Does the data center BMS/DCIM need its own dedicated UPS?

By: Barry Elliott, Director, Capitoline


Should a data centre Building Management System (BMS) or Data Centre Infrastructure Management (DCIM) be powered by the same system that it is monitoring? Most data centre BMS systems are powered by one of the Uninterruptible Power Supply (UPS) sets used for the Information and Communications Technology (ICT) equipment, so they are effectively powered by what they are monitoring.

TIA-942 Revision B, 2017 Telecommunications Infrastructure Standard for Data Centers, states “Security, Data Gathering Panels (Field Panels) UPS Capacity, Rating 3: Building UPS or local battery backup (8 hours min).”

One should consider if the best design solution is to have a separate UPS with an 8-hour battery for all BMS/DCIM monitoring and control system as well as security and fire detection systems.  The communications links to the outside world should also be relayed as far as possible through equipment that is separate from the data centre’s normal communication systems.

A Rating 4 system, where power and cooling systems may be duplicated, should have a separate BMS/DCIM capability each with its own UPS-backed power supply. A Rating 3 system with one BMS/DCIM should ideally have two UPS paths feeding it.

BMS/DCIM systems that are monitoring-only are inherently fail-safe as they have no ability to change anything, however a system that can be used to make operational changes or settings must be viewed and used with caution as it can become a single point of failure if it sends erroneous command signals to vital power or cooling equipment.

The considerations above are perhaps most appropriate for larger data centres. For small data centres it may be best to utilize a completely separate rack dedicated to the DCIM controller, the door access system, the Closed-Circuit TV (CCTV) controller and recorder and anything else of a monitoring/security nature. In the bottom of the rack it may be wise to put in a dedicated UPS with the largest battery that will fit. The UPS itself has a manual bypass that can be switched to raw mains or another UPS output to maintain the philosophy of concurrent maintenance for the DCIM and its UPS.

More details on data centre design to TIA-942 principles can be found at


The ideas and views expressed in this guest blog article are those of the author and not necessarily those of TIA or its members companies.