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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 />a. Provision to padlock removable units in a partially withdrawn TEST position, with <br />the bus stabs disengaged. <br />044572017 <br />16480-2 <br />