One question that did come to mind about your solenoid project, which is very elementary but could be CRITICAL to your outcome.
Please tell us about your wire.Is it insulated or bare copper?
Solenoid coils are wound with enamel, resin, or some other insulation material. You mentioned almost burning down your home. Yep, that would happen if you used bare copper wire. Might be a pretty flame for a good bit!
Forgive me if this question sounds like it belittles your intelligence, but believe me we can't take anything for granted!