CUTTING HAZARDOUS LOCATION CABLE COST
Alternatives to conduit can cut installed cable costs in Class I hazardous locations
- Published in Southwire's Power Cable Update newsletter in March 1998
- Reprint permission granted
For years, conductors in conduit have been standard wiring in Class 1, Division I hazardous locations. Conduit gives good protection but it's expensive and time-consuming to install. Now there's a lower cost alternative: cables with seamless aluminum armor. "Cutting, bending and fitting conduit is a tedious job," says Bobby Gentry, product development manager. "Pulling conductors creates many opportunities for cable damage. You can install continuous corrugated aluminum armor cable in less time than it takes to hang empty conduit, and with far less risk of cable damage."
Seamless Sheath Seals Cable
The continuous corrugated aluminum armor is completely impervious to liquids and vapors. jacket options provide high resistance to chemical corrosion and LTV protection.
Section 501-4(a) of the 1996 National Electrical Code (NEC) allows this type of construction in Class 1, Division I locations where hazardous liquids or vapors may be present during normal operations. Underwriters Laboratories' (UL) HL (hazardous location) listing, defined in standard UL-2225, rates continuous corrugated aluminum armor cable for these applications.
"Southwire's type MC-HL ARMOR-X' cable products meet the tough impact- and crush-resistance requirements of the new standard," says Gentry. Type MC-HL ARMOR-X is available in 600V and MV-105 constructions, with conductors up to 500kcmil.
Interlocked Armor May Work In Division 2
"In Class 1, Division 2 locations, you may be able to save even more by using a jacketed interlocked-armor cable such as Southwire's Aluminum MC," Gentry says. In Division 2 applications, the hazardous vapor or liquid is only present in abnormal conditions. NEC Section 501-4(b) describes the cable requirements.
"One way to view the distinction is to look at where the gas/vapor barrier function takes place," says Gentry. "In Division 1, the metallic sheath is expected to provide the barrier. In Division 2, it's sufficient to have a polymeric outer sheath as the vapor barrier."
Gentry adds, "Whichever you use, be sure your terminations and fittings are listed for the application. It's important to keep hazardous vapors and liquids from migrating through the cable system. If there's any question, check with the hardware manufacturer." |
