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Great Grand Master Keys (GGMK)

Although an increasing number of property owners are switching to electronic access control systems, many still rely on traditional keys to control and manage access.

Albeit so small, keys play a huge part in the security of a property since they allow access to the premises, its equipment, machinery, vehicles, and secure areas.

That being said, proper key management is of utmost importance and it must be made sure that only authorised individuals can access different areas of the properties while maintaining a high level of security.

One great solution for proper key management is the implementation of a master key system which works to achieve these goals and make access control much easier.

A master key system is ideal for limiting and regulating access and has various levels that are used to open one or more doors on the property.

Read on to find out more about master key systems, what great grand master keys are, how they are used, their advantages and disadvantages, and much more:


A master key system refers to a group of locks and their corresponding keys that are related in a hierarchy with one key at the top level which will open several locks and several keys at the bottom level which will open only one lock.

Master key systems can have a different number of levels, and the fewer master key levels the system has, the more secure it is. Regardless, proper planning is crucial.

They are especially beneficial for properties with several doors, access points, and users since they eliminate the need to carry huge sets of keys and reduce the number of keys to be managed.

By using a master key system, building owners and administrators are able to ensure security in certain areas of the property which only the management has approved.

For example, the office manager may have one set of keys which opens the conference room and all the utility closets, but restricts access to the CFO’s office.

Similarly, the CFO may have access to their office and the back-room housing all of the business’s financial documents and the business safe, but not to the server room.

The business owner, however, would possess a master key which would allow them to access all doors within the building.


To understand how a master key system works, you need to first understand how a basic pin tumbler lock works since that’s what most master key systems work off.

A pin tumbler lock consists of a driver pin and a key pin, both of which are lifted when the right key is inserted so that they rest on the opposite side of the shear line.

The key pins will be of different sizes but the driver pins will be a universal size, and the right key will have the right set of grooves in it to lift the key pins to the required height.

To convert a standard pin tumbler lock to accommodate a master key system, a master wafer (a small pin shaped like a hockey puck) needs to be added between the driver pin and key pin.

Master keys are related to one another in a hierarchy which is clearly depicted in the master key system schematic. It refers to the diagram or blueprint that allows you to visualise the access levels and key security across the property.

The master key system schematic is used to establish your master key system and to mathematically cut keys. It also allows you to determine how the master key system will be organised, how many master keys are required, and who will be selected as master key holders before the keys are cut.


The simplest definition of great grand master keys (GGMK) is that they are the highest level in a master key system and are used to open all the doors on a property or multiple properties.

They are used to manage all the access points throughout the property, with separate master keys for each building in case of multiple properties, and are usually owned by an officer or owner of the company.

Great grand master keys give access to the entire organisation including all the doors, locations, and facilities. They grant access to all the key systems under it, including the grand master keys, master keys, and sub-master keys.

They are kept under tight security and carry an extreme security risk. Imagine losing the key that opens all the doors on not just one, but multiple buildings.

Great grand master keys must be limited to a handful of people who require complete access. The fewer individuals who have that level of access, the safer and more secure the master key system will be.

Below the great grand master keys are the grand master keys (GMK) which have a higher level of access than master keys but not as high as the great grand master.

They can be used for multi-site as well as single-site organisations and should also be limited to a few responsible individuals only.

Next in line are the master keys (MK) which are able to open all the locks below them in the system but not those associated with the grand master and great grand master.

They are used by individuals who need a high level of access within their level in the hierarchy, such as the regional or area manager, and cannot open locks outside their access area.

Lastly, we have the sub-master keys, also called change keys or user keys, which will open one lock only and locks that are exactly the same.

These are the normal keys distributed among employees within an organisation who do not need a high level of access.

They are typically associated with a single lock, such as the front door or a single room, and cannot open any other doors. Locks that can be opened with a sub-master key can also be opened with master keys and those above that level.


Master key systems are designed to make it easy to provide individuals easy access to parts of a building where they are allowed to go to, while restricting access to areas where they have no business going.

They are used both residentially and commercially and, depending on the type of property and the number of users, you can have two or more levels of master keys.

Starting with sub-master keys and going up to master keys, grand master keys, great grand master keys, great, great grand master keys, great, great, great grand master keys, and so on.

Great grand master keys are generally used for multi-site properties such as offices, retail stores, shopping centres, warehouses, factories, hotels, restaurants, cafes, schools, medical centres, hospitals, and nursing homes.


If you own an office building, commercial warehouse, or any building that has multiple doors with controlled access, you may benefit from the use of master key systems.

