Bringing yesterday’s buildings into the 21st Century and preserving the interior architecture can be a major challenge; today, any modern building’s functionality is derived from its power, communications and control (PC2) systems. Often, older buildings will be reused for a purpose that was never envisioned when they were designed and built. Even buildings built in the 1960s were only designed to accommodate telephone cabling installed and maintained by the local telephone company. Constructors just a few decades ago could not anticipate the explosion in the use of information technology (IT) by building users, nor were they designed to accommodate the modern life safety, security and building automation systems.
In order to attract tenants, the owners of older and historical buildings must provide the same functionality and amenities that are offered by newer buildings in the same real estate market. Even historical buildings that are used as museums and libraries housing the past are not immune to the need to upgrade because they are competing for patrons and visitors with other similar modern facilities as well as the Internet and other technology-driven alternatives.
Technology can provide the key to preserving the look and feel of historical buildings while making them fully functional in today’s world. Successful adaptive reuse of older buildings will preserve our architectural heritage for future generations, conserve natural resources and help revitalize urban centers. Electrical contractors can help private and public building owners keep their older buildings useful and vibrant for years to come.
Hiding the wires
One of the major challenges faced in a historic preservation project, or even renovating an older building while maintaining its original interior design, is hiding the wires. Modern buildings with drop ceilings make this an easy task, because they were designed knowing that they had to accommodate ductwork, piping and power, and communications and control cabling in order for the building to be functional.
Similarly, walls and columns are often furred out, providing room to conceal raceways and cabling. However, historic buildings typically had no need for ceiling and wall chases; instead, they relied on natural ventilation and daylighting. Load-bearing walls and columns were often brick, stone or timber construction with a plaster covering. Even more recently constructed buildings that incorporated electric lighting and power allowed for very limited chase space and sometimes even embedded the conductors in the wall construction. No consideration was given to building communications and control systems.
High ornate ceilings, architectural moldings and large windows that provide daylighting would be lost, along with the original look of the space, if a drop ceiling was installed. In addition, furring out columns and walls would also change the look and character of the space and should be avoided.
The best solution is to reuse existing raceways and boxes whenever possible by replacing existing conductors. If there is a piping system for gas lighting that is still intact and large enough, it might be possible to use it to feed replacement electric lighting with permission from the local authority having jurisdiction.
Metal-clad cable (Type MC) provides a viable alternative to the installation of either electrical metallic tubing (EMT) or flexible metal conduit (FMC), but only if there is space above the ceiling, inside a wall or down a column that it can be fished. Metal-clad cable is covered by National Electrical Code (NEC) Article 330, and it can be concealed and installed in a variety of locations, including in any type of raceway. If there is concern about the integrity of existing building raceways, or if there is an existing abandoned piping system that would not qualify as a raceway but could be used to route conductors, using metal-clad cable may be a good solution.
In dry locations, Type MC cable can be embedded in plaster finish on brick or other masonry. Metal-clad cable is manufactured in a variety of conductor configurations and sizes and includes an equipment-grounding conductor because its metal sheath is normally not listed as an equipment-grounding conductor per NEC paragraph 250.118(10). Under specific conditions, other cable and raceway systems might be appropriate, such as armored cable (Type AC) covered in NEC Article 320.
In older buildings, it is sometimes not possible to conceal raceways or cables, such as surface metallic and nonmetallic raceways that are addressed in NEC Articles 386 and 388, respectively. These raceway systems have come a long way aesthetically over the years, but they are still surface-mounted and can detract from the building finish and historic context. An alternative to surface raceways where it is possible to channel the wall or column surface might be metal-insulated, metal-sheathed cable (Type MI) that is covered in NEC Article 332.
Type MI cable can be used for feeders or branch circuits, either concealed or exposed, and embedded in plaster or other building materials.
The installation of a raised floor is an alternative that takes advantage of an older building’s high ceilings. This option is best for historical or older buildings that will be used and operated as a fully functional building, but would not be acceptable for historic buildings where it is important that the original floor and molding be seen. A raised floor provides a chase for power, communications and control wiring as well as heating, ventilating and air-conditioning (HVAC) ductwork and piping; it would solve more than just the electrical challenge. In addition, the original floor and molding would be protected from everyday wear and tear by the raised floor, and an open office layout, as well as everyday moves, adds and changes (MACs) can be easily accommodated without compromising or damaging the interior finish.
