One of the main requirements when choosing a fire alarm system for a construction site is to ensure that it is EN 54 compliant. Of course, there are other factors to consider as well when looking for an effective way of protecting personnel and assets from fire. These include a clear means of escape and compartmentalisation to protect workers, plus managing the safe storage of hazardous materials, although these are just some of the basics.
However, of all the measures that can be taken, a correctly specified fire alarm system has the ability to make the greatest difference in terms of saving lives. This is because it is the most effective method of getting everybody off site in a speedy and coordinated manner.
When choosing a fire alarm, a technology-based system is preferable because construction sites are getting larger and more complex, which means, for example, having a safe means of escape can become more challenging to manage. Factor into this scenario the increasing use of timber frame and high rise buildings and you can see why more developers are taking a technology-based route.
There are two kinds of technology-based fire alarms that are used on construction sites; wired and wireless systems. Whichever is used it should be EN 54 compliant.
JCOP clarifies need for EN 54Wireless versus wired fire alarms
Wired fire alarms have been used for a number of years although they are losing favour because they require specialist trades to set up. Factor into this that as the site progresses these specialist trades are needed each time the units are repositioned and it is understandable why more developers are choosing wireless fire alarm systems.
We recently supplied a large new build development in Manchester. Until relatively recently they had used a wired fire alarm system but had become concerned with its cumbersome nature.
“We have used wired systems until relatively recently although we didn’t find them practical. Trailing leads were an ongoing concern because they caused trip hazards and other safety issues around site,” explained the fire officer. “Another significant factor was that wired fire alarm systems prevented us closing up elements of the build. For instance, we would hardwire each section of a development for the fire alarm system and then when it was ready to be boarded out and plastered we would have to dismantle it, carry out the work, and then reinstall the wires. When you factor in that specialist electrical trades are needed to do this, you can see why it was causing us real issues.”
These kinds of practical concerns are often cited for moving from a wired to a wireless fire alarm system. As the developer explained: “We’ve used both wired and wireless fire alarms and there’s no comparison – wireless wins hands down, every time.” To emphasise this they pointed out that the WES+ wireless frequency passes through all materials found on site, which means that secondary phases such as boarding out and plastering can be carried out without having to reposition the manual call points or, where specified, automatic heat and smoke detectors.
“If we do need to move one of the wireless units it only takes seconds. Before, using a wired system, it could have taken up to an hour or more and that’s after we had scheduled for an electrician to be available.”
A wireless fire alarm system comprises manual fire alarm call points that are installed on site in accordance with the project’s Fire Plan. These call points are designed so that the system is interlinked, which means that all floors receive the same audible and visual alert signal, even if the fire is contained to just one of them. No wires are necessary. As each floor is constructed further units are added to create a completely secure wireless mesh network, and alarms can be manually triggered by personnel from any call point. This ability to add or remove units means that personnel in all areas of the site receive the same audible alarm, ensuring that everyone evacuates to a place of safety.
Home Office statistics reveal as many as 104,000 fires occur on construction sites throughout England and Wales each year, with more than 40 per cent of them a result of arson. As a result more sites are choosing to incorporate heat or smoke detectors into the system as they provide automatic cover 24/7. These ensure that the site is protected even when personnel are not present, for example, out of hours, weekends or holidays.
Fire is an ever present danger on construction sites due to the presence of flammable materials, hot work practices as well as a worrying incidence of arson. Because of this, more developers are taking steps to implement effective fire plans and that involves the use of EN 54 compliant wireless fire alarms rather than relying on human intervention, which can be unreliable at best during an emergency.
This article was published in Building Services & Environmental Engineer magazine and the BSEE newsletter in May 2016.