General Wiring Guidelines
Design for easy access. Install wiring in readily accessible wiring chases to simplify future modifications. Minimize wiring runs. Reduce material use by installing high-capacity runs to local hubs rather than connecting each workstation directly to a central hub. Local hubs can connect to workstations via wireless or short wired connections. Avoid wiring in exterior walls. Especially in residential buildings, limit wiring runs and receptacle placement in exterior walls. Such installations interfere with insulation and can result in significant air leakage. Avoid the need for plenum-rated and limited combustion cable. Run data cable in metal conduit, sealed wiring chases, or cellular raceways of concrete decking to avoid the need for highly flame-resistant cable. Go wireless. Use wireless data connections instead of hard-wired ones for maximum flexibility and minimum material use. Wireless connections may be usable in some local areas, even if they are not usable building-wide. Don’t overwire. Design for future wiring needs, but avoid installing wires unless there is an immediate need for them. Future needs are hard to predict. Label wires. Label all wires carefully at both ends to ensure that they will be utilized effectively. Design for future removal. Design wiring installations so that wire can be easily removed when not in use. Minimize EMF. Rely on “prudent avoidance” strategies to minimize exposure of building occupants to electromagnetic fields. See EBN Vol. 3, No. 2 for recommended practices.Wiring Specifications
Plan for future needs. Install voice-data-video (VDV) cable that can serve upgraded networks—with faster data transfer speeds than your current network—so that the cable will not become obsolete as quickly. Eliminate use of lead stabilizers in wire insulation and jacketing. With PVC wire and cable, specify lead-free product that does not contain lead stabilizers. Some PVC wire insulation and jacketing are comprised of 5–10% lead by weight. Do not install lead-stabilized cable loose in plenums. To keep lead dust out of the building air, cable that is stabilized with lead—including most plenum-rated cable—should be installed in metal conduit and not directly exposed to the conditioned air circulating through a ceiling or floor plenum. Specify halogen-free wire and cable. Wherever possible, specify wire and cable insulation and jacketing that do not contain halogens. This includes PVC, chlorinated polyethylene, FEP, and products containing brominated flame retardants. Specify heavy-metal-free wire and cable. Even wire and cable that is free of lead stabilizers is often pigmented with lead, cadmium, chromium, and other heavy metals. Specify cable that is free of all heavy metals, including pigments. Use fiber-optic cable where possible. Fiber-optic cable is widely used for carrying voice and data signals. Because light rather than electric current is being carried and because the primary component is glass, less insulation and jacketing are required than for copper wiring. It may be possible to run fiber-optic trunk lines to smaller copper distribution lines and thus reduce total insulated cable use.Wiring Removal
Remove old cable. Whenever new cable is being installed in a building, remove any old cable that is not being used or will not be usable in the future, as per the 2002 revisions to the National Electrical Code. Follow proper safety precautions in removing old cable. Old cable contains high levels of lead dust, and significant care must be taken during removal. Ensure that workers wear the proper respirators for lead dust, and seal removed cable in plastic bags. Recycle old cable. Deliver old cable removed from buildings to facilities where the cable is properly recycled. NEVER burn old cable to recover copper.
