Kentucky, USA
The Customer
The National Park Service manages nearly 400 sites throughout the U.S. and its territories including national parks, monuments, battlefields, historic sites and recreation areas. At Mammoth Cave National Park in Kentucky, the National Park Service manages, protects and runs tours in the longest cave in the world. This geological wonder, the 26th park to enter the National Park System, contains more than 52,000 acres and 367 miles of mapped underground passages.
The Challenge
The cave housed a lighting system that evolved piecemeal over about 35 years and created a number of problematic conditions. First, the system used bright lights, which promoted algae growth that was detrimental to the environment. This was compounded by the harmful effects of the bleaching required to remove the algae. Second, the 7200-volt system that ran directly under the tourist trail system posed a safety hazard.
By the spring of 2004, the Park Service was looking for a lighting system that would have minimal impact on the cave while being compatible with the practical and safety needs of the hundreds of thousands who visit the cave each year. In addition to illuminating the pathways with ample light for safe walking, the Park Service was hoping to use lighting to show off the various features and formations of the cave.
The challenges of putting in a new lighting system in this primitive and ecologically sensitive environment were enormous. Everyone had to abide by strict specifications and procedures and all equipment had to be hand carried throughout miles of cave chambers and passages. In addition, the installation had to be carefully coordinated to minimize the impact on ongoing tours.
The Solution
This unique application required a sophisticated system to achieve all its goals. The choices of fixtures and lamps were very precise. In some areas, to reduce damage to the cave and its artifacts, lighting had to stay within the 592nm color light spectrum. In addition to fluorescent fixtures, many LED lights with a mix of amber and white diodes were used to create light that emits a pleasing glow while minimizing environmental damage.
“When we started, we weren’t thinking about lighting controls at all,” noted Steve Kovar, Facilities Manager of Mammoth Cave. “It was our lighting consultant who brought up the issue and the system developed as the job moved forward.” The system consists of about 30 total, Z-MAX™ 48-, 24- and 8-channel relay cabinets with Ethernet cards; a Leviton NPC protocol converter; and network switch with fiber optic transceivers. Specially designed switching and networking assemblies housed in custom-painted stainless-steel waterproof enclosures feature internal heaters to cope with the 100-percent humidity. Power centers are supported by a fiber-optic control network distributed via five satellite racks located in the cave and on the surface.
Tour guides use pushbutton stations at the beginning and end of each tour segment to minimize the amount of time the lights are on— saving taxpayer dollars and national resources. These stations were custom built and painted to withstand the harsh conditions and to blend into the natural surroundings. A built-in phone system enables aboveground personnel to contact those in the cave, and vice versa. For example, tour guides can notify park staff to line up medical assistance if a visitor experiences a health issue while below ground.
The Results
Although improved lighting controls may not have been the primary goal of this project from the onset, the benefits have been substantial.
The system is equipped with electrical-current monitors and if the electrical flow through a relay varies from a predetermined level, that’s an indication that something is wrong (usually a lamp outage). Aboveground operators can fully monitor and control the system through graphic panels with custom displays that depict the cave network and indicate light status. The practical implications of this are huge. Facilities Manager Steve Kovar remembers when his electricians would carry heavy loads up to two miles into the cave only to discover that they had the wrong parts. “We had over 30 different types of lights and it seemed like we’d invariably go down there on the first attempt at repair with the wrong lights.” Now his staff comes in each morning and checks the computer. If there’s a problem, like a blown breaker, they know the exact circuit and can go out first thing to fix it—before any tours start. Kovar notes “When we started we had no clue we’d end up having a graphical user interface in here. Now I don’t think we can live without it!”
The new lighting system is also significantly more energy efficient than the ad-hoc system it replaced. Not only do the lights themselves draw less electricity, the convenient mechanism for switching lights off once a tour leaves an area, along with the constant monitoring afforded by a central control system, adds up to a system that is cheaper to operate. Central monitoring combined with built-in communication features also provides an extra measure of security and safety as it enables park staff to more closely track the movements of ongoing tours—and note any unexpected activity.
For More Information
To learn more about the wide range of Leviton’s lighting control and energy management solutions, please visit www.leviton.com/lms or call 503-404-5555.
To learn more about Mammoth Cave National Park, visit www.nps.gov/maca.