I dug holes in 50 cm of sawdust in the attic just now. Under the sawdust, I found plastic! The house was built before 1950 and I doubt there is a vapor barrier in the walls. The house is naturally ventilated.
So my questions:
1. What is the best way to make penetrations in the plastic when I need to run electrical wiring in the cold attic?
2. What are the risks associated with this retrofitted vapor barrier?
3. How can I minimize the risks?
So my questions:
1. What is the best way to make penetrations in the plastic when I need to run electrical wiring in the cold attic?
2. What are the risks associated with this retrofitted vapor barrier?
3. How can I minimize the risks?
Since plastic wrap did not exist until sometime in the 60s, you must have a later additional insulation. Before that, the vapor barrier was usually an asphalt felt. It is difficult to give a really good answer to your questions without knowing what the rest of the house looks like. However, I don't think your retrofitted plastic wrap can cause any major problems. The best principle is probably to try to keep it intact. As for electrical wiring, which is not my specialty, I think they usually try to keep it on the warm side. Tape it well, and at least you haven't disturbed anything.