ARCHIVED - Keeping fire at bay
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February 01, 2011— Ottawa, Ontario
Homes and buildings built to meet the 2010 National Building Code of Canada (NBC) will better protect Canadians from fire.
“Many changes have been made in past code editions to improve fire safety for building occupants, including changes to fire alarm requirements that have contributed to reducing fire-related fatalities in houses,” says Philip Rizcallah, a senior technical officer with the Canadian Codes Centre at NRC. “The 2010 NBC brings further improvements to these code provisions by taking into account new knowledge and new technologies.”
Early smoke alarms were battery operated. But people often failed to replace dead batteries, making the alarms useless. To address this, the 2005 Code required that all alarms be hardwired (i.e., permanently connected to an electrical circuit with no disconnection switch). However, too many people who had simply burned toast or boiled a kettle near the alarm were disconnecting the wire to stop the noise, and then failing to reconnect it.
“We needed a mechanism to discourage people from tampering with the wiring,” says Rizcallah. “What’s more, hardwired alarms don’t work during power failures. That’s when the risk of fire is greatest since people rely on candles, fireplaces and propane gas stoves.”
The 2010 Code addresses these situations. “Homes built to the new Code must have hardwired smoke alarms with a ‘hush’ button and a 9-volt battery backup that kicks in during power failures,” explains Rizcallah. The new Code also requires a smoke alarm in all sleeping quarters as well as adjoining hallways.
Rousing sleeping children
A 2004 Australian study reported that 81 percent of 114 fire fatalities occurred at night and 86 percent of the victims were sleeping. It found that children, the elderly and people who are sleep deprived, or under the influence of alcohol or drugs, are far more likely to sleep through a beeping alarm. Children are particularly at risk because they are deeper sleepers, making them less aware of their environment.
The same study also showed that an irregular pattern of beeping or a voice relay could rouse more people from sleep than the standard beep. For children, a pre-recorded female voice urging, “Fire, fire, get out!” dramatically increased the wakeup rate.
“The 2010 Code incorporates these findings,” says Rizcallah. “Previous editions required smoke alarms to emit sound at a given decibel level, but didn’t specify the kind of signal. Now, alarms must relay a voice message or meet a given temporal pattern — three short beeps followed by a longer break. The break interrupts your brain wave and wakes you up.”
Voice communication systems
Studies have shown that a mandatory voice communication system would increase safety when fire alarms go off in large retail stores.
“So-called ‘Big Box’ stores often sell large amounts of highly flammable materials ranging from styrofoam and fertilizer to gasoline and tires,” says Rizcallah. “In one case in the U.S., someone brought in a lawnmower for repairs and parked it next to fertilizer. The oil from the lawnmower leaked, igniting the fertilizer. In no time, they lost the whole store.”
Other research has shown that when shoppers hear a fire alarm, most don’t leave the store. When people have a cart full of merchandise, they want to complete their shopping, assuming there is no real emergency. Often cashiers worsen the situation by continuing to work. In a real emergency, people have limited time to get out, yet they don’t always move as quickly as they should.
“This is why the 2010 Building Code requires voice communication in any building with a design occupant load of more than 1000 people,” says Rizcallah. “The voice communication system will allow either the fire department or trained staff to broadcast a message giving clear evacuation instructions. An example could be: ‘This is not a drill. Please leave your cart and move quickly to the nearest exit.’” The new Code also sets out voice intelligibility criteria to ensure that people can easily understand the message.
The 2010 National Building Code
The 2010 National Building Code is one of three national model construction codes recently published by NRC, the other two being the National Fire Code and the National Plumbing Code. These model codes are developed through broad-based consultation and consensus among all sectors of the construction community — regulatory authorities, designers, builders, suppliers, researchers and general public.
These codes are model codes only, given that the provinces and territories have jurisdiction over construction. However, almost all buildings in Canada are built to regulations that are based on the national model codes. Most provinces/territories adopt the national model codes as is or with very few changes, while others adapt them to suit regional needs before publishing them as their own codes. Learn more about the codes.
- Information on the 2010 codes
- Important code changes for 2010
- Keeping fires under one roof
- Keeping radon out of Canadian homes
- National construction codes and guides
- Why building occupants ignore fire alarms
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