The two possible modes that lock use when they fail are fail-safe and fail-secure. It depends on the condition when to use a particular from of lock. Fail safe locks are able to unlock themselves when power is removed whereas fail secure locks are locked automatically when power is removed. Fail safe locks are deployed on doors which require re-entry and on areas which requires free access in emergency or fire related situations. Fail secure products are being utilized widely as compared to fail safe especially concerning the security related aspects.