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Fixed Wireless Equipment

Outdoor Cable

It's important to keep water out of the power cables for your outdoor wireless radios, but some solutions may not work as suggested.

[August 3, 2006]

On the ISP-Wireless list in July, RK asked:

I'm curious. What outdoor cat5 type does everyone use? Currently we are using Belden 7919A which is an outdoor, UV resistant, non-gel-filled, shielded cat5 cable. I've heard that gel-filled should be used, but I'm not sure as to the benefits of gel-filled cable. What about in 25-pair outdoor cables?

[DF replied] "I'm sure there are real uses that I'm not aware of, but in the past, the argument we were given for gel-filled was just in case the cable was hit with a shovel or something, but it didn't actually damage the copper itself... the gel would seep into the break in the outer layer and seal it off.

In reality, I'm not sure how many cable cuts only make it in that far...a shovel or a backhoe never stops at the protective layer of a cable.

The real downside was crimping these cables... especially for less experienced crimpers... if you didn't clean off the gel with rubbing alcohol you'd better get all the strands into your plug quickly, or the gel will harden and you won't get anything in there.

Basically, in my experience, they were a frustration. Burial-grade STP without the gel is probably cheaper and easier to work with in the long run."

[ZT added] "We use (basically) the same stuff that you do. We used to use gel-filled, but had to go away from it because of overall cost (no local suppliers). I've been squawking at the bill payers to get the gel-filled in for a while now because the non-gel-filled seems to wick water down it and right into the POE injector. We've had some where the installer obviously nicked the cable with a staple, and we've had some that wicked from the radio end of the cable (where the installer didn't cut the cotton pull line off when they made the end). From what I've read and have been told, the gel-filled won't do that, ever. I could be wrong, though."

[TR replied] "With gel-filled, we have had water drip through 150 feet of cable mostly laid horizontal exempt for a ten footvertical drop at the end and a 10 ft vertical drop at the beginning. We had a fake sense of security that gel would not let the water drip, and mounted our switch with the jacks facing up. Big mistake.

Water dripped into the jacks and short circuited the switch. Gel helps reduce water intrusion when the outer casing gets nicked. But if water can get in through the end, it may still be able to [cause problems]. In our case, the weight of the cable (and possibly movement of cable) allowed the outer sheathing to slide down a bit, allowing it to be below the rubber seal on the Trango Entry way by a quarter of an inch, where water could drip in."

—End