Tip du jour... Drip loop. There is no way to prevent water from forming on a cable or wire and then following it downward. So we use a drip loop. it can be a "belly" in the wire before it gets to your junction box or wall penetration or a loop. Water will run to the lowest point and drip off rather than continuing into your equipment. It is also advisable to bring wires into the bottoms of boxes rather than the sides if possible.

Your HVAC air handler will condense water when the air conditioning is running. That water has to go somewhere. If you just straight pipe it to the outside world, a portion of your precious cool air will escape out the pipe. The trick is to install a trap in the line with a "dip" that is greater than the inches of water pressure in the HVAC air handler. Water will fill the trap and stop errant air flow. When the trap over fills only the excess water will run down the drain.

Two additional details. There needs to be a vent (or vacuum breaker) to prevent the drain pipe from siphoning all the water out of the trap, and TWO you need to install a drip pan under the HVAC unit with a shut off float switch. That way if the drain pipe gets plugged up and water backs up in the air handler, it will drip into the pan instead of your ceiling. The float switch will drop the HVAC system until you solve the problem.