Fire Alarm Installation
What is required when carrying out a fire alarm installation? What skills, knowledge or equipment do I need? To be considered a fire alarm installer, you must have certain attributes and hands-on-skill to competently install the containment, fire rated cable and fix the equipment to the building fabric, i.e. fire alarm control, smoke detectors, manual call points, sounders, interface units, etc.
Due to the critical nature of a fire alarm system which is usually installed to protect life or property, the installer must be fully conversant with the fire alarm design code; BS 5839-1:2013 Fire detection and fire alarm systems for buildings. Code of practice for design, installation, commissioning, and maintenance of systems in non-domestic premises.
The fire code provides guidelines and recommendations as to what is expected when installing a system. This can be located in the following sections:
Section 37 Installation Practices and Workmanship
Section 38 Inspection and Testing of Wiring.
The code states that the installation workmanship and practices should conform to the Electrical wiring code BS 7671. This particularly applies when considering earthing or the mains supply required to power the fire alarm control panel.
Therefore, it is considered that a good installer must have good practical skills and a good understanding of the theory of the fire alarm code, Electrical Wiring Code and how the fire alarm system that they are installing actually works. Having this knowledge will greatly assist installing a system to a good standard.
Before starting any installation the installer should be thinking about Health and Safety and carry out an onsite Risk Assessment and prepare a Method Statement also know as RAMS. The obvious risk when carrying out a fire alarm installation is falling from a height or if installing any 230v supplies then it will be electrocution. Once you have completed your RAMS, you can start the installation.
The first stage will be for the installer to review the drawings and confirm that what has been proposed is feasible and they understand the design. This would involve checking the proposed cable routes and consider what is the best routes that would conceal the cables to reduce the amount of wiring or containment on display. Searching out the vertical risers or horizontal voids would be part of this process.
The type of cable that is used on fire alarms must be fire resistant. It is either MICC which is short for Mineral-Insulated Copper Clad or the soft skin cable such as FP200. Due to the higher cost of MICC in terms of the cable itself and the prolonged time to install, ninety-nine percent of installations use the soft skin cable.
It is important that the installer has a complete set of hand tools, ranging from, screwdrivers, cutters, leveller, cable rods, hammer, pliers; a good set of power tools, such as drills and saw, plus an electrical test meter.
Usually, within the construction industry or large systems, the installer may be unable to install everything in one phase and therefore, will have to plan the job over several visits.
The first visit, which will be the installation of containment and cables, is called the first fix. As the job progresses and the majority of the partitions and ceilings are in place, the installer will return to install the field equipment to the ceilings and walls, and this work is known as the second fix.
The test meter is required, as all installed cables will need to be subject to an insulation resistance test of 500V d.c. But before this test is carried out, it is imperative to ensure that there is no fire alarm equipment connected. Leaving the equipment connected when carrying out this test will totally destroy the equipment as fire alarm equipment is usually designed to operate at 24v DC.
The installer should test between the conductors and each conductor and earth. The resistive value must be above two megaohms for each test. earth and loop continuity are also required.
Therefore, it is advisable, that the cable is tested before the equipment is connected.
Below is a list of the necessary test that should be undertaken.
- Installation resistance test
- Polarity Test
- Loop Continuity Test
- Earth Continuity Test
- Manufactures Loop Resistance Test
There are different types of fire alarms and they are not all installed the same way. You have addressable systems that have the detection circuit wired in a complete loop; however, with a conventional system, the circuits are radials with an EOL (End of Line Resistor) or monitoring device. An Addressable system will have the detection, alarm devices such as electronic sounders and outputs all wired on the same two core circuit that starts at the control panel and returns to the same point completing a ring. Conventional systems have the detection and Sounders on different circuits unless it is a Sav-wire system.A Fire Alarm Installation Certificate will need to be completed by the installer on completion of the works.
A Fire Alarm Installation Certificate will need to be completed by the installer on completion of the works.
Fire Alarm Commissioning
On completion of the fire alarm installation of the wiring, cable testing and the fixing of all the equipment, the next stage in the process is to get the system commissioned by a competent person. This can be the same installer if he has the required skills or the commissioning can be carried out by a different person or company, which is sometimes the case. Whichever way the relevant test results should be handed to the person who will be responsible for the commissioning works.
The Role of the Commissioning Engineer
The Commissioning engineer has one of the most important roles ensuring that the fire alarm complies with the proposed design and the requirements of the fire code BS5839. The reason for this is the designer is usually working from a specification and drawings, and may also be independent of the builders. As the construction of a building takes place the architects and the client will usually amend the final building layout and this may have an impact on the fire alarm design. However, the fire alarm designer is not always informed of these structural amendments and therefore the design is outdated and may not be correct to the final layout.
However, the one person that will be able to confirm whether any structural changes has affected the fire alarm design will be the commissioning engineer as they are inspected and testing the system with everything in place. For this reason, it is imperative that the commissioning engineer fully understands, the Fire Code BS5839, the principle of the design and the fire alarm specification.