Technical Requirements -
Mechanical/Plumbing/Electrical
Electrical
Electrical systems shall be designed to comply with the current editions of the NEC
and NFPA. Contact VA if state and local codes are more stringent. Provide non-
coded general evacuation fire alarm system in 1/2" conduit complying with the
National Building Code and NFPA 72 and 100.
All wiring should be insulated copper conductors, installed in metal raceways except
as modified in this manual. Raised access floors, cellular floors or underfloor ducts
should be considered for office areas. Wiring for a security system shall be
incorporated into the electrical and cable plant designs in accordance with code
and VA specifications.
Standard, "house power" shall be provided to all areas of the building per standard
architectural/engineering practice and National Code with the additional VBA
requirements listed in this document. Additional power requirements are necessary
for non-linear switch mode power supplies found in
ADP equipment such as PCs printers, monitors, servers, et ceteras.
Non-linear ADP loads are best powered using Isolated power. Isolated power
consists of a PDU or power panel fed from a K-13 or higher isolation transformer.
This transformer should be a "step down" (480 - 208/120VAC) transformer to
minimize feeder size to the local distribution panel and can be located in the
electrical closet or PDU where branch circuits originate. The associated
PDU/distribution panel will feed orange Isolated ground receptacles for computer
loads in general office areas outside the computer room. This includes printers and
scanners not on UPS power. The power panel shall have a full capacity isolated
neutral bus and isolated ground bus.
All isolated circuits feeding ADP equipment shall be installed with oversized
neutrals to reduce neutral heating. Neutrals shall have current ratings of at least 1.7
X phase rating to achieve these results. A ground wire should be pulled for each
circuit along with a dedicated neutral (for each 3 phase feed). The transformers shall
be sized, installed, and protected per manufacturer's recommendations and Code
requirements and allowance will be designed in for 30% additional capacity.
PDU's/power distribution panels shall have a minimum of 30% spare, 3-pole
breaker positions with a proportional number of single, two phase and three phase
spare breakers.
Page 4-12
VBA Design Guide
Previous Page
