Polyethylene tape is the most common option for waterproofing a junction box. Make sure to overlap each piece slightly to create a tight. This article provides step-by-step instructions on waterproofing electrical connections, including using liquid electrical tape, self-fusing silicone tape, and adhesive-lined shrink tubing. Works well for irregularly shaped connections. Each method gets rated on four criteria that actually matter for outdoor durability: Waterproof integrity: Can it survive submersion? UV and temperature resistance: Will it hold up after a.