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Fail Safe vs. Fail Secure

Erik Sherman
Erik Sherman
business.com Contributing Writer
Updated Apr 01, 2022

Fail-safe and fail-secure locks are critical access control tools that protect your business and the people within. Learn how they work and which system is best for your company.

Fail safe and fail secure are terms that refer to access control systems. These aren’t computer systems, networks or data, but rather physical entry to buildings. Physical security is critical to your business, but it’s often discounted as obvious when compared to the complexity of digital security. Lock the doors, have someone at the front, use smart cards or other electronic methods to enter sensitive areas – what else is there to know?

Quite a bit. The simplest security can be the slipperiest. For example, an empty pizza box can let a crook walk virtually unchallenged into many buildings. Access control is critical. 

Editor’s note: Looking for the right access control system for your business? Fill out the below questionnaire to have our vendor partners contact you about your needs.

What is a fail-safe system?

A fail-safe system is designed to default to an unlocked door. When power is applied to the door, the locking mechanism engages. When the power is off, the lock disengages and the door is open. The devices employees use to gain entry cause power to be shut off to the lock, allowing the door to open. 

A fail-safe lock is a safety measure. The most common applications are for doors that someone must always be able to enter. That includes fire doors and doors in stairwells. In case of a fire, people must enter and leave stairs freely or exit fire doors to move toward safety. One-way access is not sufficient. Because fail-safe doors can always be opened from the inside, there is no need to make special provisions for someone exiting.

However, fail-safe locks have weaknesses. Once the power is out, a locked door is no longer a barrier. Using a fail-safe door as an entrance from the exterior of a building isn’t wise because it would allow anyone entry. 

TipTip: If you need an access control system, check out our recommendations of the best access control systems available, and then evaluate them according to your business’s needs.

What is a fail-secure system?

Just as the name implies, the term “fail safe” indicates a lock’s mechanism. This is also true of fail-secure doors. 

A fail-secure door is locked when the power is off to the lock; apply power, and the lock opens. To open the door, an employee’s card, fob or other identity management solution causes the door to apply power to the lock.

If the power goes off, fail-secure locks all remain locked. The only way through from the outside is with a key. However, anyone can exit from the inside.

Fail-secure locks have different applications than fail-safe systems. The idea is that no one can be harmed if they can’t get through the door from the outside to the inside. If there’s danger on the inside, anyone can open the door without an access device. 

Fail-secure locks could prove dangerous in interior areas – like stairwells or fire doors – if there were an emergency.  However, such locks are suitable for doors that either lead to secure areas within your company or on exterior doors. Again, people on the inside can leave, but people on the outside can’t enter. 

TipTip: If there’s an emergency and the power goes out, use a fail-safe lock if a locked door would endanger lives. If an unlocked door puts your business at risk, use a fail-secure lock.

Which is best for your business?

Is a fail-safe lock or a fail-secure lock best for your business? This is a tricky question because it may well be that no single lock type is enough for your organization. 

Any building will have doors you can access from outside. During a power failure, you don’t want just anyone to be able to walk in at will to steal, cause damage or potentially endanger employees. Additionally, there may be secure areas within the building that only select people should enter. In these cases, a fail-secure lock would be necessary.

However, for public safety, other areas will need fail-safe locks. Fail-safe locks are crucial when people are exiting during an emergency, as stairwells and fire doors are critical tools for containing danger while allowing people to move away safely.

Deciding whether to implement fail-safe or fail-secure electric locks is a matter of strategic planning – considering both security and safety concerns. The right approach for your business will likely involve both types. 

Bottom LineBottom line: Fail-safe locks unlock on the access side when power is cut off, while fail-secure locks unlock on the access side when power is applied. Fail-secure locks are useful for front-entry doors, while fail-safe doors are vital for stairwell exits, fire doors and sensitive areas. You may benefit from a combination of fail-safe and fail-secure locks.

Safeguarding doors

The reason you need a fail-safe or daily-secure system is because a fundamental aspect of access control is safeguarding doors to prevent people from entering areas without permission. At the same time, those who need access must have a way to unlock a door.

With purely mechanical locks, regulating a door could become a nightmare of providing keys to those who need them, preventing unauthorized key duplication and regaining possession of keys when someone leaves the organization. Such key management would be prohibitively expensive, inefficient, risky and cumbersome.

FYIFYI: Safeguarding doors helps ensure that those who don’t work for your organization can’t just waltz right in. A proper visitor management system is essential to your workplace’s security.

Electromagnetic locks

One option from a key-based door is to an electromagnetic lock, in which a powerful electromagnet holds fast to a metal strip. This system prevents someone from opening a door while the power is on. 

These systems have an inherent weakness: If the power goes off the door is unlocked, and anyone can get through. 

This type of lock failure is an extreme security danger if it occurs with an external door, but it’s also questionable if used on internal doors if they’re meant to allow access only to certain people.

Smart security systems

A better choice for your company may be a smart security system, which uses electric lock mechanisms that allows for more flexible and convenient access control. 

A smart security system is based on a mechanical lock that comprises these three parts:

  • A handle or release mechanism someone uses to open the door physically
  • A latch, or the small bolt that slides out to lock the door
  • A strike plate, also called the strike, which receives the latch to keep the door locked

In an electric lock, the strike contains an additional electron component that allows for an electrical current to unlock the door, granting someone entry. The result is a full-featured physical security system.

This type of system still has keys for limited personnel who need to maintain access under all conditions. All other employees use some form of electronic identification for the access control system – including an identification card or key fob, keypad requiring a combination entry, release button at a reception desk or biometrics.

The IDs provide personnel with predetermined authorization levels based on their role in the company. Managers can change employee access by reprogramming the ID and modifying the security system’s settings. This setup is more secure than a purely key-based system or one that doesn’t provide locked doors.

There is one problem, however. As with an electromagnetic lock, if the power goes out, electric access devices no longer work. 

Image Credit:

RossHelen / Getty Images

Erik Sherman
Erik Sherman
business.com Contributing Writer
Erik Sherman is an independent journalist who has written thousands of articles about business, technology, security, finance, marketing, management, leadership, and small business. His is also the author or co-author of ten books. Before his career in journalism, Erik was in corporate management at a publicly-held company and ran his own businesses.