Little-Known Installation Risk Can Mean Big Problems
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Little-Known Installation Risk Can Mean Big Problems

Nick McLain
Feb 14, 2013

A few weeks ago, I brought you a story about a relatively unknown danger, a form of asbestos insulation called vermiculite.

I’m back today with a heads-up on another issue: the potential damage that can result when network cable bundles come into prolonged contact with PVC (polyvinyl chloride) and CPVC (chlorinated polyvinyl chloride).

PVC pipe and low voltage cables

The most common use of PVC and CPVC pipes are in structural fire sprinkler or hot/cold potable water systems. According to The Vinyl Institute, a vinyl industry trade group, PVC accounts for 66 percent of piping applications in the water distribution market and 75 percent in the sanitary sewer market in the U.S. Fire sprinkler pipes are often identified by an orange color, while plumbing pipes are usually white. CPVC is different from PVC because of its higher chlorine content, which enables it be more ductile.

To get more information, I reached out to two plastics experts — Dr. Duane Priddy, CEO of Plastic Expert Group, and Clint Cowen, president of CPC Plastics — to get their take. Both agreed it is an under-reported but legitimately important factor to be aware of on the job. “It is something that is relatively unknown by both plumbers and electricians and those in the multimedia realm,” Cowen says. “But it’s absolutely an issue, especially with the use of CPVC and PVC growing every year.”

Cowen said he was currently doing case analysis on the very situation — network cables causing possible CPVC pipe damage — which I called him about. He periodically is asked to evaluate and subsequently testify about these problems, as is Priddy.

The reason for the damage, Priddy says, is the phthalate plasticizers often used in the flexible cables (he particularly cited Ethernet cables) coming into prolonged contact with the pipes, usually putting stress on the pipe by being tied to it, wrapped around it or resting on it. As the name implies, plasticizers are primarily used in plastics to offer greater flexibility and durability. When the PVC piping absorbs the plasticizers from adjacent cables, the pipes can weaken, potentially leading to leaks and even ruptures.

“Often times I’ve seen five or six Cat5 cables bundled together with a nylon tie, draped along the fire sprinkler pipes, and with the weight put on the pipe, it sucks the plasticizer from the cables and blisters pretty quickly,” Priddy says. “CPVC and PVC have a high affinity for these plasticizers. As it absorbs the plasticizer, the rigid pipes swell and soften and lose its mechanical rigidity to hold back water pressure.”

Many plastics manufacturers recognize the potential problem and provide explicit warnings for their customers, either in technical bulletins or other communication channels. For example, on its website, the chemical company Lubrizol states:

Direct contact with flexible wire and cable that utilize insulation containing plasticizers is not recommended. Section 334.30 of the National Electric Code (2002 Edition) requires wire and cable to be secured by staples, cable ties, straps, or hangers. Air ducts, pipes and ceiling grid are not acceptable supports for wire and cable.

Interestingly, PVC is the most common substance used in the outer jacketing of cables, although it differs from the PVC used in the rigid pipes in that the piping PVC typically contains no plasticizers.

Alice Albrinck, senior materials development engineer with Belden, a major cable manufacturer, says plasticized PVC cable jacketing is still the norm in the U.S., despite “mild” pressure from environmental groups and from those looking to move away from plasticizers that migrate easily. “There are various reasons for choosing PVC [for jacketing],” Albrinck says. “They are very easy to modify to meet a variety of requirements, they have good fire retardancy, and they are a very versatile material at a relatively low cost, which is good for our customers.”

Priddy says PEX (cross-linked polyethylene) is becoming a viable alternative to PVC and CPVC pipes in new home builds, with the added benefit, he says, of it being much less likely to fail if it comes into contact with network cables. But PVC and CPVC are still most common.

Ken Erdmann, CEDIA Lifetime Achievement Award winner and owner of Erdmann Electric in Springville, Utah, says the issue is real and “kind of a big deal.” In his experience, CPVC is more susceptible to damage than PVC.

Although some may view it as a time-saver to run wires in the holes drilled earlier by the plumbers or even zip-tie cable bundles to pipes, Erdmann cautions to adhere to the National Electric Code and do it the right way, drilling your own holes and strapping the cables to the structure itself with the proper materials.

“We try to be fairly religious about that,” Erdmann says. If you’re installing wires across CPVC or any pipe, he advises leaving a minimum of 1-inch separation between the pipe and cables. Furthermore, he recommends arranging cables in a way so that if insulation is installed in the area at a later time, the cables won’t press in the direction of the pipes.

Ric Johnson, a former chairman of the CEDIA-NAHB (National Association of Home Builders) Partnership and president and CEO of Right at Home Technologies in Mason, Ohio, also sees the issue from time to time – more so on the commercial side than residential, but he agrees with Erdmann. “With proper installation best practices, this problem is completely eliminated,” Johnson says.



About Nick McLain
Nick McLain is CEDIA's Technical Journalist. He can be reached at nmclain@cedia.org.

3 Comments

  1. 3 Thomas Oliver 14 Nov
    Is there any known negative consequence or concern with using plastic zip ties to strap PEX water distribution piping to PVC drain, waste & vent piping?
  2. 2 Natalie Ewan 12 May
    In my experience we typically use a piece of Roxall type insulation as a barrier between the pipe and the wire. Would you consider this to be efficient?
  3. 1 Alexis Sciandra 07 Aug
    What do you suggest to maintain the " minimum of 1-inch separation" between the pipe and cables? A piece of wood? 
     

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CEDIA blog posts are intended to provide general information and should not be regarded as legal opinions or advice.

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