According to the International Electrotechnical Commission, ELV (Extra Low Voltage) is defined as any system operating in a voltage not exceeding 35V AC (or 60V ripple free DC). Although the term is technically correct from “electrical” point of view, it by no means describes the broad range of systems and technologies which are known as ELV systems in buildings. ELV is the terminology used in the construction world in an attempt to electrically define all the systems in a building which need electricity to run but are not part of the building’s main electrical system. ELV covers all the new modern technologies that are increasingly becoming must-have systems in every building such as data network, CCTV, fire alarm systems, public address systems, audio/video solutions, access control and intrusion detection systems, home automation, and much more! ACS- is the abbreviation for Access Control System. ACS systems give access to different building locations (usually implemented by automatic unlocking of doors) through different means of authentication of people (by magnetic or RFID identification cards, by finger print, IRIS or face recognition). Almost all new ACS solutions also rely on LAN infrastructure to some extent, while they also include electrical cabling to magnetic door locks, manual push buttons, and magnetic sensors installed on the doors and entry gates. CCTV stands for Closed Circuit TV (again a very old acronym which shows the old “electrical” roots of such systems). Simply put, these are the camera systems setup inside and outside of buildings to provide monitoring surveillance. Old analog cameras used a separate cabling of coaxial cables connecting each camera directly to the DVR (Digital Video Recorder). These are also today almost totally replaced with IP Cameras utilizing the common LAN infrastructure of the building. The fact that such a broad range of technologies are collectively named “ELV” shows probably how much we are lagging behind the new demands of 21st century. Below I will very briefly explain some of the confusing abbreviations that constantly pop up when discussing ELV systems.