Going Modular
Nov 1, 2002 12:00 PM, Michael Ewald
School construction trends look very strong for the K-12 markets through 2005, and in the higher-education markets through 2010. These projects are going to require millions of feet of electrical wiring and cabling. School administrators should consider modular wiring where applicable. It offers potential for substantial savings, enhanced safety and greater flexibility.
Modular wiring, or cable, is prefabricated wiring used for electrical, telecommunications and building-automation commands. The plans for a school building include details of the electrical layout. Modular wire manufacturers take those drawings and design a complete wiring system down to the outlets and switches.
Once at the jobsite, installation consists of plugging the pieces together. Because the entire project is modularized, wiring components are delivered only as they are required for a specific portion of the building. Sending product as needed to the jobsite minimizes loss of material and reduces sort time by electricians and handling costs.
When contractors bid on an electrical project, they usually are bidding a pipe and wire job, the standard type of wiring. This means most of the electrical system will be built on the project site with basic electrical components and lots of costly skilled labor. Contractors who know that modular wiring will have a significant cost savings often ask schools for a specification deviation so they can install modular wiring.
Because the product is modular, apprentice labor can be used to a greater extent, as opposed to journeyman labor. This will substantially reduce the cost per hour.
The overall cost of the project can be reduced by 25 to 40 percent by using modular wiring instead of the normal pipe and wire. These savings stem from faster installation and less theft of electrical components at the jobsite.
When a contractor proposes modular wiring, school administrators should ask to share in the cost savings. If the electrical portion of a school construction project costs $100,000, splitting the savings with the contractor can save the school as much as $20,000.
Tested for quality
High-quality modular wiring comes with the Underwriters Laboratory (UL) seal. This means the system complies with the National Electrical Code requirements; it has been tested to meet standards established by an independent testing lab. Modular wiring offers consistency from one piece to the next because most factories will test the products for continuity, operation and polarity before the components leave the factory.
Five years is the standard warranty period for modular wiring. By contrast, a pipe and wire system is only as good as the workers installing the system and the local code inspector. The quality can vary greatly from one project to another depending on the skills of the electrician doing the job.
Schools constructed in the 1960s and 1970s used simple three-wire, 120-volt systems. Little thought was given to future growth of the electrical system. Now that computers, closed-circuit TVs and a host of other informational systems are standard, the wiring needed for these services is simply not there.
The cost savings realized with modular wiring systems can be used to install more wires for future growth. Adding those wires during construction can be a good investment that anticipates evolving education delivery methods. For pennies per foot at the time of construction, running an extra pair of wires through a modular wiring system provides for future expansion with minimal upfront cost.
Modular wiring also is safer for the maintenance staff. The systems are designed to simply unplug and plug back together again. There is no guesswork or uncertainty about which wires go where. Most systems are keyed or indexed to prevent dissimilar voltages or uses from plugging together. Outlets and switches can be replaced by simply plugging another switch or outlet into the system. Lower-skilled personnel can perform these tasks, which reduces labor costs.
Because the modular wire system plugs together, as the facility needs changes, the system can be unplugged and moved. Additional pieces are available to reconfigure an existing system. Entire systems can be moved from one building to another, if necessary.
Modular wiring plans prepared by the factory are usually more accurate than “as-built” drawings because the manufactured wiring system allows little deviation. The accuracy of these plans can be important for subsequent additions and changes in the building. Most modular wiring manufacturers will provide up to three sets of plans for their products as part of the purchase price of the system.
Ewald is the director of Electro/Connect and Special Projects for Day-Brite Lighting and serves as a professor in Management of Engineering and Technology at Northcentral University, Prescott, Ariz.
