Low-Voltage (ELV) Systems: Cabling, Security and Building Systems

What is the difference between low-voltage and power systems?

Power installations deliver energy to a building; low-voltage (ELV) systems carry information and signals. The two run side by side in the same building, but they are designed and installed as separate disciplines.

Separation distances between the two installations and earthing are set by the relevant standards and the project design. A fire detection system also runs at low voltage, but because it is a life-safety system we cover it separately under fire protection systems.

How does a low-voltage (ELV) project run?

An ELV project starts with a discovery that looks at all the systems together rather than one by one. Once the shared cabling and cabinet plan is in place, the systems are installed and tested in sequence.

1. Discovery call: we discuss the building, its users and the systems you need.
2. Site survey: cabinet locations, cable routes and the existing installation are inspected.
3. Shared infrastructure plan: cabling, cabinets, power and network needs are worked out for all systems at once.
4. Proposal and schedule: the order in which the systems will be installed is set out in writing.
5. Installation: passive infrastructure goes in first, followed by active devices and systems.
6. Testing and integration: each system is tested on its own, then the scenarios between them are tried.
7. Handover and maintenance: documentation and user training are delivered and maintenance is planned.

Which low-voltage systems matter most in which type of building?

Not every building needs every system; the need depends on how the building is used. The table below sums up the combinations we discuss most often in discovery calls; the definitive list comes out of the survey.

How do low-voltage and fire protection systems work together?

A safe evacuation during a fire depends on the low-voltage systems being correctly linked to the fire alarm panel, so both should be considered together from the start of the project.

We cover detection, suppression and passive protection on our fire protection systems page; for example, fire detection and alarm systems deals with the panel at the heart of these scenarios.

• When the fire alarm is raised, card-controlled doors on escape routes are released.
• Lifts are sent to a designated floor, and ventilation and smoke control are managed according to the design.
• Background music and paging give way to the voice evacuation message triggered by the fire panel.
• Cameras covering the alarm zone can be brought up on a monitoring screen, and the building management system logs the event.

What should you prepare before starting a low-voltage project?

A few pieces of information make the discovery call far more productive. You do not need all of them, but sharing what you have speeds up planning.

• Architectural plans or floor sketches (and electrical and ELV drawings, if available).
• Building-specific usage figures such as the number of users, desks, rooms or beds.
• A list of the systems you need and their priority.
• The state of the existing installation: what will be reused, replaced or removed.
• Spaces that can be set aside for cabinets and a comms room.
• Working conditions: whether the building is occupied and which hours are available.

What are the common mistakes in low-voltage projects?

The most expensive mistakes come from planning the systems at different times, each without knowledge of the others.

• Running separate cables for every system: without a shared cabling plan, ceilings are opened again and again.
• Forgetting cabinets, power and cooling: once devices are installed, cabinet space and power become a problem.
• Accepting handover without documentation: without a cable schedule and drawings, every fault starts with a new survey.
• Leaving fire scenarios until last: door and lift interfaces are hard to add later if they are not planned from the outset.