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Single- or Three-Phase, Delta or Wye: Which Power Strip Is Best For Your Equipment Load?

February 02, 2009

Power requirements at the cabinet level are becoming more demanding from a standpoint of equipment density of a single cabinet and the power input requirements of this equipment. In the past, one (or two, if redundancy is to be considered) single-phase power strips would satisfy most power needs. With the advent of sophisticated network switching, blade server technology, built in power supply redundancy, and power supply real-time load sharing/balancing to mention a few advances, placement of single-phase power strips in many instances prove inadequate to meet the increasing equipment power demands. It’s like feeding a lion a squirrel for dinner – short term burst of energy, but no stamina. Not to mention the sheer quantity of single-phase power strips needed to satisfy power requirements may prohibit their positioning within a single cabinet.

CPI Power StripSingle-phase power strips still and will always hold a strong place within a data center, but matching the power strip to the equipment density and power requirements at the cabinet level is more critical. Enter the three-phase power strip. It may provide among other configurations varied outputs on the same strip (120/208 Volt outlets), more precise load balancing of equipment-to-phase on the same three-phase circuit, and a higher output wattage capacity which will allow more equipment to be connected to the same power strip – not multiple single-phase strips.

Three-phase power strips come in two configurations – Delta and Wye. In a Delta configuration, the circuit contains 4 wires (3 hot, 1 ground). All hots are the same voltage and because there is no neutral in the wiring, all outputs will be the same as the input voltage (240 Volt in/240 Volt out). A three-phase delta power strip has the same capacity as three individual single-phase power strips. In a WYE configuration, the circuit contains 5 wires (3 hots, 1 neutral, 1 ground). Because there is a neutral, it is possible to configure buss arrangement to produce either a low voltage (120 Volt) or a high voltage (208 Volt) output within a single power strip thus allowing for much greater flexibility in applications.

CPI offers three-phase power strips in both WYE and Delta configurations. Both provide several options that fit most data center needs. Some of these include:

  • 120/208 Volt WYE and 250 Volt Delta
  • 20 Amp, 30 Amp, 60 Amp, 80 Amp, 120 Amp
  • Vertical and Horizontal (19” EIA rack-mount)
  • NEMA and IEC inlets and outlets
  • Various outlet configurations (mix of outlets)
  • Optional local and IP Metering
  • Optional magnetic breakers

See CPI's complete line of power products at If  you have questions about which power strip is best for your equipment, leave a comment below or email You can also call 800-834-4969. Bob Sienkiewicz, Associate Product Manager.

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