Medium Voltage Powerhouse

Specification

This document specifies the requirements for a factory-built, single-piece, NEMA 3R rated Medium Voltage (MV) Powerhouse. The powerhouse is designed to house MV and LV electrical distribution equipment and is intended for general-purpose, non-hazardous industrial applications. It must be capable of transport with all internal equipment installed.

• Enclosure Configuration: NEMA 3R rated, interlocking pre-galvanized steel panels, single-piece factory-assembled unit. Dimensions: 38 ft (L) x 15 ft (W) x 10 ft 6 in (Ceiling Height). Environmental design includes snow load (20 psf), wind load (130 mph, Exposure C), Seismic Category C, and interior lighting (30 foot-candles).

• Insulation Values: Walls (R-13), Roof (R-19), Floor (R-12), Personnel doors (R-6.8).

• HVAC System: Two (2) 4-ton, 480V, 3-phase HVAC units with temperature set points between 65°F and 80°F. Features include high/low pressure protection, low ambient control, and alarm relay.

• Structural Construction: Steel members (W16x26, C10x15.3), 1/4 in steel plate flooring with spray polyurethane foam insulation, 16-gauge galvanized steel panels for walls, roof, and ceiling. Includes wind-rated doors and exterior canopies.

• Finish Systems: Exterior ANSI-70 polyurethane, interior white polyurethane or pre-painted galvannealed panels, high-solids epoxy floor coating.

• Electrical Systems: All equipment UL listed, wiring per NEC voltage separation. Includes 120V duplex receptacles, GFCI, combination switch/receptacle stations, a 45 kVA transformer, 480/277V, 600A AC panelboard, and a DC PowerCab system. MV cable systems use 5 kV EPR/PVC shielded cables with cable trays. Grounding system includes copper bar loop and ground pads.

• Customer-Supplied Equipment (Installed by Contractor): Includes 5 kV switchgear, 5 kV MCCs, breaker lift truck, mechanical bus splicing, control wiring re-terminations, floor fastening, and heater/control-power circuits.

• Control Wiring: Up to 150 points for panel-to-panel control wiring (14 AWG THHN).

• Accessories: Includes "Danger High Voltage" signage, gutter system, removable floor cutouts, and a fire extinguisher.

• Documentation & Services: Requires PE-sealed structural calculations, HVAC calculations, center-of-gravity documentation, foundation load chart, UL compliance certification, customer FAT participation, electronic drawing sets, and project management services.

• Shipping Dimensions: Approx. 38 ft 6 in (L) x 15 ft 6 in (W) x 13 ft 2.5 in (H).

• Weight: Total approx. 66,301 lb (Empty: 42,996 lb, Installed Equipment: 23,305 lb).

Not applicable for this specification document.

Not applicable for this specification document.

• All lifting must use provided lift lugs.
• Spreader bars, rigging, and lifting gear are not included unless specified.
• HVAC units may ship loose.
• Temperature settings for independent HVAC units should be staggered by 5-10 degrees.

Form / Attachment / Pricing Sheet

This document is a plan layout for the MV-SG Power House, detailing the electrical power infrastructure for the Liquid Nitrogen Air Separation Unit at the John C. Stennis Space Center. It provides a visual representation of equipment placement and dimensions.

• Equipment Layout: Shows the placement of Medium Voltage (MV) Switch Gear, MV Transformers, Soft Starters, and various electrical panels (277/480V, 120/208V, DC).
• Dimensions: Provides approximate overall dimensions of the power house (38' L x 15' W x 10.5' H) and specific equipment dimensions.
• Notes: Includes critical information such as wind load, temperature range, heat loads, lighting specifications, DC voltage, transformer details, panel ratings, cable tray size, grounding, communication protocols (Modbus TCP/IP), and listing information (UL 1598).
• Sourcing Requirements: Notes that construction materials must follow domestic sourcing laws (Buy America, BAA, TAA).

This layout is crucial for bidders to understand the physical space requirements, equipment specifications, and installation considerations for the power house. It informs potential contractors about the scale of the project, the types of electrical components involved, and any specific compliance or sourcing requirements that may impact their proposal and execution plan.

Statement of Work (SOW) / Performance Work Statement (PWS)

This SOW outlines the requirements for the procurement, design, construction, equipment delivery, performance, testing, and documentation of a Medium Voltage (MV) Powerhouse. This powerhouse will support the Liquid Nitrogen Air Separation Unit (LNASU) electrical infrastructure at NASA Stennis Space Center.

• Procurement, design, construction, delivery, performance, and testing of a transportable steel MV Powerhouse.

• The powerhouse will provide electrical distribution, control, HVAC, grounding, and lighting systems.

• Equipment layout and dimensions are to conform to the "MV Powerhouse – Plan Layout" drawing (EMI XL50-26007-01, E-103).

• Specific materials, construction methods, and insulation requirements are detailed, referencing nVent RuggedSpec Equipment Center Specification.

• Adherence to codes and standards including NEC (NFPA 70), UL 508A, UL 1598, and International Building Code criteria is required.

• The powerhouse is to have a 10-year design life and be UL/cUL listed.

• Fire resistance with a flame spread rating of 25 or less.

• Structural materials must comply with Buy America, BABA, BAA, or TAA requirements.

• All electrical equipment must be UL listed.

• Testing includes Megger testing of nVent-furnished circuits and customer inspection/FAT.

• Delivery receipt of the powerhouse is to be complete by 4/16/27.

• Assembly details are to be provided at Stennis Space Center, Mississippi.

• The structure shall be NEMA 3R, built from 16-gauge interlocking galvanized steel panels.

• Insulation requirements for floor (R-12.0), walls (R-13), and roof (R-19) are specified.

• Specific door types (wind-rated CECO personnel doors) and paint systems are detailed.

• Major electrical equipment includes MV Soft Starters (provided by others), LV Dry-type Transformer, MVA Switchgear (5 kV), LV Panels, and battery racks.

• HVAC system includes two 4-ton exterior wall-mounted air conditioners.

• Communication interface: Modbus TCP/IP.

• Safety and labeling requirements include "DANGER HIGH VOLTAGE / KEEP OUT" signage and fire extinguishers.

• Deliverables include structural calculations, electrical drawings, HVAC calculations, BOM, manufacturer data sheets, and certification of structural integrity.