Last night at approx 1:30 am my wife and I awoke to a firecracker sound coming from the attic over our bedroom. It was very loud. I climbed up into the attic and saw sparks popping off of the main AC duct, looked like it was coming from an area that had been sealed by aluminum tape. We turned off the main breaker in the house and the sparks continued.
It appears to be a chemical reaction of some sort, and not electrically created. If someone has ever heard of this or can give me some advice whether to call a Duct installer, or electrician it would be greatly appreciated.
Thanks!
Mark