Best Practices Data Center Electrical

      The purpose of this article is to provide a basis of "Best Practices Data Center Electrical" for data center management and infrastructure. Local business reasons, local governmental code or other circumstances may mitigate the implementation of Data Center Electrical.
       It should be understood that the implementation of best practices Data Center Electrical may require long term processes to be implemented, capital or expense funding and that the corrective actions will be ongoing.

• Two electricians should be required for all “hot” electrical work.
• Infrared inspections of all PDU/CPCs should be performed yearly. Circuits that indicate readings 10 – 20% more than the norm should be noted and investigated.
• Unused circuits should be turned off at the PDU/CPCs.
• All PDU/CPCs should have a ground strap connected to the raised floor or ground.
  •Harmonic distortion, both voltage and current, measurements should be performed yearly or when substantial amounts of new equipment are installed; or major changes in the data center occur.
• The signal reference grid should be checked for integrity and measured ground resistance on a yearly basis.
• The proper labeling of PDU/CPC circuit breakers and circuits should be checked on a yearly basis. Panel schedules should be updated immediately when circuits are added or de-installed
• Loads on PDU/CPCs should be evenly distributed across the phases in order to reduce harmonics.
• An independent ground wire, should be run with each circuit. Circuits should never share ground wires.
• An independent neutral wire should be run with each circuit. Circuits should never share neutrals. The sizing of the neutral conductor depends on the load and the harmonics present.
• Watertight receptacles should be used beneath the sub-floor if chilled water air handlers are installed in the space.
• Use of 'pin and sleeve' receptacles should be used. If not available, or used, twist-lock receptacles should be raised off the floor by approximately 1 5/8".
• Branch circuits should be designed with the following factors: 1200 VA on 15 Amp, 120 Volt circuits; 1800 VA on 20 Amp, 120 Volt circuits and 3600 VA on 30 Amp, 120 Volt circuits. The minimum conduit size should be 1/2". Individual neutral and ground conductor in each computer receptacle branch circuit with a 3% maximum voltage drop at the furthest outlet in branch circuits and a 5% maximum voltage drop from the main power source to the load.
• The grounding scheme design should provide equal ground potential for all metal supports, equipment enclosures, racks, raceways and raised floor.
• The IEEE Emerald Book should be the standard for grounding all facilities (signal reference grid).
• Unused Seal-Tight circuits should be removed from the sub-floor. This is NFPA code requirement; and, it helps to insure PDU/CPC panel schedules are kept current. Additionally, unused circuits impede proper airflow.
• When using standard 110VAC NEMA 5 plugs, tie wrap the plugs to the receptacles to insure that the plugs do not come loose. Some locations may choose not to allow these circuits under the floor in order to prevent unauthorized personnel from utilizing those circuits.
• All circuit breakers should be marked with a color coded schema to indicate whether they are normally open or closed. This includes PDU/CPC mains and branch circuits.
• Manual EPO switches should be setup as a multiple step device and protected with a cover. If the cover is lifted, an alarm is sounded indicating imminent activation. The EPO switch should have a back-lit and a printed warning attached. The location and layout of the EPO switches should be consistent for each location in order to reduce confusion. Note, check with the manufacturer of the EPO system and relevant UL & NRTL code before any modifications to the EPO system.
• UPS power in the data center will only be used for computer and communications equipment. At no time will the UPS power be used for test, construction, personal and janitorial equipment
• At no time will a IT workforce member operate a PDU or main circuit breaker without consulting office management personnel.