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The 2005 update
to the National Electrical Code (NEC) includes two changes that
affect the manufacture and installation of metal halide luminaires.
Both changes address methods for reducing risk when metal halide
lamps are used.
The purpose
of these changes is to reduce the risk of possible injury or property
damage. Metal halide lamps can sometimes explode, shooting hot glass
out of the luminaire. In an open luminaire - one that does not have
a lens - this can result in a fire, personal injury, or property
damage. Although violent failure is a rare occurrence (about three
incidents per year), the NEC has included these changes to help
reduce these hazards.
In sports facilities,
particularly in schools, athletic activity can break the outer jacket
of a metal halide lamp used in any luminaire. When this happens,
the arc tube can continue to operate with a damaged or missing outer
jacket. If this condition occurs in an open luminaire, it can lead
to UV overexposure, including sunburn and a burning sensation in
the eyes. The NEC change requires complete lamp enclosure in these
facilities, which will not only provide mechanical protection to
reduce the possibility of damage to the outer lamp jacket, but also
prevent the escape of harmful UV radiation and broken glass.
NEC changes
for open luminaires
The
NEC change regarding open luminaires is detailed in the new section
410.73(F)(5) titled, "Metal Halide Lamp Containment". It states
that, "Luminaires (fixtures) that use a metal halide lamp other
than a thick-glass parabolic reflector lamp (PAR) shall be provided
with a containment barrier that encloses the lamp, or shall be provided
with a physical means that only allows the use of a lamp that is
Type-O." (See ANSI Standard C78.389, listed in Resources, for more
information on lamp types.)
Therefore, to
meet the 2005 NEC requirements, luminaires that use metal halide
lamps must either:
• Be enclosed with a containment barrier, or
• Use a special, exclusionary lampholder (socket) that will
only accept an ANSI Type-O metal halide lamp.
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ANSI currently
classifies metal halide lamps with three possible ratings: Types
- O, S, and E. Type-O lamps include a shroud around the arc tube,
which helps prevent damage to the outer bulb in the event of an
arc tube rupture. In the ANSI C78.389 test, arc tubes are forcibly
ruptured to test the integrity of the bulb and to determine if the
design can be containment-rated. In order to receive the "O" rating,
the outer bulb cannot be cracked or broken in such a way as to eject
particles of glass when the arc tube is ruptured. Type-S lamps do
not include internal protection against failure, but previously
had been permitted for use in open luminaires when operated and
installed in strict adherence to manufacturers and NEMA guidelines
(see NEMA white paper, LSD 25). Type-E lamps are rated only for
use in enclosed luminaires.
By specifying
that only ANSI Type-O lamps are permitted in open luminaires for
NEC-compliant installations, the NFPA attempts to further reduce
personal and property damage from metal halide lamp failure. Types
lamps will not be permitted in open luminaires, and the specification
that open luminaires are manufactured with lampholders that only
accept Type-O lamps will help prevent accidental use of Types or
Type-E lamps during normal maintenance. Lamp
manufacturers that offer Type-O lamps, such as Venture Lighting,
are already equipped to test lamps and currently perform the forced
rupture tests and maintain the manufacturing processes necessary
to ensure suitable performance in the field. Because of lamp size
and shape restrictions, PAR lamps (parabolic aluminized reflector
lamps) cannot be used with exclusionary lampholders. However, if
they pass the ANSI containment test, they can receive the O rating.
Existing installations
that use open luminaires and Types lamps will continue to exist,
even in municipalities that adopt the 2005 NEC. Venture Lighting
strongly recommends that these lamps be replaced only with Type-O
lamps which directly retrofit all existing lampholders. To avoid
accidentally installing Types lamps, it is recommended that existing
mogul lampholders (type E39) be replaced as soon as possible with
exclusionary lampholders (type EX39). It
is expected over time that the mix of metal halide lamps available
will naturally shift to reflect the requirements of the 2005 NEC
and that there will be an associated shift to luminaires that are
either enclosed or that only accept Type-O lamps.
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NEC 2005
changes for sporting facilities
The NEC change regarding open luminaires is the new section 410.4(E)
that states, "Luminaires (fixtures) subject to physical damage,
using a mercury vapor or metal halide lamp, installed in playing
and spectator seating areas of indoor sports, mixed-use, or all-purpose
facilities shall be of the type that protects the lamp with a glass
or plastic lens. Such luminaires (fixtures) shall be permitted to
have an additional guard."
To address this
requirement, new installations or remodels must use enclosed luminaires
in facilities where there is a possibility of objects striking the
luminaire.
How is Venture
Lighting addressing the new NEC requirements?
Venture Lighting fully supports the NEC changes. These changes simplify
the metal halide systems options available and also reduce the potential
risks associated with failure to properly follow the warnings and
instructions for systems that specify open luminaires with Types
lamps.
All MP and MPI
lamps produced by Venture Lighting meet the requirements to be rated
Type-O, and can be used with confidence to meet the new requirements
of the NEC. Venture Lighting provides the industry's widest selection
of lamps that meet or exceed ANSI C78.389-2004 testing requirements
for a Type-O rating.
Resources
National Fire Protection Association (publisher of the National
Electric Code): www.nfpa.org. Also publishes:
• "Recommendations for the Care and Maintenance of High Intensity
Metal Halide and Mercury Lighting in Schools."
• LSD 31-2004, "A Lighting Systems Division Information Bulletin:
Changes to the 2005 NEC Will Impact Future Metal Halide Systems
Options."
• LSD 25- 2004, "Best Practices for Metal Halide Lighting Systems,
Plus Questions and Answers about Lamp Ruptures in Metal Halide Lighting
Systems."
American National
Standards Institute (ANSI): www.ansi.org. Publishes:
• ANSI C78.380, Annex B, American National Standard for Electric
Lamps-High Intensity Discharge Lamps, Methods of Designation.
• ANSI C78.387, American National Standard for Electric Lamps-Metal
Halide Lamps, Methods of Measuring Characteristics.
Underwriters
Laboratories. See "UL 1572, High Intensity Discharge Lighting Fixtures,"
Underwriters Laboratories Inc., Northbrook, IL. CSA C22.2 No. 9.0,
Luminaires, CSA International, Toronto, Canada. UL 1598, Luminaires,
Underwriters Laboratories Inc., Northbrook, IL. CSA C22.2 No. 250.0-00,
Luminaires, CSA International, Toronto, Canada. Note that these
last two standards are the Bi-national Luminaire Safety Standard.
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About the
National Electrical Code
The NEC is administered by the National Fire Protection Association
(NFPA) and is revised every three years. The 2005 NEC has been released
for publication and is currently available from the NFPA at www.nfpa.org.
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