How to Waterproof Electrical Connections

Electronics and water do not generally mix, but sometimes you need to have electrical connections in places that can get exposed to water, especially when working in areas near water or in places where it rains a lot.

You do not want to have exposed contacts because this can cause corrosion or short out a circuit. This can cause an inconvenience at best, or a fire or serious failure at worst.

The most common needs for waterproofing connections are for boats and other marine vehicles, dune buggies and other off-roading vehicles, large aquariums, backyard ponds, and any other equipment that is exposed to exterior elements.

How to Waterproof Electrical Connections

Some methods for waterproofing wiring include:

  • Liquid electrical tape
  • Self-fusing silicone tape
  • Adhesive lined heat shrink tube

You’ll also want to have tools like a heat gun or a butane torch, wire strippers, and a crimper. If you are replacing wires, it might be a good idea to look into marine-grade wiring since it is flexible, resistant to vibrations, and coated to protect the wiring from corrosion. Salt water is notorious for making corrosion worse. 


  • Strong power with 2 modes
  • Variable temp control & overload protection
  • Scientific ergonomic design & wide applications
IRWIN Vise-Grip Wire Stripping Tool

IRWIN Vise-Grip Wire Stripping Tool

  • Wire cutter with induction hardened cutting edge stays sharp longer
  • Strips and cuts 10-22 AWG
  • Pliers style nose allows wire stripper to pull and loop in wire
Wirefy Crimping Tool

Wirefy Crimping Tool

  • Professional crimping tool
  • Precise ratcheting mechanism
  • Adjustable crimping force

The jacket of the wiring is also important. You’ll want jacketing that is made out of urethane/polyurethane or neoprene. These are the best for working in wet environments and will react well to the waterproofing adhesives.

How to Waterproof Electrical Connections

How to Set up Your Workspace

Regardless of the exact method you are going to be using to waterproof your wires and connections, you will need to make sure you have done all of the following:

  • Disconnect any and all power to prevent sparking
  • Ensure the area is free of any moisture
  • Clean previous residue that can affect new adhesion
  • Remove any wiring that has evidence of corrosion

Wiring should be silvery or coppery. If the wiring is blackened or greenish, there is already corrosion present, and you will need to remove that before continuing. If too much of the wire is corroded, you will have to replace the entire wire.

Once you have a cleared workspace, you are good to start working.

Using Liquid Electrical Tape

Liquid electrical tape is good for small projects that only need a little bit of waterproofing or areas where getting tape placed correctly will be inconvenient. Liquid electrical tape can be applied to connections like soldered joints, butt connectors, spade connectors and screwed connectors.

Mix the liquid electrical tape and then apply it to the exposed connection. After applying the first coat, wait 10-30 minutes until it is dry to the touch, then apply a second coat. After both coats are applied, full cure should be about 4 hours but to be safest, it is best to wait overnight.

Permatex Liquid Electrical Tape

Permatex Liquid Electrical Tape

  • Weatherproof protectant for wiring and electrical connections
  • Goes on as a liquid and dries to a flexible vinyl polymer
  • Resists dirt, dust, chemicals, and moisture, ensuring that connections stay intact

Using Self-Fusing Silicone Tape

You’ll want to keep your wires and connections taught when using silicone tape in order to make the application easier. To make the process go smoothly, you can either fasten the ends to something or have an assistant hold it while you work. Silicone tape is good for any easily accessible joint or connector. 

Cut the desired amount of tape with a razor. Then apply it to the exposed area using a 2/3 overlap. The tape is very stretchy and the more you stretch it, the greater the bond will be. It takes about 24 hours to fully set and fuse together.

Permatex Silicone Tape

Permatex Silicone Tape

  • For use on connector wires and cables, pipes, and hoses
  • Tensile strength: 700 PSI
  • Dielectric rating: 10,000+

Using Adhesive Lined Heat Shrink Tube

Heat shrink tube is very useful when you are splicing wires together because you can put it over the splice and seal it to the wires. You can also use heat shrink tube on butt connectors. This method does require the use of a heat gun, butane torch, or at the very least, a lighter.

Once you’ve chosen the appropriate diameter for the exposed connection, cut it to the right length. You’ll want enough so that it will overlap the existing insulation, but using too much is unnecessary. A good rule of thumb is to go 5mm longer than the exposed connection on either side.

Then use a heat gun to make the tube shrink to seal around the connections. If your heat gun has multiple heat settings, you’ll want to turn it up to at least 250 degrees. Then, once it is cooled, you are good to go.

Young4us Heat Shrink Tube

Young4us Heat Shrink Tube

  • Material: polyolefin
  • Rated voltage: 600V
  • Shrink Ratio: 3:1, Round diameter: 3/8'', Length: 1.22M(4Ft)

Pros and Cons of Each

Using the heat shrink tube is the most secure way for ensuring waterproofing of your electrical connections. However, it can only be used when splicing wires or on butt connectors. Self-fusing silicone tape is the next strongest option, but it cannot be used in tight and small areas like the liquid electrical tape can.

Another benefit of using the heat shrink tube is that you can expose it to water as soon as the tube has cooled, whereas you must wait several hours for liquid electrical tape to cure and a full day for the silicone tape to set.

If you have the option, go for the heat shrink tube, then the silicone tape, then the liquid tape. While using a lot of heat shrink tubes can run more expensive than the silicone or liquid tape, the extra cost is usually negligible when factoring in the type of costly damage you are preventing.

Running a Cable Through an Enclosure

In the event that you have a sealed cable that you are trying to run through an enclosure on your boat or aquarium and you need to keep the pass-through point from leaking, you can use 3Ms Marine Adhesive to seal up just about any project.

One thing to keep in mind is that you cannot have any stress on the cable because pulling on the cable can break the sealant and cause a leak. 

3Ms Marine Adhesive

3Ms Marine Adhesive

  • Permanent bonding – above and below the waterline
  • Industry standard for over 50 years
  • Offers extended working time

Finishing the Job

Once you have waterproofed your electrical connections according to the method you chose, you are good to go. You’ll want to make sure you periodically check your connections. That way you will know at the first signs of water damage and corrosion.

Final Thoughts

Keeping your wiring waterproof is one of the most important steps to ensure that you have reliable electronics while still going out and having fun in wet and otherwise harsh environments. These are all great ways to keep your wires free from exposure to moisture.