Why do fire-resistant cables need to pass CPR certification?

The EU has enforced the latest Construction Products Regulation (305/2011/EU-CPR) since July 1, 2013. The CPR is stricter than the old CPD Construction Products Directive (89/106/EEC-CPD) and applies to all construction products sold and circulated in the European market. It aims to ensure that construction products' safety, performance and environmental standards (such as cables) are consistent and meet strict fire performance requirements.

In addition to the six basic performance requirements, the regulation requires companies to provide environmental sustainability information for the construction products they produce. Not only that, the new regulation also makes new mandatory requirements for traders, importers distributors, and other links related to the circulation of construction products based on the original constraints on construction product manufacturers, and provides a unified performance evaluation method for construction products entering the EU. By using a common technical language, construction products involving health, safety, and environmental protection are affixed with the CE mark before they can enter the EU market. Ensure the reliability of all construction product performance information.

A. Fire Spread

One of the most crucial factors in determining a cable's fire rating is how quickly and extensively the flames spread across the surface of the cable. Cables that spread flames rapidly can exacerbate fire hazards, potentially igniting nearby materials and increasing the danger to both property and life. Cables with higher CPR ratings exhibit slow or minimal flame propagation, helping to contain the fire and limit its spread.

B. Heat Release

Heat release refers to the amount of heat a cable produces when it burns. The greater the heat released, the faster the fire can escalate, posing significant risks to the building’s structure and occupants. Cables with lower heat release are rated higher on the CPR scale, as they contribute less to the overall heat load in a fire, reducing the chance of fire-related structural damage and providing more time for evacuation.

C. Smoke Production

The volume and toxicity of smoke produced by cables during a fire are essential factors in assessing their safety. Thick, black smoke can obscure visibility, hinder evacuation efforts, and pose serious respiratory risks. Additionally, some cables may release toxic gases when they burn, further endangering lives. Cables with lower smoke production and less harmful emissions are considered safer, especially in public spaces and emergency-critical environments, such as hospitals or transportation systems.

The amount of smoke produced by a burning cable is a critical safety concern, as thick smoke can obscure visibility and hinder evacuation efforts. In confined spaces, like tunnels, basements, or high-rise buildings, dense smoke can lead to panic and severe health risks, particularly for people with respiratory conditions. Cables with low smoke emissions are highly desirable in these environments.

B. Flaming Droplets

Flaming droplets are burning particles or droplets that fall from a cable during a fire. These droplets can ignite other materials, significantly increasing the risk of fire spread. Cables with higher CPR ratings are designed to minimize or prevent the release of flaming droplets. This is especially important in areas where fire safety is paramount, as falling burning particles can cause a chain reaction, igniting combustible materials on the ground or nearby.

C. Acidity of Combustion Gases

When cables burn, they release gases that can be highly corrosive, damaging building structures and electronic systems, and posing long-term safety risks. The acidity of these combustion gases is another critical factor in determining a cable's fire rating. Highly acidic gases, such as hydrogen chloride, can degrade materials and equipment in the vicinity of the fire, making recovery more difficult. Cables with low acidity are considered safer, as they release fewer toxic and corrosive gases during combustion, helping to protect both human health and the integrity of the building. Cables rated with low acidity are more suitable for sensitive environments, such as data centers, hospitals, and other critical infrastructure.

In residential buildings, the focus is typically on ensuring the safety of families, protecting the structure from fire damage, and providing escape routes in case of emergencies. CPR-rated cables, such as those with Cca, B1ca, or Aca ratings, are commonly used in electrical installations, including lighting, power circuits, and home heating systems. These cables are designed to limit fire spread, reducing the risk of fire reaching other parts of the building. In multi-story residential buildings, where evacuation time is critical, cables with low smoke production and flame spread are particularly important to ensure that smoke doesn’t obstruct escape routes or cause panic. For high-rise residential buildings, cables with higher fire performance ratings like Aca or B1ca are typically required in common areas and emergency systems.

B. Commercial Buildings

In commercial buildings, such as offices, shopping malls, hotels, and industrial facilities, the fire safety needs are more complex due to the size, usage, and occupancy load of the buildings. In these settings, CPR-rated cables are used for both general wiring and critical safety systems, including fire alarms, emergency lighting, and evacuation systems. Higher-rated cables are often required in fire escape routes, public areas, stairs, and ventilation shafts, where the potential for fire spread and the need for quick evacuation are higher. For example, cables rated B1ca or Aca might be used in these areas to prevent fire from spreading rapidly through electrical circuits, while Cca or Dca might be sufficient in lower-risk zones. The goal is to ensure that cables in these environments provide reliable service during a fire while preventing the fire from spreading through the building's electrical infrastructure.

In hospitals, the safety of patients, staff, and visitors is the highest priority. Many areas within hospitals, including operating rooms, intensive care units (ICUs), and emergency rooms, require uninterrupted power supply during emergencies. CPR-rated cables are used for critical medical equipment, emergency lighting, fire alarms, and communication systems. Cables with higher fire ratings are necessary in areas where evacuation is difficult, and the failure of emergency systems can result in life-threatening situations. These cables must resist flame spread, reduce smoke emission, and ensure that power and alarm systems continue to operate even during a fire, allowing staff to take swift action and protect patients. Additionally, low acidity and minimal smoke production are essential to avoid exacerbating respiratory conditions or interfering with medical equipment during a fire.

B. Tunnels

Tunnels, whether used for roadways, railways, or subways, present unique fire safety challenges. The confined space and limited ventilation mean that fires can escalate quickly, with smoke and heat posing serious threats to occupants and first responders. In these environments, fire-resistant cables are essential to prevent the rapid spread of fire along electrical wiring, which could endanger lives or hinder emergency response efforts. CPR-rated cables are used in tunnel systems to ensure that vital systems—such as lighting, ventilation, alarms, and communication networks—remain operational in case of a fire. These cables help slow the spread of flames, reduce the amount of smoke produced, and prevent flaming droplets that could ignite nearby materials, ensuring both safety and operational continuity. The ability of CPR-rated cables to continue functioning during an emergency is crucial, as they support fire suppression systems and emergency ventilation, which can significantly improve survival chances in such high-risk environments.