Q: I am trying to make a homemade meat smoker. I have been given a used industrial electrical box, which is fire rated, but I was told it is powder coated. As far as I know, it looks like the typical gray colour of most electrical boxes.
In your opinion, would this be safe to use?
A: Great idea — I’m always looking into ways to convert or resurrect useable stuff around my house. The electrical box that you are considering converting into a smoker is most probably coated with a UL-approved epoxy-polyester powder coating.
Hybrid epoxy-polyester powders are rather benign from a toxicity profile. It is the same chemistry that is used to coat the wire racks in refrigerators. These products can withstand continuous heat at around 350°F. If you expose it to temperatures much higher, the coating will eventually degrade and show signs of failure (loss of adhesion, flaking, etc.).
In designing your smoker, I suggest that you try to isolate the wood-burning process from direct contact with the coating. An inch or two should suffice.