Commercial Fire Alarm Installation: From Survey to Certified Handover

Who decides what the system should cover?

The responsible person, using the fire risk assessment. The installer designs to that decision.

Under the Regulatory Reform (Fire Safety) Order 2005 the responsible person must provide a suitable means of detecting fire and giving warning. What counts as suitable comes from the fire risk assessment. If you have one, the alarm specification starts there. If you do not, the assessment comes first.

A good installer will ask for it. One who quotes a system without asking about the risk assessment is guessing at the category. Our page on who can install fire alarms explains what to look for in the company you choose.

How the category is chosen, in plain English

The category says where the detectors go. It is the biggest single factor in the size of the system.

• L1. Detection in every area of the building, including roof voids and small cupboards. Used where life safety is the main concern, such as sleeping accommodation.
• L2. Detection in escape routes, rooms opening onto them and high-risk rooms such as kitchens and plant rooms.
• L3. Detection in escape routes and rooms opening onto them. Aimed at giving people time to get out.
• L4. Detection in escape routes only, such as corridors and stairs.
• L5. A bespoke design for a specific risk, set out in the fire strategy.
• P1 and P2. Property protection. P1 covers the whole building and P2 covers defined high-risk areas. Chosen to protect the building and its contents, often for the insurer.
• M. Manual only: call points and sounders, no detectors. Used in small, low-risk premises where people will notice a fire quickly.

The longer explanation is on fire alarm categories explained. Categories can be combined. A hotel may be L1 in the bedrooms and corridors and P1 in the plant. We never choose the category to make a system cheaper.

Conventional, addressable or wireless?

All three can meet BS 5839-1. The choice is about the building, not about quality.

• Conventional. Detectors are wired in zones. When one activates, the panel shows the zone but not the device. Suits small, simple buildings with a handful of zones.
• Addressable. Each device has its own address on a loop, so the panel names the exact detector. Faster to find a fault or a fire, and easier to extend. Most mid-size and larger buildings use it.
• Wireless. Devices talk to the panel by radio. Useful in listed or occupied buildings where cabling is difficult. Batteries and signal strength need planning at design stage.

We go through the trade-offs in addressable vs conventional and wireless fire alarms. For larger systems we usually fit panels and devices from Advanced, Apollo and Hochiki, which we know well and can support for years.

Our process, start to finish

The same sequence on every job.

1. 1Survey. We walk the building with the risk assessment and plans, noting construction, ceiling heights, risers, kitchens, plant and any places with false alarm risk.
2. 2Design. We produce a design to BS 5839-1:2017 with device positions, zone layout, panel location and a cause and effect schedule for doors, lifts, ventilation or any other linked equipment. You approve it before work starts.
3. 3Installation. Cabling, devices, sounders and panel. Cable types and fixings follow the standard, and penetrations through fire walls and floors are made good with tested fire stopping.
4. 4Commissioning. Every device is tested and every sounder level measured. Cause and effect is run end to end.
5. 5Handover. You receive the installation and commissioning certificates, the as-fitted drawings, the zone plan, the cause and effect chart and a logbook. We show the responsible person how to carry out the weekly test and what the panel is telling them.

The certificates and logbook are the evidence the fire service, your insurer or a purchaser will ask to see. Make sure any installer you consider names them in the quote.

Working in an occupied building

Most of our installs are in buildings that stay open.

We plan the work in zones so that detection is never removed from an area until its replacement is live. Where an existing system is being replaced, the old panel stays working until the new one is commissioned, or we agree interim cover with you, such as a fire watch. Noisy and dusty work is booked for quiet periods. Systems that interface with doors, lifts or ventilation are tested at times that do not trap people or stop the building.

Where cabling would damage a listed or finished interior, a wireless or hybrid system is often the better route.

Questions to ask any installer

These separate a competent quote from a price for boxes on a wall.

• Which category are you designing to, and where does that come from?
• Will you see the fire risk assessment, and what happens if it conflicts with your design?
• What certificates will I receive, and will they be signed by the person who commissioned the system?
• How many devices are on each loop, and how much spare capacity is left?
• What is included in the first year, and who do I call if it goes wrong?
• Who will service it, and are you offering me a contract I do not need?

Our guide to comparing fire alarm quotes covers this in more depth. For the cost side, see how much a commercial fire alarm system costs. After handover, the system needs regular attention: see fire alarm servicing and maintenance and fire alarm testing.

Sources

• Regulatory Reform (Fire Safety) Order 2005 (legislation.gov.uk)
• Fire safety in the workplace: your responsibilities (GOV.UK)

Updated October 2026 by Sebastian Grabowski, DC Fire & Security, 2 Winsdon Court, Luton LU1 5LZ.