FEATURE ELECTRICAL & ELECTRONICS
Chris Lloyd, managing director at Spelsberg UK, looks into the advantages of fire-resistant,
surface-mounted enclosures for
protecting electrical connections
WKE Lifeline cable junction and connection box
PROTECT COMPONENTS WITH POLYCARBONATE ENCLOSURES
S
afety systems need to continue operating in the event of a building fire. In addition to warning alarms, lighting must highlight
the route to a safe exit; smoke and heat extraction systems might be needed; and water booster systems to supply extinguishers. Furthermore, dedicated elevators might need to safely transport fire crews. All these systems need electrical power
and protection of their supply during a blaze, potentially for an hour or more after a fire has taken hold. While cable junctions and distribution boards have historically been designed and embedded within concrete protection to achieve this, installing electrical connections within fire- protected enclosures mounted directly onto walls can offer equivalent – or even greater – protection.
FIRE AND HEAT DAMAGE The protection concrete provides to embedded electrical junctions depends on its thickness, and whether additional insulating materials are used. In addition, embedded electrical junctions might not sufficiently contain a fire should an electrical failure occur inside a concrete wall. In a case like this, the fire could spread through cavities or reach flammable materials. In the event of any high temperatures, concrete
can also conduct heat and retain it over an extended duration, sufficient to degrade or damage any enclosed electrical connections. Embedded electrical connections could also be exposed to hidden moisture or damp conditions, which could corrode and damage junctions. But, the only way to make a visual check is to drill in or completely expose the electrical junction.
FIRE-RESISTANT ENCLOSURES Enclosures manufactured from specially
treated polycarbonate, which are resistant to flame and heat, can protect electrical junctions in the event of a fire. As polycarbonate is non-conductive during
fire or heat exposure, the enclosures also prevent the risk of short circuit. Protection features such as ceramic terminal blocks inside the enclosure, which are resistant to high heat, also help to protect the connections. Combining these features in a surface-
mounted enclosure can ensure electrical integrity for up to 90 minutes, according to the E30-E90 electrical functional integrity standard. This testing and recognition are the hallmark for fire- and heat-protected enclosures like the Spelsberg WKE Lifeline cable junction and connection box. However, an enclosure designed specifically for
fire protection and wall mounting also needs to form a barrier against more than flame and heat. These special junction boxes need to withstand water ingress from sprinkler systems and high- pressure hoses, so an IP66 rating is also key. An IK08 impact protection rating should also apply to defend electrical connections from force, which is another advantage of designing with high-strength polycarbonate.
ACCESS While appropriately designed, externally fitted enclosures can provide sufficient fire defence, easy access
46 DESIGN SOLUTIONS DECEMBER/JANUARY 2025
enables frequent inspection. For example, the Spelsberg WKE fire protection box can be rapidly accessed by maintenance and safety teams via four screws positioned in the enclosure cover. This lid is held in place by a cover retainer lanyard to prevent loss during inspection, while unauthorised access can be prevented thanks to a safety seal. Just like a standard junction box, wall-
mounted, fire-resistant enclosures can be installed wherever required, without needing to make precise design plans in advance. In the case of the Spelsberg WKE, the enclosure can be quickly mounted in situ by two external lugs that can be rotated 90 degrees. Inside the box, the terminal block can also be adjusted through three positions, including 0, 45 and 90 degrees, and cables can be quickly and securely inserted with additional metric cable glands.
THE RIGHT ADVICE It’s always a good idea to have specialist support when specifying an enclosure for fire protection. This could range from advising on the right type of enclosure to meet the electrical connection needs of the installation, whether that’s a high-rise block of flats or an underground railway, as well as ensuring that the required safety compliance is met for the environment. Wall-mounted enclosures that meet E30-
E90 fire and heat resistance, and also enable rapid installation and maintenance access, are an ideal solution.
Spelsberg UK
https://www.spelsberg.co.uk/1/
Fire protection solutions from Spelsberg
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