While up to some years ago, analog telephony systems were still
commonly used in buildings and were setup by using multi-pair copper
telephone cables connecting the PABX (Private Automatic Branch Exchange)
to telephone sets, they are now almost totally replaced with VOIP
(Voice Over IP) solutions that require no separate cabling and depend on
the building’s LAN infrastructure for the interconnections.
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!
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.
LAN and WLAN
LAN
stands for Local Area Network – also known as SCS (Structured Cabling
System). Simply put, it is the data cabling in the building to enable
users to network their computer devices and possibly access to internet.
In a small building, this can be simply CAT6 cabling from an MDF (Master
Distribution Frame – i.e. equipment rack) while in larger
infrastructures, you usually see multiple IDFs (Intermediate
Distribution Frame) interconnected by fiber optic cables. (It is
interesting to know that while we have no electricity passing fiber
optic cables, they are still categorized as “ELV”!)
WLAN stands for Wireless LAN which is the network of wireless access
points that provide wireless network coverage within and outside the
building.
As you will see below, as the technologies enhance, more and more other ELV systems depend on LAN infrastructure of buildings.
Telephony Systems
While up to some years ago, analog telephony systems were still commonly
used in buildings and were setup by using multi-pair copper telephone
cables connecting the PABX (Private Automatic Branch Exchange) to
telephone sets, they are now almost totally replaced with VOIP (Voice
Over IP) solutions that require no separate cabling and depend on the
building’s LAN infrastructure for the interconnections.
CCTV
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.
ACS
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.
IDS
IDS
(Intrusion Detection System) is the common name for a broad range of
technologies which as the name suggests, alerts on any attempt for
intrusion to a building or premises. They include long and short range
radar systems, fiber optic cable systems connected to fences, IR motion
detectors, CCTV video analyzing software, and many other technologies.
Fire Alarm
Fire
Alarm Systems (also abbreviated to FA or FAS), can be divided into two
main types – conventional and addressable. Most FA systems still use
2-wire electrical cables for interconnecting of the sensors (smoke,
heat, combined) and beacons/alerts to the control panels. Newer fire
alarm solutions also provide LAN connectivity for integration with other
systems.
PAS / PAGA
PAS
(Public Address System) or PAGA (Public Address and General Alarm) is
the speaker system installed in buildings for making announcements,
playing background music and broadcasting pre-recorded alarm
notifications, sometimes automatically triggered by fire alarm systems.
PAS is probably one of the few ELV systems that is still not much IP
based and use twisted-pair electrical cables for connecting the
distributed speakers to the power amplifiers. However most of newer PAS
systems have accessories to enable utilizing LAN infrastructure for
interconnecting the main components and provide a distributed design.
SMATV / CATV / IPTV
SMATV
(Satellite Master Antenna Television), CATV (Cable Television), and
IPTV (IP Television) all explain different technologies to provide a TV
distribution system within a building, interconnecting multiple
television sets to a single source (usually called Head End) so each
television can select the desired watching channel from a selection
list.
While SMATV and CATV have their separate cabling network based on
coaxial (or sometimes fiber) cabling, they are rapidly being replaced
with IPTV solutions which rely on the same LAN infrastructure jointly
used by other systems.
Home Automation
Home
automation systems include a very broad range of technologies for
monitoring and controlling almost everything in the building from lights
to doors to home appliances and audio equipment and in short whatever
works with electricity in the building. Most home automation solutions
are now network based and give the option of remotely controlling and
monitoring the building over the internet. While in the past, most home
automations were using some remote control device, with advance of
technology the means of control is now moved to smartphone and tablet
applications or voice recognition solutions.
Above are merely samples of ELV, and there are myriad other systems
which are not discussed above that are collectively named as “ELV” in
construction terminology. One wonders, isn’t it the right time that we
change the name to something that better explains what all these systems
are all about? What about MIT (Modern Infrastructure Technologies)?
About Vizocom
Vizocom is a leading ICT and ELV solutions provider with over 25
years of experience in design, installation and commissioning of the
complete portfolio of ICT and ELV solutions, including structured
cabling, microwave, VSAT, telephony and VOIP, Video Conferencing, safety
and security systems, PAGA and SMATV and IPTV solutions.
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