As discussed above, a master key system will have different types of keys that will open various doors. For instance, a great grand master key will open all the doors on the property (or a multi-site property), a grand master key will open the majority of the doors, a master key will open fewer doors than its predecessor, and a sub-master key will open just one door as regular keys do.

This hierarchical access allows you to hand out the keys to employees and other people on the property based on their access permissions and designation in the company.

Before you consider installing a master key system on your property, you need to understand its advantages and disadvantages to help determine whether it’s right for you or not.


When it comes to using great grand master keys, and master keys in general, there are several advantages, the number one advantage being convenience.

You can use a single key to open a large number of locks and you wouldn’t have to carry around a heavy ring of keys all around. Imagine the number of keys you’d have to manage when managing a multi-site property!

In addition to the convenience factor, a master key system also offers enhanced security by giving you the power to allow and restrict access for your employees and not worry about unauthorised individuals making their way into off-limits areas.

You can effectively control who has access to what and can keep individuals out of places where they have no business being. For example, if you want to limit employees’ access to spaces such as conference rooms, data centres, and other employees’ offices, you can easily do so with this type of system.

Depending on your requirement and business decisions, you may either keep the master key only with yourself or duplicate it and hand it out to a trusted employee or board member. As long as you have the original master key, you will have full authority over it and your permission will be required for duplicating it.

Another advantage of master key systems is that, compared with electronic access control systems such as key cards, they have a much cheaper upfront cost. Therefore, if you have a limited operating budget, a master key system may be the best option for you.


Being aware of the potential disadvantages and pitfalls of master key systems will ensure that you take the necessary steps and precautions to avoid them.

The main concern facing master key systems is the lost key dilemma. Losing a master key means that you will have to rekey or replace all the locks on the system to reduce the risk and vulnerability.

The higher the level of the lost master key, i.e., the grand master or great grand master key, the higher the security risk. Not only can this be unsafe and inconvenient but can also prove to be expensive. While keyless systems have a higher upfront cost, they are much safer since there are no keys to lose.

Another issue with master key systems is that of upgrading access and changing employees’ keys as they move up the designation ladder.

If you want to allow a certain individual access to a specific area on the property which was previously restricted to them, you will have to take the time out to physically swap the keys.


To make the most of your master key system and enjoy all its benefits while minimising the drawbacks, you need to focus on proper key management.

A few main factors to consider include:

Hardware keying design

This is the first step in effective master key system management and is directly related to the property’s structure.

It involves determining the various entry points requiring keyed locks and creating a security hierarchy corresponding to the access permissions within the organisation.

It requires you to determine which entry points will allow access to the general public and limited users or require high-security access control, which is something an experienced professional locksmith can help you with.

Access permission policies

This refers to the key holders and users within the system and requires you to outline who will require access through the various access points within the organisation.

Along with the access permissions, it is also necessary to assign access restrictions to the users since they determine the type of users that won’t be permitted to access high-security areas.

Key tracking

Key tracking allows the property owners to keep a record of all the key’s access permissions along with the people responsible for them.

All keys must be stamped with unique serial numbers and assigned to a particular access level. This record-keeping allows you to keep track of who the keys are given to, who approved the access permissions, and the dates of issuance and return.

Key storage

Key storage refers to providing a secure place to keep the keys, their duplicates, as well as their backup copies.

There are different types of storage cabinets depending on the number of keys included in the system, all of which make it possible to locate the keys, identify if any are missing, and track who is responsible for each one.

Many property owners are now turning to electronic key management systems, which are cabinets made of steel and require a code or proximity access card to unlock them.

In addition to providing safe key storage, they also keep a digital record of key issuances and users and send automatic notifications when the keys are not returned on time.


Calder Security has been in the security industry since 1976 and we are members of the Master Locksmith Association (MLA).

We provide all kinds of security solutions designed bespoke to your property’s requirements and are experts in both master key systems as well as electronic and keyless access control systems.

Our expert team of SSAIB approved installers can help you assess your security needs and offer the right master key system or access control system including intercom, proximity fob, card swipe, keypad, and biometric systems that work with fingerprints or retina scans.

We are experienced in creating sophisticated access control systems for residential properties, large scale commercial enterprises, as well as smaller businesses.

We offer expert key cutting services from our Lock and Safe Shop in Wakefield where you can get your keys cut while you wait. We can cut virtually any key to a high degree of accuracy without having to send them away to be cut using our state-of-the-art digital equipment and key cutting machinery.

We can also work on a wide range of locking mechanisms, are specialists in wooden, UPVC, and aluminium doors, and are the official suppliers for leading lock brands including Chubb, Yale, Securikey, and Garrison.

Contact us here or call us on 0800 612 9799 to talk to our professional locksmiths right away!

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