efficiency requirements.
A well established fixture type, the combination unit or “combo”,
includes both a small battery-powered Emergency Lighting unit and
an AC/DC Sign. An economical and easy to install alternative (installs
to a single electrical box), the combo offers both a Sign indicating
the direction of egress as well as emergency lighting on the path of
Does CSA C860 standard apply to all Signs, and in all applications?
Actually, there are no exceptions. Compliance is required in all cases,
even though the solution may be hard to find. For example, equipment
for use in hazardous locations, such as areas classified under Class
I, Division 1 (or Class I, Zones 0 and 1), defined as locations where
flammable gases, vapors or liquids are present frequently or under
normal operating conditions.
Two different methods are used to illuminate the legend. The most
common is found in back-lit signs, which use a light source located
behind the legend, illuminated through a diffuser panel. The other
method uses a clear, white or mirrored plastic (acrylic) face panel
on which the legend is etched or silkscreened or a film into a clear
panel. The light source is installed in the top portion of the panel.
Light is transmitted from the top edge of the panel, which is where
the “Edge-Lit” Sign gets its name from. In general, back-lit Signs
are more economical and provide more uniform illumination of the
legend. On the other hand, acrylic Edge-Lit Signs are considered more
high-end, elegant fixtures.
Required luminaires are designed specifically to meet CSA standards
for explosion-proof equipment. The heavy-duty luminaires are rated
for lamp wattages ranging from 50-250W. Constructed of die-cast
aluminum, the units feature a resistant prismatic glass globe
providing hemispherical light distribution. Until now, because of these
characteristics, traditional Signs were using 15-25W incandescent
lamps in order to provide sufficient illumination of the legend.
Conversely, an LED Sign is typically rectangular and relatively thin
(4-8cm) with an axial light source consisting of a line of LEDs to
provide indirect illumination of the legend through multiple reflections.
So, how is it possible to develop an LED Sign that meets NRCan/C22.2
No. 141 using a bulky heavy-duty luminaire dedicated to hazardous
locations Class I, Division 1?
Three types of fixtures are available for emergency lighting applications.
The first type is the Self-powered Sign, with a rechargeable battery
for emergency mode operation. Next is the Remote Sign, or AC/
DC Sign: in addition to a normal AC power supply, it includes a DC
input (6VDC, 12VDC, etc.) for remote power supplied by from a
separate battery backup. Installation of such Signs requires DC wiring
between both fixtures. Finally, the AC-only Signs are for applications
where emergency power is supplied from an AC Central System.
A variation on Sign design uses photo-luminescent materials for the
legend (letters and/or background). According to the National Building
Code, photo-luminescent Signs must be continuously illuminated by
a dedicated light source connected to an emergency power supply.
The Thomas & Betts R&D group has found a solution and
developed a special LED lamp series that is easy to install in
the lamp base of explosion-proof type luminaires. This special
LED lamp consumes less than 5W in either AC or DC current
of high performance LEDs configured in a unique pattern.
Horizontal distribution is 360 degrees radially and vertical
distribution is directly focused on the sign legend. This innovative
design meets the visibility criteria on standard size legends, while
limiting power consumption to between 3 to 4.7W per Sign.
In addition to electrical Signs, there are power free, self-luminous
LED lamps are dedicated to various voltage ratings: 6V, 12V, 24V or
120V and operate on DC and AC, supplying power to the Sign from
emergency lighting unit equipment or central AC or DC systems.
Lamps are listed/certified CSA C-US to CSA T.I.L. B-69 and UL1993
standards for LED technology based lamps or lamps with integral
ballast. This further reinforces the assurance of performance and
safety of the Signs using these lamps. The new Sign series from
Thomas & Betts includes fixtures designed for installation in all
hazardous location classifications: Class I Divisions 1 and 2, Groups
A, B, C and D; Class II Divisions 1 and 2, Groups E, F, and G; Class
III Divisions 1 and 2. Specifiers specialized in industrial lighting
are now assured that they can specify certified hazardous location
equipment also approved and compliant to NRCan/CSA C22.2 No.
141 standards. The new technology also significantly improves the
maintained light output of the LED by utilizing materials that operate
at lower temperatures than the previous generation of LEDs.
To validate the design: in-house LED life tests commenced early in
2009, one year ahead of the adoption of the pictogram exit sign by
the National Building Code. Data collected during 45,000 hours (five
years+) of continuous operation indicate that LED light depreciation
is less than 5% of the initial levels in 2009. This enables us to raise
our statistical prediction of our LED life to at least 90,000 hours (10
years) of continuous operation to the L70 level.
The outstanding test results with the InGaN-YAG technology and
patented LED drivers have allowed Thomas & Betts to manufacture
pictogram signs with maintained lighting performance. By design,
the initial luminance levels of the legend exceed by 50% to 100%
the minimum requirements of standard CSA C22.2 No.141-10. As
a consequence: even after 10 years of continuous use the projected
luminance levels of the pictogram legend will still be compliant with
the CSA standard of visibility.
First in the industry with proven long-life test results, Thomas & Betts
manufactures pictogram exit signs with ten years+ of CSA photometric
Following the requirements of the National Building Code, the new
generation of exit signs has replaced the text legend (EXIT, SORTIE)
with a pictogram legend featuring a green running silhouette on a
white illuminated background. As a consequence the legend is now
illuminated by white LEDs, which replace the traditional monochrome
red or green LEDs. Due to different manufacturing technologies
the utilization of white LED has raised awareness about their life
expectancy in continuous operation.
White LEDs are increasingly being used in the lighting industry. Their
operational life is defined by industry standards like LM80, as the time
elapsed until the LED luminous flux decreases to 70% of the initial
value (life definition: L70). Following the minimum requirements of
the LM80 standard, LED manufacturers usually test their products
for 6,000 hours (little longer than 8 months) and then predict the
total operational life based on statistical methods and extrapolation.
To insure the quality and long-life of pictogram signs the design and
engineering team of Thomas & Betts has carefully selected the LED
technology for their products. The LED chip is based on a compound
of three elements: Indium, Gallium and Nitrogen (InGaN) and
generates a mono-chrome light wave of royal-blue color. The white
light emission is obtained by covering the chip with a layer containing
mainly phosphor and three other elements: Yttrium, Aluminum and
Garnet silicate minerals (YAG). The InGaN-YAG technology has an
estimated operational life of minimum 50,000 hours before the light
output decreases to 70% of initial level.
Furthermore, the LEDs are powered by a T&B-patented electronic
circuit for constant direct current (CDC), specially designed to drive
the LEDs for an extended operational life.
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