With the change in floor height, a raised floor does present some architectural challenges, including altering handicapped access and obstructing floor-mounted equipment such as radiators, but if these challenges can be overcome, it simplifies a lot of other PC2 problems.
Nikola Tesla, a Serb-American who may have invented the radio, believed that it was possible to transmit power between generators, motors and other loads without conductors just like a radio. Powering devices without the need for branch-circuit wiring as Tesla envisioned is not feasible today. However, we are able to provide wireless networking to connect users to the building’s local area network (LAN) through wireless access points (WAPs). These WAPs are typically referred to as hot spots and are common in coffee shops, hotels, libraries, schools and other public places. This technology is based on the 802.11 family of standards developed and published by the Institute of Electrical and Electronics Engineers (IEEE). This wireless technology was dubbed wireless fidelity (Wi-Fi) and is being used in historic buildings to connect occupants to the building LAN without the need for copper or optical fiber cabling.
The only drawback for Wi-Fi is the signal attenuation that can occur within old buildings that have thick masonry walls and floors. If Wi-Fi is being considered for a historical or older building, a site survey should be performed to ensure that there is adequate signal strength where it is needed. If there isn’t adequate signal strength, the signal can be boosted, multiple access points can be placed around the building or a combination of both to achieve the needed coverage.
Bluetooth is another wireless technology that can be very useful in historic buildings where multiple devices located within a short distance of one another need to be interconnected. Bluetooth is similar to Wi-Fi, but it is slower and not designed for high-speed data transfer. Bluetooth-enabled devices can find one another and interact without a physical connection, making it ideal for interconnecting printers and other devices.
Zigbee is a new technology that does not have the speed or bandwidth of Wi-Fi or Bluetooth, but is designed for wireless building controls. ZigBee is based on IEEE Standard 802.15.4 and creates a self-organizing wireless network where any ZigBee-compliant device introduced into the environment is automatically incorporated into the network as a node. A number of manufacturers are currently developing devices that incorporate this technology, including switches, thermostats and other common monitoring and control devices. ZigBee devices are battery powered, which means that they do not need any interconnecting wiring, making them ideal for historic buildings. These devices remain dormant until they are activated by an incoming signal, so their batteries can last for months or even years without replacement.
Devices such as telephone sets using voice over Internet protocol (VoIP), security surveillance equipment such as cameras and access control devices, wireless network access points, and other sensing and signaling equipment have always required both a power and communications connection. Today, IEEE Standard 802.3af defines the requirements for providing power to equipment connected to a structured cabling system and is referred to as power over Ethernet (PoE).
Providing power directly to network devices via the network’s standard Category 5e or 6 unshielded twisted pair (UTP) copper cabling not only reduces installation costs and can provide more reliable power than local branch circuits, but also eliminates the need for a 120-volt branch circuit at the equipment, which can be very helpful in a historic or older building. PoE can be accomplished either by using Ethernet switches with the power source built in or by midspan devices also known as power hubs that are installed between the Ethernet switch and the device being powered. Structured cabling systems and PoE are typically classified as Class 2 power-limited circuits, which means that they can be installed in accordance with NEC Article 725 without raceway, but this should be verified for the specific equipment being used.
Soon there may be a 120-volt receptacle available but no way to get network cabling or an outlet at the location. A solution to this would be to use the branch circuit for power as well as Ethernet, which is the reverse of PoE as discussed above. This can be accomplished by using a powerline Ethernet adapter that just plugs into a receptacle at the switch or server location and another adaptor at the location where a network connection is needed. Using a powerline Ethernet adapter will eliminate the need for UTP copper or optical fiber horizontal cabling and may work in locations where it is not possible to use a wireless access point. Regardless of the technology used, electrical contractors most likely will be called upon to upgrade historic buildings. EC
This article is the result of a research project investigating the emerging IBS market for the electrical contractor sponsored by ELECTRI International Inc. (EI). The author thanks EI for its support.
Glavinich is an associate professor in the Department of Civil, Environmental and Architectural Engineering at The University of Kansas. He can be reached at 785.864.3435 or firstname.lastname@example.org.