Paul Allen from power distribution specialist, CMD, discusses the challenges of electrical distribution network installations in shallow floor voids and listed buildings

ver the past 30 years, the amount of tech used in commercial buildings on a day-to- day basis has increased dramatically, which means more sockets are required across the floor plate, with sufficient capacity for resilience and futureproofing. In new builds, floor voids are usually designed with sufficient capacity for the level of services required. In existing buildings, constructed before technology became such an integral part of the way we live and work, capacity in the floor void can be more challenging. It’s an issue that electrical specifiers and contractors face repeatedly when planning the electrical infrastructure for commercial buildings. A busbar powertrack system is most commonly the solution of choice, because it offers speed and ease of use with plug and play installation and plenty of flexibility for reconfiguration, additional tap-offs on the network and parallel UPS distribution. At 47mm, the CMD Betatrak powertrack system is suitable for most floor voids, but additional clearance is required to access tap- offs for maintenance or reconfiguration. While this does not present any challenges for


most new build properties, for older buildings with more restricted floor voids or inconsistent void clearance, there is often insufficient space for a functional powertrack system. Often, specifiers assume that this leaves them with a choice of two onerous options: either to raise the floor and increase the void, or to opt for a hard wired electrical network. Both of these choices would add time to the programme and raising the floor could compromise headroom and heritage features.

That’s why there is an increasing appetite for a third option for refurbishment and heritage electrical distribution installations, power hub systems.


Designed to offer comparable plug and play ease and speed of installation along with the flexibility and futureproofing benefits of powertrack, power hub systems are an idea alternative where space is limited. The CMD 32A Power Hub has been specifically designed for buildings where a conventional powertrack system cannot be installed due to lack of void depth or obstacles in the void. It is also ideal for use in buildings where the slab is uneven, which would result in lengths of powertrack lying a different heights or angles, preventing consistent connections. With a height of just 38mm and tap-


offs to the side of each unit rather than above, the CMD Power Hub is suitable for use in shallow and undulating floor voids and offers ease of installation, ease of maintenance, future flexibility and compliance. Power hub systems combine compact hub units with flexible metal conduits or ‘umbilicals’, which connect the hubs together to create the electrical distribution network. The metal flexible conduits provide cables with mechanical protection, allowing compliance with Wiring Regulation 543.7 “Earthing requirements for the installation of equipment having high protective conductor currents”. They also protect cables from dirt ingress and rodents, ensuring a similar level of resilience to powertrack systems and ensuring that the electrical distribution system offers a low maintenance, fit and forget solution CMD Power Hubs are available in 4-way and 6- way units, which can be wired in a series circuit in the required configuration. Tap-offs are made to the side of the power hub unit, using BS EN 61535 compliant connectors in a metal housing to ensure a secure and safe tap-off connection. A choice of tap-off units allows electrical supply to be routed to the required locations, regardless of how densely populated the floorplate will be, while minimising the number of hub units required, thereby keeping costs and installation time down, reducing maintenance and optimising space in the void.

Additional hub units or tap-offs to existing units can be retrofitted to the installation at any time, providing the flexibility needed in contemporary commercial buildings for changing occupier requirements, change of occupier or chance of use. No additional space is required for plugging in or unplugging tap- offs and multiple power hubs can be configured together on a single circuit.

that contractors must constantly overcome. A power hub system provides an ideal solution, with rapid, cost-effective plug and play installation for a wide variety of projects. For example, for a recent installation at a film and TV production company, the CMD power hub was found to offer the most compact unit to meet the needs of a shallow floor void and 900 units were installed to provide the flexible distribution network in an environment where needs will continue to change. In another example of how power hubs can overcome architectural challenges, CMD’s power hub system has recently been installed in the ceiling void to service the void-free concrete floor of the level above. Once again, the compact units and potential for reconfiguration were key benefits of using a power hub system.

A power hub is not always the most appropriate specification, but, where powertrack is not suitable, a power hub is often the best alternative.



Finding the right solution to match the needs of the building and the client, while working within a tight programme are challenges


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