This website uses cookies primarily for visitor analytics. Certain pages will ask you to fill in contact details to receive additional information. On these pages you have the option of having the site log your details for future visits. Indicating you want the site to remember your details will place a cookie on your device. To view our full cookie policy, please click here. You can also view it at any time by going to our Contact Us page.


Getting in the zone

Electrical contractors know only too well the importance of getting fire alarm systems right, whether for a domestic property or a commercial one, but how much of an impact do other factors have on what they install?

Keeping up with legislation and building regulation changes, as well as new technological advances, is a job in itself and could mean that the most appropriate product is not always installed. Here Gary Walker, Newlec fire safety category manager at Newey & Eyre takes a look at the changes within the sector and the product choices available.

With the introduction of the Regulatory Reform (Fire Safety) Order and changes to British Standards, there is
now a requirement for both companies and personnel working within the fire industry to be not only competent but be able to prove this competence. In tandem with these regulatory changes during the past two years, the fire alarm systems themselves have also been going through a period of significant change. Generally the industry uses three main types of system; conventional, Bi-wire and addressable. Conventional two wire systems use end of line monitoring or active end of line modules with separate sounder circuits, and in commercial buildings the established conventional system revolves around dividing the building into a number of zones, where the detectors and call points within each zone are then
wired on dedicated circuits.

In the event of a detector callpoint being activated the panel is able to determine which circuit contains the
triggered device and thereby identify which zone the fire is coming from. In addition to the detection circuits there is also a need for separate circuits for alarm annunciation, as devices such as sounders and beacons need to signal the existence of a fire to the building’s users.

For sounder circuit continuity monitoring to function effectively, sounder circuits must be wired in a single radial circuit - spurs and tees are not permitted. Every conventional fire panel will have two or more sounder
circuits, (depending on the panel manufacturer this could have two or four). Normally however, there will be
less sounder circuits than detection circuits, so it will be necessary to provide audio coverage for more than one zone, therefore increasing the complexity and cost of the installation by forcing the sounder wiring to follow a different route to the detector wiring.

Through advancing technology the way forward involves a new method, which is appealing to installers as it enables a much quicker installation time. Based on conventional technology it incorporates additional functionality to enable both the detectors and the sounders for each zone to be wired on a single common
circuit. Bi-wire or two-wire (as it’s also known) fire alarm systems, allow detection devices and sounders to be wired on the same two core cable. “Although Bi-wire detectors increase outlay, this is offset by savings in installation.”

Even though the panel continually powers the sounders, the additional control functionality within each one
enables them to be activated only in the event of a fire alarm condition. By combining the detection and alarm
annunciation wiring into a single circuit, both time and cabling can be greatly reduced. Although adding Bi-wire technology to the detectors and sounders slightly increases equipment outlay, this is normally more than offset by savings in installation, resulting in a reduced total cost.

During the past months not only fire alarm systems have advanced, smoke detectors have also seen a
period of transition thanks, in the most part, to the enforcement of new EU regulations. Ionisation smoke detectors contain small ionisation air molecules that have a high sensitivity to fires that produce small smoke particles. Despite them having been the favoured option for a number of years, these are now being phased out. This change to the optical only system is to comply with The Restriction of Hazardous Substances (RoHS) and WEEE regulations, as the ionisation models contain small levels of radiation material and so are more difficult to dispose of safely and makes recycling impossible.

Photoelectric smoke detectors are now the preferred option and these are activated when light from a pulsating light source is reflected off the smoke particles onto a light sensor, triggering the alarm. These smoke detectors are particularly well suited to detecting slowburning, smouldering fires that produce smoke with large particles and have been taking over from the ionisation models for some time.

In addition, self check detection devices are new to the market and work like ordinary conventional detectors, but incorporate additional circuitry to constantly monitor their own status and raise an alarm, both locally and at the fire panel in the event of a fault. Self check detectors represent a major innovation, greatly
enhancing the integrity of conventional fire alarm systems. With traditional systems, the monitoring element is within the control panel, this checks that all detectors are in place and the wiring is intact, they do not however, verify that the detectors are actually working. The new self check range of detectors constantly monitor themselves and raise an alarm in the event of failure.

For a more advanced option, which incorporates similar technology to the Bi-wire method, addressable analogue systems offer point identification. This reduces search time, detection devices, sounders, repeater fire alarm panels, and an array of modules all connected on two wires in a loop configuration giving
optimum integrity. With these systems you can generally connect up to 125 devices per loop, however dependant on the panel manufacturer some systems can exceed this number. Most addressable systems can also be networked, in some cases this can be advantageous in reducing cabling and system integrity.

As any electrical contractor knows however, it is not just alarms and detectors that are crucial in fire safety
but emergency lighting also plays a critical role. The advent of LED lighting technology is signalling the way out for the standard lamp as the benefits of LEDS are realised. By using strips of small LED lights rather than a fluorescent tube, the products last longer and are more cost effective to operate, which is appealing to any end-user. Installers should be advocating their use not only from a quality standpoint but also as a
key way of reducing energy usage, a major factor in the choice of products now specified.

As the technology within fire safety products continues to advance, it offers the contractor even more choice in how to install the best products with the minimum installation time, and lessen the potential for false alarms or problems. When installing any fire safety product the key factor has to be quality and in an emergency such as a fire, their integrity is tested to the full, which is why all products must be manufactured
in an ISO 9001 facility and tested and certified to BSEN54 parts 2 and 4. Finally, it is essential to understand the variety of products available, so the most appropriate is used and that all components are fully compatible with each other.

Newey & Eyre has 160 plus branches throughout the UK. With more than 20,000 product lines in stock at any one time, it holds more major brands than any other electrical wholesaler.

Contact Details and Archive...

Related Articles...

Print this page | E-mail this page

Electrical Products