Well, I can tell you the way I did one, might not be the best way though. There was a cat5 line running from the gate camera to the house that wasn't fully buried. Well, the lawn guys didn't see it and nicked a couple wires. So, I spliced it with a jack and put it in a waterproof conduit box. Used Great Stuff expanding foam on the inlet and outlet to make sure no moisture got in. Seems to be working ok. We've had a couple nice rains since then, and I've checked the box with no signs of moisture.