 Nearly all 50 states rely on the National Electrical Code (NEC), published as a standard by the National Fire Protection Association (NFPA), as the code they use to regulate electrical installation in new construction and renovation projects. The NFPA recently published the 2005 version of the NEC, which is enforceable in all states and municipalities that adopt it. Several provisions in the new Code affect lighting, including lighting control panels, metal halide fixtures, and disconnecting fluorescent fixtures prior to servicing.The 2005 NEC went into effect January 1, 2005, but adoption can vary from state to state (and municipality to municipality). Based on the rate of adoption of the 2002 NEC, several states may adopt the Code right away, with about half the states adopting it in 2005. At the time of writing, according to the National Electrical Manufacturers Association (NEMA), several states, including Texas, North Carolina and New Hampshire, have adopted the 2005 NEC, with various timelines for enactment.
Protected Lamps in Metal Halide Fixtures
Metal halide (MH) lamps have the possibility of “non-passive failure” at end of life, which can cause hot quartz elements to exit the fixture.
The 2005 NEC addresses non-passive failure in Article 410.73(F)(5), “Metal Halide Lamp Containment,” which states: “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.”
This means that either an enclosed fixture can be specified (with any type of lamp, including Type-E and Type-S), or an open-optic fixture can be specified that only operates Type-O lamps. These open fixtures feature a socket that can only operate Type-O lamps.
Type-O lamps are protected lamps, typical for 175-1500W sizes, that have additional containment around the arc tube. They feature a special base (EX39) so that they can only operate in compatible special sockets.
Fixtures with thick-glass PAR MH lamps are exempt.
To an extent, the lighting industry has already been applying this rule to indoor open MH fixtures that operate lamps less than 350W. NEC is now applying it to all open MH fixtures. In the future, UL may review this requirement and if they adopt it as a standard for fixture manufacturers, the requirement will truly become national, since not all states may adopt the 2005 NEC quickly.
This requirement is not expected to significantly change specification practice. Specifiers will need to make sure that enclosed fixtures are suitably rated, and make sure open fixtures have a physical means so that they only operate Type-O protected lamps. In addition, they will have to make sure that they specify Type-O protected lamps. Overall, this Code requirement is expected to simplify the MH systems options that are available.
Metal Halide and Mercury Vapor Fixtures in Sports, Mixed-Use and All-Purpose Facilities
In these facilities, the lamp’s outer bulb can be broken during normal use of the space. When the bulb breaks, glass can fall out of the fixture into occupied space. In addition, the arc tube may continue operating, resulting in possible overexposure to UV radiation among occupants, which can cause sunburn and a burning sensation around the eyes.
The 2005 NEC addresses this situation in Article 410.4(E), which states: “Luminaires 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 shall be permitted to have an additional guard.”
NEC requires that these lamps be completely enclosed with a glass or plastic lens to protect the lamp from damage. The fixture can contain an additional guard such as an external screen or cage, but this is not a substitute for the required enclosure.
Disconnecting Means During Re-Ballasting
Industry data shows that a leading cause of fatalities among electricians is electrocution while working on 277V lighting systems. Some believe that this is partly because electricians are often pressured to change out ballasts while circuits are energized to avoid removing light from the area of servicing, causing them to ignore applicable warnings, instructions and training.
NEC has addressed this situation in Article 410.73(G), “Disconnecting Means,” which addresses changes to how fluorescent fixtures are disconnected prior to electrical work to prevent the possibility of shock hazard. This Article states: “In indoor locations, other than dwellings and associated accessory structures, fluorescent luminaires that utilize double-ended lamps and contain ballast(s) that can be serviced in place or re-ballasted must have a disconnecting means, to disconnect simultaneously all conductors of the ballast, including the grounded (neutral) conductor if any. The disconnecting means must be accessible to qualified persons.” There are a number of exceptions to this rule, which cover installations or conditions where rule variations are needed or it isn't practical to apply the rule, such as hazardous location fixtures and fluorescent exit signs.
This requirement, however, will not become effective until January 1, 2008, to allow manufacturers time to comply. Basically, it appears to be a 2008 NEC requirement.
Lighting Control Panels
Industrial control panels used to control such systems as lighting, conveyor systems and air conditioning are, in many cases, manufactured in the field. The individual devices used in the system may be listed, but not the resulting panel itself. This has been a troubling issue for both installers and inspectors, as increased use of the panels has been accompanied by increased misapplication.
Specifically, in the event of an overcurrent situation, the energy level may exceed the short circuit current rating (SCCR) on a component in the system.
First, it would be useful to define what constitutes an “industrial control panel,” since this term is not very commonly used in commercial applications.
NEC Article 409.2 states: “Definitions. Industrial Control Panel . An assembly of a systematic and standard arrangement of two or more components such as motor controllers, overload relays, fused disconnect switches, and circuit breakers and related control devices such as push-button stations, selector switches, timers, switches, control relays, and the like with associated wiring, terminal blocks, pilot lights, and similar components. The industrial control panel does not include the controlled equipment.”
“The key to this definition is that the panel contains two or more of devices as stated in the NEC definition,” says Scott Jordan, Marketing Manager for Square D/Schneider Electric. “As such, any enclosure containing a plurality of switching relays, an enclosure containing a relay and timer, or an enclosure containing a relay and a terminal block would fall under the definition as being classified as an industrial control panel.
“As such,” he adds, “virtually all lighting control panels, supplied either by a manufacturer as a complete assembly or custom built on a job site, will need to meet the requirements of NEC 409.”
The 2005 NEC addresses industrial control panels in a new section, Article 409, which is designed to facilitate safe installation as well as inspection. Previously, industrial control panels were installed based on general requirements from other NEC articles and special rules in some states. The new Article 409 covers general-use industrial control panels that operate at 600V or less. Article 409 impacts the way control panels are designed and built to ensure the entire panel and related components all meet a defined SCCR for the application, and that the panel is marked with the appropriate SCCR.
NEC Article 409.110 states: “An industrial control panel shall be marked with the following information that is plainly visible after installation: (3) short circuit rating of the industrial control panel based on one of the following: (a) short circuit current rating of a listed and labeled assembly; (b) short circuit current rating established using an approved method; FPN: UL 508A-2001 Supplement SB is an example of an approved method.”
The SCCR provision in UL 508A is also new and becomes a national standard in April 2006.
NEC also requires: “SCCR for a component or equipment shall be equal to or greater than the available short-circuit current where the equipment is being installed in the system.”
This NEC Article applies to OEMs, machine builders and panel builders, but it affects other professionals downstream as well. For example, if an existing panel is relocated, the state may require that 2005 NEC and its rules apply. If a panel is relocated after it is installed in compliance with 2005 NEC, the SCCR of the panel must be adequate for the new location. And inspectors will be looking for proper labeling on panels in new and updated installations.
For more information about the impact on lighting control panels, see new literature from Square D, including New Safety and Code Standards: Industrial Control Panels (PDF) and The North American Electrical Safety System: Changes Affecting Industrial Control Panels (PDF).
By Craig DiLouie
http://www.aboutlightingcontrols.org/education/papers/2005nec.shtml |
