[ Page 7 of 8 ]

By Alex Wilson

Leave no wire behind

A new requirement in the 2002 National Electrical Code (NEC), known as Article 800, specifies that abandoned cables must be removed from plenum spaces. The change was made because of a concern that leaving old cables in place when new ones are added leads to dangerous fuel loading in plenums. Though it’s already being enforced in some jurisdictions, the requirement generally kicks in when a space is remodeled.

Removing old cable during renovations and retrofits raises the issue of lead exposure. Since 1984, most cable jackets have been made with lead-stabilized PVC. As the plasticizer leaches out over time, the jackets become brittle and the lead migrates to the surface, leaving behind dust with a high lead content. This dust, loose in ceiling or floor plenums, can easily reach building occupants or workers removing old cable.

ADVERTISEMENT

Although there seems to be no concerted effort to study or address this potential health hazard, the new NEC requirement forces building owners and occupants to consider potential removal options when cables are first installed. Many owners are now requiring tenants to remove cables once they leave a space; this requirement should lead to more frugal use of cable, the installation of systems that facilitate eventual removal, and better labeling practices for cables in use.

Once old wire and cable is removed, what can be done with it? Copper is a valuable commodity, so old wiring is commonly recycled, but the various additives in wire insulation and jackets raise concerns about incineration, and most of these materials are difficult if not impossible to recycle. Of all the wire insulation and jacketing materials, FEP is the most recyclable, though recycling programs for this material are not known to exist and may not appear any time soon, since the labor involved in identifying and separating it out is substantial.

Wrapping up

Wiring remains a challenge for designers and builders involved in sustainable design. Acceptable alternatives are heavily controlled by codes that focus almost exclusively (in the U.S.) on flame spread and smoke development, with no regard for the toxicity of wire and cable products. Whether this will be considered in fire-safety testing of wire and cable remains uncertain, but it seems clear that the EPA and other agencies will continue researching the safety of halogen-containing insulators.

Perhaps the best news is that better solutions are on the way. “New, innovative materials that are halogen-free and flame retardant will hit the market,” says TURI’s Harriman. “There are significant drivers for their development, even if not from the building industry.”