Prerequisites
Each company and perhaps even different doors within the company will have different requirements for access control, but there are some general principles to consider in every case. Before we can discuss them, however, we need to do a bit of homework.
Types of Electric Locks
For an access control panel to actually do anything useful, it needs to control some sort of electric lock. There are thousands of different models of electronic locks, but they can be divided into three main classes:
Electromechanical Locks
These are installed in the door itself and replace the normal handle/latch/deadbolt that a non-electric door would have. They can typically be unlocked both by manually turning the inside handle or by applying electricity.
Electromagnetic Locks
Often used to secure glass doors, these locks hold the door shut by powerful magnets. Because of this, however, there is no way to grant mechanical egress as long as the lock is powered - something has to turn it off for the door to open.
Electric Strikes
Electric strikes aren't Installed in the door itself but in the doorframe where the strike plate would normally go. They capture the latch of the door to prevent its opening normally, and when activated the side of the strike opens and allows the door latch to leave.
When you open a non-electric door you do so by turning a handle and retracting the latch, but an electric strike allows the door to open without being the latch retracted at all.
This has the advantage of often not requiring any modification to the door - you just have to modify the doorframe instead.
Fail Safe vs Fail Secure
These two terms describe what happens to an electronic lock when it loses power - does it remain locked or become unlocked?
A Fail Safe lock is safe for the users inside the building because it unlocks and allows them to exit when the lock loses power (think an emergency situation like a fire or earthquake). This means that the lock needs power constantly to stay locked.
A Fail Secure lock remains locked even with no power, keeping the building secure.
Watchmark access panels have a switch on the back that allows you to select your lock type. Normally Open (NO)
mode is used for Fail Secure locks (since the power circuit is normally an open loop - meaning there's a disconnect in the circuit and so power can not normally flow). Normally Closed (NC) mode is used for Fail Safe locks, since the power circuit is normally a closed loop (meaning power is flowing through it normally).
So when a user scans their badge and unlocks the door, a Fail Safe/Normally Closed lock will have it power cut off for a few seconds by the access panel, whereas a Fail Secure/Normally Open lock will be given power for a few seconds by the access panel.
Some types of electronic locks are by their nature either fail safe or fail secure: the magnetic locks commonly installed over glass doors, for example, must have constant power in order to hold the door closed and so are all fail safe. But the common electric strikes that install into the door frame can be either fail safe or fail secure (some are even configurable).
Challenges
Now that we know what those terms mean, let's consider good access control design. There are three major challenges to consider here:
Safe egress
Keeping your users safe in case of fire or other emergency by allowing them to exit the secure space requires careful planning. If you're using a Fail Safe lock, any emergency that causes power loss to the access control panel will unlock the door - but what if you've plugged the Power-Over-Ethernet router that's supplying power to your access panels into a UPC battery backup? In that case the unit might not lose power even during an emergency and you'd need to be very sure that the request-to-exit sensors were still operational.
Some request-to-exit sensors are just simple buttons wired into the access panel and don't require power at all - as long as the access panel itself has power they'll work just fine. But other request-to-exit devices are motion sensors usually installed above the door on the secure side and unlock it when they detect someone approaching. This latter kind will definitely require power.
Example: You have a fail safe lock that depends on a request-to-exit motion sensor installed over the door to allow egress. One day your building loses power due to an earthquake. The access control panel stays powered thanks to a battery backup BUT your motion sensor isn't wired into the battery backup and loses power. Now users have no way to exit the building and you have a serious problem.
Fail-secure locks have a more obvious challenge - if your access panel loses power then your door stays locked, which means users cannot exit the secure space if they are normally dependent on any sort of request-to-exit sensor (either powered or unpowered).
Security
In addition to considering how your users can safely exit the secure space in case of emergency, you also have to consider how to keep your secure space actually secure in emergencies.
In almost all cases, if you choose a fail safe lock, you'll also need to choose a backup power supply capable of keeping those locks (and any associated request-to-exit sensors which require power) online for at least several hours in case of power failure.
Example: You have an electromagnetic lock holding a glass door closed and your building loses power in the middle of the night. You don't have a battery backup, so that door is now unlocked, which is probably not what you want.
Fail-secure locks are a clear win here, since if the access panel loses power the lock will stay locked.
Legal
A wide range of building codes and other legal requirements will apply to you depending on your location and also your area of business (retirement homes and prisons, for example, have especially strict requirements).
Doors in certain locations may have more stringent safe egress requirements than the other doors in your building - for example, a door leading from a stairwell onto a rooftop may be required by code to be fail safe. However, electric strikes on fire-rated doors are pretty much always required to be fail secure.
Please be sure to research all applicable legal requirements before making any decisions - or better yet, hire a knowledgable contractor who's familiar with them to help you.
Our Recommendation
It's impossible to apply the same solution to every scenario - so please understand that our recommendation is not universal and might well be illegal in your particular situation! That said, here's our idea of the best fit for most cases:
Normal doors
Fail secure locks with egress based on mechanical devices and not on electronics. Most electromechanical locks have this built in (users on the secure side of the door can open it just by turning the handle), and for electric strike locks this means making sure there's a paddle or handle on the secure side of the door that can retract the latch (so even when the electric strike refuses to allow the latch to pass out extended, the latch can be retracted and the door will open anyway).
Doors required to be fail safe
Select your choice of fail safe lock type and then add a good battery backup system. For user convenience you'll want to install a motion sensor request-to-exit device, and code will almost certainly require that you also adding a lighted request-to-exit button on the same circuit, so even in the event of failure/power loss on the motion sensor, users can still press the button to exit.
Reach out
Though we cannot give absolute guidance in your unique situation (we're not necessarily familiar with your local codes and industry requirements), always feel free to reach out to support@watchmark.cloud with any questions and we'll do our best to answer them!