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Installation Guide
© 2018 HID Global Corporation All rights reserved.
Web-Based Access Control Solution
ACW2-XN
10
FAQ
Fail Safe versus Fail Secure
Electrically controlled locks fall in to one of two categories:
1.
Locks that require power to lock (with loss of power, these are unlocked, allowing EVERYBODY
access)
2.
Locks that require power to unlock (with loss of power, these are locked, allowing NOBODY
access)
The first is considered fail SAFE, as people can still escape the building, and help can get in, should some
misfortune occur.
The second is considered fail SECURE, as intruders cannot just walk in when power is lost.
Which lock to use
Mag locks are inherently Fail Safe, as they require power to lock.
Strike locks are available in Fail Safe as well as Fail Secure versions, but are most often Fail Secure.
CAUTION:
•
There is another level that should also be considered:
What relay terminals to use
The relays on the AW2 module should be switching power from an independent source, and so a similar
principle also applies to your choice of Normally Open (NO) or Normally Closed (NC) relay terminals:
Use the NC and COM terminals for switching circuits that you wish to keep energised should power to the
AW2 module be lost.
Use the NO and COM terminals for switching circuits that you wish to be cut off in the event that power
to the AW2 module is lost.
