Is There Such a Thing as Direct Burial RG 213?
As a cable design engineer, I have had concern for ads I have seen for “Buriable RG-213”, for two reasons. First, per the Mil Spec, RG-213 utilizes a PVC type IIA jacket. The IIA jackets are also termed “NCV” (non-contaminating vinyl). Most suppliers sell this Mil Spec or equal in part because a IIA jacket does not have plasticizers that can migrate into the dielectric causing significant electrical changes in the cable. The “non-contaminating” refers to these plasticizers that adversely affect the cable dielectric.
Secondly, I know all the good cable manufacturers in the United States and there is only one manufacturer that is now doing a form of PVC jacket which can be rated as direct burial. However, the factory is unable to produce that jacket as a IIA, NCV, in addition to being buriable. Yet I have seen at least one ad that claims a RG213 as NCV and buriable.
As we all know, a high percent- age of cable is at some point in the installation subject to the sun. Where the cable is subjected to the sun, you want it to be an NCV type. Equally important is that buried PVC cable can also leach plasticizers into the dielectric if not NCV.
For some reason there are a few distributors out there who claim
their RG-213 is buriable. When I talked to one recently, he agreed to check with his manufacturer, only to find out that it was PVC IIA jacket, not buriable. The distributor was ethical enough to call me back and indicate his apology and that he was pulling the ads.
PVC of any type is buriable for a limited period of time before the electrical and moisture proof qualities start to degenerate. Note that I say “moisture proof”, not “waterproof”. There are no PVC coax jackets on the market today that are “waterproof.”
To solve a customer’s (and your) concern for burying, either use our Bury-FLEX ® (my design over 10 years ago and used by NASA, Lockheed Martin, etc) or put any PVC jacketed cables (213, 214, 8X, 59, 6, etc) in a conduit. But don’t let water accumulate in the conduit. Bury-FLEX ® can be laid in water, coiled around crank up towers and is highly rodent resistant, unlike PVC jackets.
If any questions, please feel free to contact me.
-Steve Davis, K1PEK, DAVIS RF Co. sdavis@DavisRF.com