Security Systems

Line Isolator System from Bosch Cost-efficient solution for failsafe audio reproduction for a wide range of applications

  • Assures failsafe audio reproduction in the event of loudspeaker line faults
  • Creates redundant loudspeaker loops for sound reinforcement and voice alarm systems
  • Reduces wiring cost of installations by eliminating expensive E30 cabling
  • Currently certified according to EN54 in Europe
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  • September 23, 2014
  • Security Systems
  • Press releases

press release

Munich – Through redundant loudspeaker loops for sound reinforcement and voice alarm systems the Line Isolator System (LIS) from Bosch cost-effectively assures failsafe audio reproduction in the event of loudspeaker line faults. With the Line Isolator System Bosch offers a cost-efficient solution for failsafe audio reproduction in sound reinforcement and voice alarm systems. The easy to install system dispenses with costly E30 cabling und reduces installation costs by up to 25 percent. The LIS is fully supervised and perfectly adapted to use in commercial premises such as office buildings and hotels. Typical applications include public address systems covering six to 80 zones and more than 25 loudspeakers per zone or systems where fire in one room may not lead to loss of signal in another room.
Each installed line isolator system comprises: A LIS Master Unit, a loudspeaker loop consisting of daisy-chained LIS Isolator Boards and LIS DC Blocking Boards as well as the installed loudspeakers themselves. The LIS is currently being certified according to EN54 for use in PRAESIDEO systems.

The LIS Master Unit
Each zone output of the public address and voice alarm system is connected to the LIS Master unit. A Master unit can supply a total of six (500-watt) loudspeaker loops, thereby creating a high-performance system. LEDs on the front panel display the status of each loop along with those of the mains power supply and backup battery supplies. These indicators are available as fault relays on the rear panel which also contains the interconnections and DIP (dual in-line package) switches for setup and test purposes.

The LIS Isolator Boards
The LIS Isolator Board detects and isolates line and loudspeaker faults; these could be occasioned, for example, by open or short circuits in the loudspeaker line or overloads caused by loudspeaker faults. A maximum of 50 LIS Isolator Boards can be installed in each loudspeaker loop.

Each Isolator accepts loudspeaker loads from 10 to 100 Watts; a tap-off on the isolator board allows one or more loudspeakers. Each Isolator has a Test/short LED which is also visible when the board is mounted in the supplied housing and facilitates possible troubleshooting.

The LIS Blocking Board
The LIS DC Blocking Board is equipped with a DC blocking capacitor and overcurrent protection. It has the same connections as the LIS Isolator Board, allowing for quick and convenient connection of the loudspeaker loop and tap-off connections. The LIS DC Blocking Board can be mounted inside selected Bosch loudspeakers making use of the standard mounting provisions in the loudspeaker.

The Line Isolator System from Bosch is available with immediate effect.

The Bosch division Security Systems is a leading global supplier of security, safety, and communications products, solutions and services. More than 12,400 associates generated sales of 1.5 billion euros in fiscal 2014. Protecting lives, buildings and assets is our aim. The product portfolio includes video surveillance, intrusion detection, fire detection and voice evacuation systems as well as access control and management systems. Professional audio and conference systems for communication of voice, sound and music complete the range. Bosch Security Systems develops and manufactures in its own plants across the world.

Additional information can be accessed at

The Bosch Group is a leading global supplier of technology and services. It employs roughly 375,000 associates worldwide (as of December 31, 2015). The company generated sales of 70.6 billion euros in 2015. Its operations are divided into four business sectors: Mobility Solutions, Industrial Technology, Consumer Goods, and Energy and Building Technology. The Bosch Group comprises Robert Bosch GmbH and its roughly 440 subsidiaries and regional companies in some 60 countries. Including sales and service partners, Bosch’s global manufacturing and sales network covers some 150 countries. The basis for the company’s future growth is its innovative strength. Bosch employs 55,800 associates in research and development at 118 locations across the globe. The Bosch Group’s strategic objective is to deliver innovations for a connected life. Bosch improves quality of life worldwide with products and services that are innovative and spark enthusiasm. In short, Bosch creates technology that is “Invented for life.”

Further information is available online at and,

PI8613 - September 23, 2014

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