Quote Originally Posted by NH93 View Post
ALUMINUM FOIL TAPE!! No duct tape!! Foil tape is fire-proof. You can find it in any hardware store near the heating and cooling section!
From what I've read, Flexwatt recommends duct tape over foil due to the risk of foil creating a short. Properly functioning heat tape should never come even close to hot enough to ignite duct tape. If so, any duct tape left in the sun would combust, and I'm pretty sure we'd hear about that on the news.

I'm not recommending one over the other, though. As long as the heat tape is regularly inspected and free of damages, there shouldn't be any risk with either.