well it sounds like a cordless drill is not a good option when you suspect wires are in the wall.
You shouldn't use any drill if you suspect live wires in the wall. The safest thing to do is turn of the power and use a non-contact voltage detector just to make sure.
Power tools are sold all over the world, ever tried picking up a wire through solid rock ? in some countries walls are 2+ feet thick, you don't always know what is in there. If the earth does fail the RCD will protect you, after all if we go on the assumtion your doing it right and using a wire detector and doing it properly you'd also not be working without an RCD. Portable RCD's are also available. I use one on my saw