Custom Enclosures Tackle Tight Quarters

A number of companies have begun offering large non-metallic junction boxes and enclosures that are a good fit for the humid, corrosive environments found in the water treatment industry.

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A number of companies have begun offering large non-metallic junction boxes and enclosures that are a good fit for the humid, corrosive environments found in the water treatment industry. One such company combines modern materials and cutting edge technology to fabricate custom and stock enclosures designed to protect electrical systems.

In one recent example, electrician Warren Weller of Rapid City, SD, faced a basement ceiling challenge in a water treatment control building. The motor control room was above the basement with a 12-inch-thick, poured concrete floor in between. Electrical service for the entire plant entered the control room through a series of conduit holes bored through the concrete floor. The challenge was to design a multi-function enclosure that could hang from the basement ceiling in this tight, damp environment.

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Staff at Rapid City assembled the modular enclosures on site.

The application called for the equivalent of a 48" wide by 108" long by 36" deep junction box with openings on the top that fit against the ceiling. These openings would accept the cables running through the bore holes from motor control center above. The goal was to offer access for pulling and connecting cable and terminating numerous conduits in an enclosure that was corrosion resistant and light enough to hang from the ceiling.

Weller envisioned an upside down box with large rectangular holes in the bottom and a flat lid sealed by a gasket against the box. But hanging an enclosure of that size in the water plant basement posed problems due to a congested work area, with the added difficulty of hanging it upside down.

Midwest Plastic Fabricators (MPF) was selected to provide a custom-designed enclosure. MPF uses CNC technology and PVC material to manufacture enclosures, cabinets, and boxes for conduit and control systems.

Trading design concepts and ideas with the Ohio-based manufacturer, Weller's solution was a design/build project consisting of three separate enclosures that would assemble on site. Recognizing easy installation as a priority, MPF assembled the components prior to shipment to insure fit. The unit was then disassembled and shipped by motor freight as three separate enclosures.

Staff at Rapid City were able to attach the components to the ceiling, then to each other. The ease of cutting conduit entrances in the PVC assembly when in place made the many conduit connections and cable pulling a relatively simple task.

In another recent project, the Immokolee Wastewater Treatment Plant east of Naples, FL, used 20" x 18" x 8" PVC junction boxes as a water tight liner in traffic-rated concrete handholes. The junction boxes provide access for wire pulling and connection for the underground conduit system to remote service equipment. The PVC boxes featured a gasketed shoebox-style lid attached with stainless steel fasteners.

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The ease of cutting conduit entrances in the PVC assembly helped simplify cable pulling and conduit connections.

The PVC material offers less resistance than metal for cutting holes for the stub ups for conduit entrance. In addition, as non-conductive material, PVC eliminates any potential shock hazard. The UL listed PVC material has a 94V-0 flame rating. The boxes have been tested to UL50 and NEMA 4X standards and are ETL Listed.

For more information on Midwest Plastic Fabricators and its products, visit www.midwestplasticfabricators.com.

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