construction contract. If distribution is to be provided
If the UPS system is backed up by a generator to provide
under the building contract, it shall be designed according
for continuous operation, the generator shall provide
to the criteria in this section.
power to all necessary auxiliary equipment, i.e., the
lighting, ventilation, and air conditioning supplying the
Power Distribution Units (PDU's). PDU's with internal
UPS and the critical technical area.
or remote isolation transformers and output panelboards
shall be provided in all computer centers to reduce/
System Status and Control Panel. The UPS shall include
eliminate harmonic currents generated by non-linear
all instruments and controls for proper system operation.
loads and reflected back to the neutral service conductors.
The system status panel shall have an appropriate audio/
Neutral busses/conductors shall be sized at 200% of phase
visual alarm to alert operators of potential problems. It
busses/conductors. PDU's with internal or remote
shall include the following monitoring and alarm
functions: system on, system bypassed, system fault, out of
phase utility fault, closed generator circuit breaker. It shall
neutral size into account.
have an audible alarm and alarm silencer button. Since
UPS equipment rooms are usually unattended, an
Computer Center Grounding. To prevent electrical noise
additional remote system status panel must be provided
from affecting computer system operation, a low-
in the space served by the UPS. The alarms shall also be
frequency power system grounding and a high-frequency
transmitted to the BAS.
signal reference grounding system shall be provided. The
design of the technology/server room grounding system
UPS and Battery Room Requirements. Provide
shall be discussed with the computer center staff.
emergency lighting in both spaces. Provide a telephone in
or adjacent to the UPS room. Battery room design must
Low Frequency Power System Grounding. The primary
accommodate: proper ventilation, hydrogen detection,
concern is to provide a safe, low-frequency, single point
spill containment, and working clearances. See Chapter 3:
grounding system that complies with Article 250 of the
Architectural and Interior Design, Space Planning, Spaces
National Electrical Code. The single point ground must be
for Uninterruptible Power Systems (UPS) and Batteries for
established to ground the isolation transformer or its
additional requirements for UPS and battery room. Also,
associated main service distribution panel.
see NEC and Chapter 7: Fire Protection & Life Safety for
A grounding conductor shall be run from the PDU
isolation transformer to the nearest effective earth
Computer Center Power Distribution Unit
grounding electrode as defined in the NEC. All circuits
serving Automated Data Processing (ADP) equipment
In some GSA buildings the power distribution system for
from a PDU shall have grounding conductors equal in
computer centers will be designed by the tenant agency.
size to the phase conductors.
In that case, utility rough-in shall be provided under the
204 F A C I L I T I E S S T A N D A R D S
6.13 Clean Power Systems
Revised March 2005 PBS-P100