How to Waterproof Electrical Cable

Exposed wires.
  • 2 hours
  • Intermediate
  • 200
What You'll Need
Weatherproof Electrical Boxes
Sealing cable connectors
Wrench set
Cable ties (to make the drip loop)
Silicone rubber sealant
Plastic bottle

Water and electrical equipment don’t play well together, so if you want to protect your electrical cable from water damage, you’ll need to know the best way to waterproof it. This waterproofing includes work outside, on the roof, and indoors, closest to your electronic units. Below are instructions on how you can best waterproof electrical cable, as well as a few key tools you will need to do the job right.

Step 1 - Turn Off the Power

Whenever you work on electrical equipment, disconnect the power first. You certainly don’t want to get electrocuted.

Step 2 - Keep All of Your Connectors Tight

Using sealing connectors on all weatherproof electrical boxes, you can make sure connections stay tight. Hand-tighten the connectors first as tight as possible after which a proper size wrench can be used to finish tightening them up to another 1/4 turn.

Step 3 - Secure Electrical Cables in the Roof Area

Next examine the grounding block, dish, and general cable entry area, or wherever it is not completely protected by the roof. There you can construct the cable into a rain loop (or drip loop) to prevent rain from hitching itself to the cable connectors or the dwelling’s inside.

Step 4 - Waterproof Outside Connections

You can now use a 100 percent silicone sealant to coat your outside connections. (You can purchase this sealant at nearly every home improvement outlet.) When you apply this sealant, coat only the outside. Never put sealant on the threads and assembly because you will then need to cut them off. You shouldn’t attempt this coating if it is raining or damp outside. Instead, wait for a dry day.

If you think these connections have been exposed to any kind of moisture, dry them with a hair dryer or let them dry on their own before you perform your sealing. Also, use this sealant for the cable entry to the house. Applying sealant not only protects cables from water damage but also serves to prevent sun damage.

Step 5 - Protect the Switches

You can also protect your switches with a simple plastic bottle. Merely lop off the neck, attach it to the pole, with the bottle turned upside down and four holes punched into it for mounting the piece with tie wraps. Next, place the wired switch inside the bottle and use tie wraps to hold the bottle and switch in place.