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Plants Newport News Ship Building
 

Prismatic glass fixtures increase employee
safety/performance for ship builder


Newport News Ship Building (NNS) is the sole builder of nuclear-powered aircraft carriers in the United States and one of only two builders of nuclear-powered submarines. The company also constructs tankers, performs overhaul work and repair for military and commercial vessels, including cruise ships.

Often referred to as a city within a city, the Newport News, Virginia, facility occupies more than 550 acres and employs more than 18,000. Some of the buildings in the complex were constructed as early as 1890 and feature wooden construction with wood beam ceilings. Because of the age of the facilities, all were previously illuminated by incandescent lighting fixtures, with some DC units dating back to the 1930s and '40s.

In 1985, NNS launched a major lighting retrofit targeting 20 buildings ranging in size from 50,000 square feet up to 11 1/2 acres. According to Tom Chamberlain, supervisor, plant engineering, NNS, the retrofit was initiated for two major reasons: to assure that employees have enough illumination to safely perform their jobs, and to reduce energy consumption. Prior to the retrofit, illumination levels ranged from 5 to 25 footcandles on the work surface.

"In many instances, structures were lighted with bare incandescent lamps that tended to create a ball of light around the fixture, but left the rest of the ceiling dark. Illumination levels, in some cases, were adequate directly beneath the lamps, but insufficient elsewhere," Chamberlain said.

In preparation for the retrofit, NNS considered lighting systems from several manufacturers, conducting computer simulations of each to determine which system would provide the most light on the work surface with the fewest number of fixtures. Computer Aided Lighting Analysis (CALA) software from Holophane Corporation was used to determine fixture placement and estimate light levels.

Two different types of manufacturing facilities were retrofit: typical shop buildings and larger structures housing the steel production shops. During the early days of the retrofit, Holophane Prismpack® V fixtures with 400 watt high pressure sodium lamps were installed in the smaller buildings. Designed for low maintenance, the Prismpack V units features a non-deteriorating borosilicate glass reflector and sealed aluminum reflector cover.

Spacing ratio for the units was 1:1, with fixtures located 20 feet on center. Mounting height ranged from 20 to 25 feet. Following installation of the Prismpack V units, illumination levels increased to 80 footcandles on the work surface.

Later, NNS began utilizing Holophane Prismalume® units with prismatically controlled uplight (15 percent).

"In some instances, the ceiling is as high as 20 feet above the fixtures. Because of the uplight provided by the Prismalume fixtures, employees felt that they have more light, even though the illumination levels were the same. With the Prismalume fixtures, the atmosphere appears brighter and more comfortable," Chamberlain said.

The larger buildings were retrofit with Prismpack V units and 1,000 watt high pressure sodium lamps. Fixtures are mounted at 50', spaced 30' on center.

According to Chamberlain, the steel production shops tend to have a hazy, dusty environment because of welding particulates in the air. Beneath the incandescent system, light levels were so inadequate that the company experienced welding rejection problems because inspectors could not see well enough to examine the welds. Since the Prismpack units were installed, illumination levels have increased to 80 footcandles, and inspection problems have been eliminated.

"One of the goals of the retrofit was to prevent injuries before they happened. Not only have we accomplished this objective, but we've seen a big boost in morale because employees can see better to perform their jobs," Chamberlain said.

One of the project's challenges was to keep all shops in production during the retrofit. Therefore, all work was performed during the third shift. The Holophane fixtures include the quick disconnect feature to facilitate installation and maintenance.

Chamberlain indicated that NNS has no formal plan for maintenance, but will spot re-lamp as needed. All fixtures are controlled by circuit breakers.

Because of the company's concern for safety, the retrofit also included employee parking lots, which were previously lighted primarily with 1,000 watt mercury vapor units mounted on 35-foot steel poles. Ballasts were located on the bottom of the poles, with four lamps mounted on the top of each pole. Illumination levels measured only 1/2 to one footcandle.

"The manufacturing facility is located downtown and earlier we had some serious problems with crime," Chamberlain related. "Since the lighting system was retrofit, the incidence of crime has dropped dramatically."

NNS is constructing some new buildings and Chamberlain indicated Holophane lighting is being installed in those facilities, as well.


 

 
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