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2 .02 CONSTRUCTION <br /> A. Enclosure <br /> 1 . Enclosure type shall be NEMA Type 1 A unless otherwise approved by Owner ' s <br /> Representative . <br /> B . Structure <br /> 1 . Motor control centers shall consist of a series of metal enclosed , free -standing , dead front <br /> vertical sections bolted together to form double wall construction between sections . <br /> Individual vertical sections shall be nominally 90-in high, 20-in wide and 20 -in deep <br /> unless otherwise required . Bottom channel sills shall be mounted front and rear of the <br /> vertical sections extending the full width of each shipping split. Top of each section shall <br /> have removable plates with lifting angle. Make provisions for field installation of <br /> additional sections to each end and provide full depth cover plates (rodent barriers) at each <br /> end of the motor control center channel sills. <br /> 2 . Provide continuous top and bottom horizontal wireways extending the full width of the <br /> line-up , isolated from the horizontal bus. Provide a 4-in wide, full height, vertical wireway <br /> in each section, equipped with a hinged door and cable supports. Vertical wireway shall be <br /> isolated from the bus and device compartments. Wireways openings shall have rolled <br /> edges or protective grommets . <br /> 3 . Provide individual, flange formed, pan type door with concealed hinges and quarter turn <br /> latches for each device compartment and future space. Doors shall be removable. Door <br /> removal shall not be required to withdraw starter units or feeder tap devices . <br /> 4. Motor control centers shall be designed for against-the-wall or back-to-back mounting. All <br /> wiring, bus joints and other mechanical parts requiring tightening or other maintenance <br /> shall be accessible from the front or top . <br /> C . Unit Compartments <br /> 1 . Provide individual compartments for each removable combination starter and feeder tap <br /> device unit. Each vertical section shall accommodate a maximum of six compartments. <br /> Steel barriers shall isolate the top, bottom and sides of each compartment from adjacent <br /> units and wireways. Removable units shall connect to the vertical bus in each section with <br /> tin plated, self aligning, pressure type copper plug connectors. Size 5 and larger starter <br /> units may be wired directly to the bus. Removable units shall be aligned in the structure on <br /> guide rails or shelves and secured with a cam latch mechanism or racking screw. <br /> 2 . Provide individual, isolated compartments for all fixed mounted devices including circuit <br /> breakers, cable lugs, metering, relaying and control devices. Main and bus tie circuit <br /> breakers shall be wired directly to the main horizontal bus. All bus connections shall be <br /> fully rated. <br /> 3 . Provide the following features: <br /> I <br /> a. Provision to padlock removable units in a partially withdrawn TEST position, with <br /> the bus stabs disengaged. <br /> 044572017 <br /> 16480-2 <br />