Direct Burial Ethernet Cable: Gel Filled vs. Waterproof Tape

Direct Burial Ethernet Cable: Gel Filled vs. Waterproof Tape

Written by Don Schultz, trueCABLE Technical Sales Representative & Fluke Networks Certified Technician 

If the question about gel-filled and waterproof-tape, direct-burial Ethernet cable has been keeping you up at night, or if there is a bet involving money about which is “better”, you have come to the right place! Read on, make money, and get your rest.

 Icky-pic really is quite icky. It is also the common name used for petroleum based gel-filled direct burial cabling. Up until a few years ago this was the common way of making sure water did not get into direct burial cabling.

 Waterproof tape is not icky, at least not as icky as icky-pic. Now, please say that fifteen times forwards and then backward. If anyone in earshot asks if you have finally gone and “lost it”, just point them to this article.

Waterproof tape is becoming increasingly common and has replaced the traditional icky-pic method for all but the most extreme scenarios.

So, which one is better? First, let’s go over how each type works and what makes it “waterproof.”


  • filled with petroleum based gel which is thick, sticky, and quite icky.
  • requires solvents to clean up, such as charcoal lighter fluid or paint thinner.
  • just about impossible to get off of your hands unless you are willing to wash them with charcoal lighter fluid or paint thinner.
  • must be removed from the copper conductors prior to termination, or the termination will be fouled and potentially not work. At the same time, terminations must be thoroughly sealed as the petroleum gel can leak from the cable ends.
  • an electrical insulator. The gel does not convey an electric current.
  • an environmental hazard.
  • extremely flammable. You should not use icky-pic indoors. Underwriter’s Laboratories (UL) specifies icky-pic must stop 50 feet before entering into a building. At this point, the icky-pic cable is terminated. Continuing on to the building a less offensive outdoor rated cable is run into the structure.
  • non-hygroscopic, protecting against water getting past it to the copper conductors.
  • not protective of the copper conductors from mechanical damage.

Waterproof tape

  • dry to the touch, but ready to be activated by water.
  • tough and protective of the copper conductors from mechanical damage. The waterproof tape inside trueCABLE’s Direct Burial cable is such that the average person cannot rip it, even after cutting the edge first and trying to remove it from the cable end, like you can do with aluminum foil shielding. Get out the flush cutters, you will need them.
  • requires no cleanup and is not a fire hazard.
  • electrically conductive. The super absorbent polymer is activated by water, and water is electrically conductive. See the test below for more.
  • will not allow liquid to reach the copper conductors. Instead, the polymer will activate, the cloth tape will swell, and gelatinous polymer will migrate around the conductors thereby sealing it off. See below for more detail.
  • not environmentally offensive or dangerous. The super absorbent polymer is the same type used in baby diapers and feminine hygiene products.

Recommendations for Installation Environments

  • Install waterproof tape direct burial cable anywhere outside, whether underground or in open air runs. For commercial installations, it may run indoors up to 50 feet (per the National Electric Code 800.113), but should not run into the plenum space.  For residential installations CMX may be used as indoor/outdoor cable assuming the following rules are obeyed:
    • Cable thickness (OD) or outside diameter may not exceed 0.25”
    • The residence is restricted in size to a single family or duplex dwelling
  • Install icky-pic in extreme scenarios such as below lake beds, in/under swamps, under rivers, or any other situation where the risk of fire is low and the risk of copper conductor damage from mechanical means is even lower. There may be EPA (Environmental Protection Agency) guidelines for these areas, so research carefully. Needless to say, this cable should not be run alongside a building or in open air scenarios. If the cable should set ablaze, the result will be something similar to napalm dropping from the sky as the burning globs of petroleum gel drop onto the ground, lighting up anything flammable in the process.


You know that this blog would not be fun if some tests with pictures weren’t conducted. This is the type of topic that just begs for photos. So, here we go:

 First up, what does the cloth carrier look like dry and what happens when it gets wet? The gelatinous polymer was slippery but not sticky. It had no odor. Washing off with water was easy.

Outdoor Ethernet Cable Dry Waterproof tape

Outdoor Ethernet Cable Wet Waterproof tape

Second, is the activated polymer conductive? Indeed. The handy flashlight test always works:

Outdoor Ethernet Cable Waterproof tape conductive test

Third, the outer jacket was slashed with a razor knife simulating a simple glancing cut. The shield was specifically breached, but not the waterproof tape. The cable was then placed in a water filled container for 24 hours. At the conclusion of the test, the cable jacket was sliced off length-wise, the shield unwrapped, and the waterproof tape was peeled downward like peeling a banana.

Outdoor Ethernet Cable Cable Breach

Cable breach!

Outdoor Ethernet Cable 24 hour soak

24 hour cable soak. The ends were kept out of the water.

Outdoor Ethernet Cable Waterproof tape internal assembly

The jacket and shield removed. This reveals the interior assembly. What you cannot see in the picture is the waterproof tape is saturated and fully activated. The water did migrate up the tape. Liquid water droplets were apparent under the cable jacket plus above and below the foil shield.

Outdoor Ethernet Cable Internal Assembly after test

The waterproof tape, peeled off in one piece. If you look closely, the spline has been coated in the immediate breach area with the gelatinous polymer.

 Outdoor Ethernet Cable Internal Assembly after test no. 2

The copper conductor pairs were separated from the spline and rapped on the table to find out if any liquid water was present. It was not. Only gelatinous polymer was present.

So there you have it! Now, if you have any bets you placed on this, and wish to send along some cash if you want…*wink*

In all seriousness, the waterproof tape method is the way to go for direct burial cable. Not only does the tape perform as advertised, but the tape functions as another layer of defense under the already tough cable jacket. To cut a conductor on this cable, while installed, would require a shovel or some other extreme means. Conversely, icky-pic might be great at keeping water out but does nothing to protect the copper conductors. If the copper conductors are damaged, the cable must be replaced no matter what.


 trueCABLE presents the information on our website, including the “Cable Academy” blog and live chat support, as a service to our customers and other visitors to our website subject to our website terms and conditions. While the information on this website is about data networking and electrical issues, it is not professional advice and any reliance on such material is at your own risk.

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