Self-Grounding Cable Redefines Wiring Practices

Oct 1, 2006 12:00 PM, By Ellen Parson, Managing Editor

With more than 500 condos under contract right now — most of which fall in the $1-million and over category — the staff at Milwaukee-based Roman Electric is always on the lookout for labor savings. So when Project Manager John Perse heard about a new type of MC cable that promised to slash cable installation time by up to 30%, he was all ears. Despite Perse's initial skepticism, the concept seemed revolutionary at first glance. By using a built-in armor ground, this new breakthrough wiring technology would eliminate the need to make up grounds in electrical boxes, outlets, light fixtures, panelboards, and load centers.

After giving the new metal-clad MC^AP(™)(all-purpose) cable from Southwire, Carrollton, Ga., a try about nine months ago, Perse soon became a believer. “My clients want down and dirty pricing,” says Perse. “Anything I can do to value engineer my time and still give them a quality and safe product, I'm there.”

UL listed and NEC compliant, MC^AP cables use the interlocked armor as an equipment grounding conductor — unlike traditional MC cable, which features a grounding conductor underneath the Mylar tape. In its patented design, the armor in MC^AP is equivalent to the green copper ground in conventional MC cables. This is accomplished through interlocked armor and an aluminum grounding/bonding conductor, which are in direct contact throughout the entire cable length. To install, users cut off the aluminum ground flush with the armor, and then attach fittings, listed for use with the cable, to bond the cable to the electrical box.

With more than one-third of his business currently in the condominium market, Perse admits his main motivation behind the decision to use MC^AP was economically driven. “If I'm wiring an apartment building with 180 units with 50 outlets per unit, I'm splicing grounds at every box,” Perse explains. “Even if I save 3 minutes per box, I'm talking serious hours. You do the math.”

However, he maintains he is very satisfied and would not use this new approach if the performance level and quality were not equivalent to comparable MC and AC products.

Living and breathing this product for the past six years, Richard Temblador, director, product development, electrical division at Southwire, actually began new product development on the company's health care facilities (HCF) MC^AP(™) cable variation in 2000. This was while he was working at Alflex, a California-based company Southwire purchased a few years ago, after Temblador's boss challenged him with the task of creating an MC cable for health care facilities that would rival its traditional AC counterpart and meet the NEC grounding requirements in this niche.

Because launching both products required a change to the industry's MC cable standard, Southwire had to clear some high hurdles before gaining industry acceptance, namely getting a UL listing that would allow the interlocked armor to be used as a ground path. “This process was quite an undertaking because UL uses what's called a Standards Technical Panel to review proposed standards changes,” he says. “Because this is made up of a cross-section of the industry, our competitors sit on those panels. So when we were trying to get this approved, some of them were against us. It took quite a bit of work to overcome their negatives, but we did it.”

There were also some issues that arose given the product's unique design. “The fittings that are typically used with MC cable hadn't been used as a ground fault path, so one of the challenges was working with fittings manufacturers to go back out and get all of their fittings tested and specifically listed for use with MC^AP,” Temblador says. “Actually, this task was much easier than I thought thanks to the cooperation of the fittings industry.”

Realizing this new wiring technology also requires a change in mindset for most electricians, one of Temblador's goals is to educate the industry on the significant differences between these new lines and traditional MC and AC cables.

“On HCF MC^AP and MC^AP you get some significant labor savings from the standpoint of simplifying the cable termination process and eliminating the makeup of the grounds in the box, wire nuts, pigtails, and the ground screws,” says Temblador, noting that there's also less volume in the box by taking the grounding conductor makeup out of the equation.

Although this product reduces the number of connections required for grounding, Temblador emphasizes they're not giving up anything in the process. “Because the NEC requirement mandates that installers bond the green copper grounding conductor to the metal box or enclosure, in order to create an effective ground fault path, if something's going to short, it's likely to short the metal,” he says.

For more information and to see an animated demo of the product, visit www.southwire.com.

Product Features

Armor ground path is UL listed, NEC compliant, and equal to a green copper ground
Costs the same as conventional MC, AC, and HCF AC cable
Available in 14 to 10 AWG conductor sizes
Offered in solid or stranded conductors
120V and 277V conductor colors available

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