Determining Power Requirements for Access Control

March 2, 2012

Power to readers is often provided by the access control system. To ensure there is an adequate supply of clean and efficient power, an installer needs to calculate the total load for the installed access readers as well as their controller modules. Card readers, biometric readers, turnstiles, etc. all have differing power needs, and an access control system may not be able to provide. In this case, it is necessary to introduce additional external power sources.

If required, it is necessary to select one or multiple power supplies based on a few important criteria:

  • Type of power supplies for the system infrastructure (PoE or analog)
  • Operating voltage of the readers (AC or DC)
  • Total power requirement of the readers system-wide
  • Locations of the power supplies throughout the system
  • Number of power supply outputs needed to handle all the devices
  • What agency listings are required for compliance
  • If battery back-up is required specifically for the readers, and whether UPS back-up has been specified for the system
  • Cable thickness and length, as voltage drop is always an important consideration

Magnetic locks, strikes and request-to-exit devices also have specialized power requirements. The variety of access control power needs – for systems from one or two doors up to hundreds of doors – requires a variety of power solutions. Also, networked IP access control systems often use PoE midspan injectors like NetWay from Altronix which ensure adequate power delivery to networked IP system components.

For analog infrastructure, expandable power systems that are custom-configurable address the specialized needs of access control. For example, Maximal Access Controllers from Altronix provide distributed power and are expandable with the addition of field-installable UL listed sub-assemblies. This allows installers to customize units to provide Maximal power when and where they need it for their specific access control devices. The sub-assemblies include power distribution modules and access power controllers that allow for a selectable fire alarm disconnect and other features feature.

The bottom line is that power plays a crucial role in your system and should not be overlooked.