He currently serves as corporate treasurer, board member, employee stock ownership plan trustee, and marketing committee contributor. He has held numerous leadership roles with the company over the years, including vice-president, chief financial officer, and chief operating officer. That attention to detail and quality could pay dividends at countless cable installations worldwide.Ĭhris Jonnes is an electrical industry veteran, with 50 years of employment with American Polywater. Such seals are engineered for robust performance and long-term integrity. Sealants should be sourced from reputable manufacturers offering products developed, tested, and rated specifically for conduits. Ultimately, the solution is to specify sealing products that meet performance parameters appropriate for the installation, such as closed-cell foams or mechanical seals. Don’t allow the entire system to be threatened by something many view as merely an inconsequential matter: sealing the conduit with a cheap and handy putty. This includes specifying performance-based sealing materials. The solution is to analyze the risks and engineer the system. When seals fail, will the potential damage be caused by worst-case rainfall, ocean surge, noxious gas buildup, animal infestation, etc.? Can those threats be quantified? How much water head or gas pressure must be resisted for realistic integrity? The next step is to assess the source of the threat. Is there any legal liability for any resulting damage? The cost of premature cable failure, compromised electrical apparatus, damaged telecom equipment, ruined carpets and flooring, and even stained drywall as a result of failed duct seals should weigh heavily in this analysis.Ĭonsider, too, the potential cost of service outages.

When water flows into a conduit through a failed seal, what is at risk? Is it more than just the cable (which is obviously expensive enough)? What else is downstream that can be damaged?Īnalysis of the true cost of a cable and conduit installation should extend through the expected lifetime of the system itself, including estimated expenses for repair and replacement. There are no pass/fail criteria, nor any kind of seal testing as part of this classification. They have been tested for fire spread and smoke development as part of a surface burning mark. UL-classified duct seals are typically classified under the surface burning characteristics of general use tapes. You may see the UL mark and believe this duct putty has been tested for performance, but this is not the true situation. How strong is the bond between the putty and conduit wall or cable jacket? How much water head will a duct putty seal hold? How many psi of gas pressure will it resist? The answer to these last two very important questions, unfortunately, is not much (Figure 2).įigure 4: Before and after images of the duct putty after the 100 C test. Here the question becomes: how good is a duct putty seal? Another serious consideration is the performance of an otherwise intact duct putty seal that has not yet sagged or cracked. The development of gaps and cracks over time is only part of the problem. This slow flow manifests itself in sagging over time, which is another way for the material to separate from the top of the conduit wall and break seal integrity (Figure 1). While it may move very slowly, putty does flow under the force of gravity. Sometimes the shrinkage results in cracks in the body of the seal itself which, again, breaks the seal and allows the ingress of water, gas, and other contaminants.Īnother problem is that while the volatile content is still present, the putty is essentially a thick liquid. The shrinking sealant pulls away from conduit walls and/or cable jackets, opening a pathway for water, gas, dirt, insects, snakes, rodents, fire ants, etc. Too often, initial installation results in no seal at all.Įven with adequate installation, when duct putty’s volatile content evaporates, it causes shrinkage that results in gaps. Even a rudimentary seal is difficult to craft. It is very sticky and hard to manipulate. Putty comes with no instructions on how much to use or how to properly seal a conduit.

Electrical uses for duct seal putty