Understand the Basics of ELV System

What’s an ELV system in a Building?

An ELV system is an intrinsic part of a building’s Mechanical & Electrical systems, for the purpose of finer safety, security and control.

Whereas ELV stands for Extra Voltage System,

Broadly used in every building, regardless of its magnitude and dimension, so clearing the myth the ELV system to be used only in high rise structures.



The governing body The International Electrotechnical Commission (IEC), defines this category of voltage as <50 V in the case of an a.c or 120V for d.c

Well, we will follow the industrial standards. The System integrators & the OEM, seemingly the building automation systems operating with a direct current for their working fall under this segment.

A number of systems fall under this segment, working together with an integrated approach to serving its purpose namely;

  • Fire alarm system,
  • Public addressing system
  • Closed-circuit television,
  • Door access controller system
  • Physical barrier systems namely bollards, turnstiles, barriers
  • Audiovisual system
  • PBX (Voice networking)
  • IT Infrastructure,
  • Home automation,
  • Network data security
  • Professional display & signage
  • Nurse call system

And many other myriads systems which we will discuss in this forum in an “Exploded manner”, designed exclusively to suit & furnish the needs of modern infrastructure from its inception.


Decoding the connection between ELV, BMS & HVAC

Another term allied with ELV is BMS, which stands for Building Management System also known as IBMS and BAS in Americas and the European countries.

Hence to say in layman’s language where all these sub-systems are all put together and made to control and monitor into a whole for effective functioning.

Thus the systems are divided into suitable predefined IO points i.e. Input/output.

IO Points are further categorized into analogue & digital, with suitable field devices. & sophisticated third party devices fixed in a building ranging from grounding an elevator to monitoring the water level of a sump to monitoring & controlling the properties of HVAC (Heating, Ventilation & Air Conditioning) equipment that is the Temperature, RH, Pressure.

Thus leaving every stone unturned it encompasses the majority of a subsystem and parameters as a whole.

The Protocol

To say in simple terms the language of systems is used inside the building for the purpose of safety, security and betterment.

Commonly used is the BACnet protocol a subsidiary of ASHRAE.

Every application in the building has BACnet protocol, such as HVAC, Safety security systems, fire, lighting other control systems etc. expanding its horizon.

There are other protocols like the RS485/RS232 which limit the scope of scalability.

For instance, we’ve cleared the air for beginners which is portrayed like a climax of a witchcraft movie!


The term Interoperability

Well, it seems alien, different systems talking to each other which has a unique role to play in a building, thus giving birth to the term Interoperability.

Interoperability is the ability of systems to communicate with each other in a building.

Therefore the subsystems have a protocol that enables them to communicate with each other, for the purpose of monitoring & controlling.

Ethernet technology

Another technology binding to this system is the Ethernet, which Commercially made its mark in the 90s.

Used in linking computers, printers, and peripherals, till date used in ELV and building automation systems.

Therefore the IP enabled device is wired physically in the network, with an objective to communicate with the prescribed standards of IEEE 802.3.



Thus to have an integrated approach for an effective Building Management System following factors should be taken into consideration;

Scalability: Vital for any system to scale up the requirement of a growing infrastructure

Open standards & protocols: With the evolving technologies it is practical to have open standards for the purpose of interoperability; proprietary controls will have undesirable consequences

The software gets upgraded at the successive intervals,

Baud rate within the specified ranges to integrate

Factors like the Manageability, the ability to remotely manage the systems, several other factors which might arise while implementing the setup, and user-friendliness lend the facilitating staff of the building a helping hand.

Projecting such scenarios will inherently reduce the economic factor OPEX and CAPEX.

Wrapping up the session on showcasing the relationship between ELV, BMS & Controls (HVAC, sophisticated third party systems which are installed in the building)

Stay tuned for further exhibiting the basis of the recent trends in this niche field of the ELV and IBMS.

Author Details

a Mechanical Engineer by profession and a Design engineer at Johnson Controls Ventured into the profession of ELV-BMS-HVAC.
Certainly, like myself spending time in this profession and a passion for this subject interest drove me to demonstrate how the system functions. Recent trends in this niche field and to provide Design engineering solutions as per the standards.
Now I have an opportunity to put my feet, words and mouth in this arena, ultimately an amateur blogger with cheerful compliance to write!

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