I am very concerened about your drill. The drill you mention is broken and should be thrown out. It represents a serious danger to the person who does not know that it must be operated with rubber soles in dry conditions only, and away from all grounded objects. If a person were to accidentally touch a metal pipe, or for god's sake, try to drill a hole in their properly grounded siding, they could be electricuted and die.
Get a new one, and ground your house while you are at it. You can probably do both for less than $100.
Frank Leibly Taftsville, VT
P.S. If you want a detailed explanation of why things are grounded, I would be happy to provide one. It's kind of obvious if you think about the fact that most people stand with their feet on the ground. Also remember that current through YOU is what kills you. Therefore high voltage is what's dangerous to you (current through your body is a function of the voltage difference that you bridge with your body). Keep everything around you at zero voltage and you are safe - even if there is current flowing through your siding.