We have a small balcony over an outside front entrance. There is appropriate water proofing system(flextile), drain and slope. HOW do you prevent drain freeze- in freeze thaw conditions? Our winters are long with ranges of 0 to -40 c, with everything in between with quick temp changes. We are afraid the pipe will freeze, with water in it. We need to know asap as the roof is being closed in. Our electrician is new to this -doesn't have a clue what heat trace to use, how to keep it safe.