Model Cable System Directives (MLAR)

The MLAR deals with the installation of cable systems in buildings and specifies fire protection requirements for the laying of electrical cables.    

The overriding aim is to prevent the spread of smoke and fire in the event of a fire and not to reduce the fire resistance classes of adjacent components.      

The MLAR only becomes legally binding when the individual federal states transpose it into their respective state law.   

The MLAR applies to:

• Necessary corridors, with the exception of open corridors in front of external walls 

• Cable runs through room-enclosing components (ceilings and walls)  

• Cable systems in necessary stairwells 

• The circuit integrity maintenance of electrical wiring systems in the event of fire.  

• cable ladders

• cable trays

• single clamps

• collective clamps

• wide span cable tray 

The laying of electrical cables in particular, in conjunction with the advancing technological possibilities of the electrical engineering sector, is constantly presenting planners, engineers and electricians with new challenges. 

But in the end, it's not just about material assets, but above all about protecting human life - and professional compliance with these guidelines and the use of tested installation systems is a basic prerequisite for this.  

• Preventing the spread of fire and smoke at cable penetrations in fire-resistant ceilings and walls 

• Securing usable escape routes by restricting the installation of flammable cables    

• Ensuring the circuit integrity maintenance of electrical cables.  

Another main focus of the MLAR is the transmission of smoke and heat through ceilings and walls. According to the Model Building Code (MBO), cables may only be routed through fire-resistant walls and fire walls if there is no risk of smoke and heat transmission.

The remaining opening around the cables fed through must be closed in such a way that the fire resistance of the ceiling or wall is not weakened.

There are two options here:

1. The routing of cables within fire-resistant installation shafts and ducts.
2. Partitions that isolate potential fire compartments from each other. The aim is to prevent the flames from being supplied with additional oxygen. 

Efficient fire protection within a building cannot be ensured without fire barriers at wall and ceiling openings.
If the building has no penetration seals, there are no separate fire compartments and the fire can spread effortlessly. 

The Model Cable System Directive is a model guideline for structural fire protection issued by the Conference of Building Ministers. The guideline only becomes legally binding when it is implemented by the federal states in their respective state legislation.

The aim is to install sufficiently fire-protected cable systems and is therefore decisive for the functional integrity of cable support systems.