FAQ Security Systems

Security systems engineering is a broad, complex field. The FAQ section will shed light on some of the more puzzling issues and provide answers to important frequently asked questions.

Modern access systems guarantee excellent protection for your premises thanks to various mechanisms. The combination of different access media such as keys, tags or cards further reinforces this. Professional planning and implementation as well as regular maintenance of your access system are essential for security. This prevents unauthorised access and the creation of illegal copies of your keys. Electronic access systems also offer the option of promptly deactivating access media if they are lost.

When choosing an access system, it is important to consider how the property to be secured is used, how many people require access and how much these numbers fluctuate. A mechanical access system is suitable if, for example, neither the authorisations nor the number of keys issued change frequently. This can be the case, for example, in residential buildings or in smaller companies. Large organisations typically require a higher degree of flexibility in terms of access control, partly because access authorisations usually change more often. In this context, an electronic access system is a good option.

There are several factors that you need to incorporate into the planning of your master key system to ensure a high level of security and efficiency. This includes, but is not limited to:

  • Number of doors and entrances to be secured
  • Individual security requirements for the premises
  • Type of cylinder required
  • Organisation size and complexity
  • Number of users
  • Frequency of changes to access authorisations

Depending on your requirements, you can choose between mechanical, electronic or combi master key systems. Feel free to use the EVVA AccessDesigner to easily plan and order your individual master key system. We can also recommend our white paper on modern master key systems. Of course, we also support you in person. We look forward to hearing from you and will be happy to advise you on the best solution for your organisation.


Resistance classes classify the capacity to resist burglary. They define how resistant windows and doors are to attempted break-ins. The higher the class, the longer burglars need to force entry and the more likely it is that they require professional tools.

These resistance classes are divided up according to the tools and work methods used in order to make a comparison on a European level and categorise such elements in line with EN1627-1630.

EVVA keys are protected in several different ways to ensure unauthorised key copying is as difficult as possible:

1. Technical & technological key protection

EVVA locking systems are developed in the in-house design department and meet very high technical standards. They can only be manufactured using specially constructed machines.

2. Managed key protection

Only authorised key holders are able to order new keys from EVVA or an EVVA partner. A security card supplied with the cylinder upon purchase is used to identify such key users.

3. Legal key protection

All EVVA locking systems and key profiles are patented.

Always measure from the middle of the mortise lock guard (cylinder fastening screw) to the outer edge of the door, including the fitting width.


36 mm (length A)+ 31 mm (length I) = 67.0 mm total length i.e. 36 + 31 = DZ 36/31


You can find information here on how to install, use and look after your cylinders properly.

A master key system means that it is possible for people, who are authorised to access different doors within a system, to each have just one key.

Benefits for you:

  • Security with as few keys as possible
  • Easy use, as only one key is needed for all relevant doors
  • Simplified organisation
  • It is possible to define exactly who has access to which areas
  • All cylinder locks and types (main entrance doors, internal doors, garage doors...) can be locked with just one key

The following overview shows clearly the four different master key systems. Your EVVA support team or EVVA partner will be glad to provide you with information as to which type is perfect for your property.

The general main group key system

Several main groups with subordinate group and own keys are combined under a general master key in accordance with the hierarchical structure of a company (for complex organisation such as administration and infrastructure companies, industry, etc.).

The main key system

The main key system is one with different locking cylinders to which a master key is assigned (e.g. for the commercial sector).

The central lock system with technical master key

For housing developments for example. Individual flats have different locking cylinders. Each flat resident locks the flat and the main entrance door with his/her key. A master key can also be provided which locks all engineering rooms.

The combined master key system

In addition to the mechanical master key system, doors are also protected with an electronic locking system. The mechanical, and also electronic locking system, can only be operated by the user with an ID (combi key).

Emergency opening with BSZ function

A locking cylinder can be blocked from functioning when a key is inserted in the lock. This can pose a safety hazard, particularly in the event of an emergency.

What can be done, for instance, if a member of your family or a hotel guest always leaves their key in the lock on the inside and there is an emergency? The solution: EVVA double cylinders can be optionally fitted with a BSZ function. BSZ is a function which allows the cylinder to be locked from both sides, even if an authorised key is inserted on one side of the door.

Emergency opening with override function

In the event of an emergency, controlled access to all rooms must be possible at all times, particularly in companies. EVVA offers the option of a so-called lock override: This is when a person with an authorised key can take the locking system general master key or group key in a controlled way and thus have access in the event of an emergency.

The general master key must also be available to emergency services such as the fire service in the event of a fire or other emergency. The key can be securely stored in an EVVA tubular safe.

Have you found an EVVA key in the office, on the street, on the train etc. and you don't know who it belongs to? Please would you return the key, with information on where you found it, to one of the following places:

  • the lost property office of your local council
  • or to a nearby EVVA subsidiary

EVVA would like to thank you for your help and your honesty!

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