Master Key Systems MKS Limited
Master Key Systems MKS Limited
01902 737 672

Master Key Systems Explained

A Master Key System is a mechanical access system whereby a single key can open all the doors with cylinder locks within a complex or business. This is the simplest explanation, but to fully understand as to why cylinder locks are the best lock option for single or multiple key accesses, a more detailed explanation is needed.

HMO / Multi Occupancy Locking Systems

HMO / Multi Occupancy Locking Systems

Our web site shows in graphic form how this works. There can be many levels to a cylinder master key system. A basic system is where all cylinder locks are opened by a single Master Key but each of the door cylinders are opened by their own key often referred to as the slave or differ key.

This system is typical for a HMO or Landlord whereby the Landlord wants his own single Master Key to open all the locks, but to ensure that the tenant has a differ key that is unique to their own door.

Very often, the Landlord will also have a Cylinder Lock fitted to the main door. This door cylinder can be opened by the Master Key and each of the tenants keys and this is referred to as a common entrance. Whilst this is not recommended, it is by far the most convenient Master Key System for HMO’s and landlords.


Euro Cylinder Locks

Euro Cylinder Lock Master Key Systems are in most circumstances, commissioned for convenient access whilst being able to work with a more complex Master Key System and limit access to individual key holders. All of this is possible because of the unique design of door cylinder locks that have been developed over many decades and re-engineered in recent years to tolerances that allow them to be Master Keyed.

Before designing or commissioning a Euro Cylinder lock Master Key System, a degree of careful thought should be given to what is required of the system by the principal (Master Key Holder) and the other users whilst allowing for expansion (as more users may need to use the system in the future). The starting point for this process is to determine how many doors there are that will require cylinder locks and how many extras may be required over the forecast life of the Master Key Suite.

A basic Master Key System Planner is available from our website. If something more complex is required, then MKS have a range of Excel charts to suit all types of Master Key Systems however complex.Having decided on the elements of doors, cylinders and users plus allowing for future expansion, the next level is deciding the levels of access, for example you may require some doors to be opened by more than 1 user but exclude others from individual key holders or Sub Master Key holders.

What Type of Master Key System To Use

At this point a decision can be made as to what type of system is required, this can be any of the following:

Great Grand Master Key System - this is typical of very large systems i.e Academy’s or Hospitals etc where there are a large range of individual users requiring access to areas that their expertise/discipline require.

Within this system will be a Grand Master Key. This will operate all the cylinder locks except those exclusive to the Great Grand Master key. Below this will be individual Master Keys. Again, only opening designated door cylinders but not those exclusive to the Grand Master and Great Grand Master. Below the masters can be Sub Masters and then differ keys.

Having decided the structure of the cylinder Master Key System, thought must be given to the type of door cylinders to use, the most common in use today being the Euro Cylinder Lock, this refers to the shape of the extrusion used in the manufacturing process.

There are a large variety of euro cylinder locks starting with the single or half cylinder used where access is of the door only required on one side, as there is only a key way on the one end. These come in a range of lengths from 40mm up to 70mm as standard to suit individual door and furniture thickness’s.

Some doors will inevitably require a door cylinder with key access both sides, these are referred to as double cylinder locks or Key Key cylinder locks. As with the single cylinders, these are available in a variety of lengths and combinations to suit most modern and conventional door designs. The smallest standard euro cylinder lock suitable for Master Keying is 60mm in length, this is on an equal sided cylinder. i.e. either key side is 30mm from the key face of the cylinder to the centre of the operating cam.

Traditional Cylinder Locks

Traditionally Cylinder Locks were measured excluding the operating cam for example, a 60mm euro cylinder would be specified as a 25/10/25 the 10 being the dimension of the cam.

Today this is not so common. With the advent of PVCu doors and large security doors, it has brought about the need for offset cylinder door locks. As an example, a 100mm cylinder could be spit 40/60 ie from one end of the cylinder to the centre of the cam it measures 40mm and from the other end 60mm.

This change in the market has required the manufactures such as Master Key Systems MKS to ensure they carry a range of offset euro cylinder locks, capable of being Master Keyed.

By far the most specified Euro Cylinder is the Cylinder and Thumb Turn or key & turn. This has a key access on the outside, with turn on the inside which will lock and unlock the door lock.

This type of cylinder is an absolute must when fitted to a final exit door in any public or managed spaces or accommodation. As with all other euro cylinder locks, a cylinder with thumb turn comes in a variety of sizes, both equal splits and offsets.

Traditional Cylinder Locks

Having established what is required of the system, how it's to work, how many cylinder locks are required, what sizes are required and who is able to open which cylinder locks, the user must decide what level of key and cylinder security is required. This can be a simple open key system whereby the master key holder and individual key holders can get keys cut at a local lock smith or key bar.

This level of key security is very low and should be considered with caution and is more about convenience than security. By and far the most secure for key security is a closed or restricted system. The cylinder lock manufacturer will not issue key blanks and providing the key profile is truly restricted, they will not be available anywhere other than the Master Key System manufacturer.

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