Just last week I drilled into a wall to install a light switch and managed to find a little pocket on top of some cross-bracing where several mice apparently had fallen during the remodel job. They came pouring out of that hole immediately, five or six of them, jumping down to the floor and taking off.

And over the years, I've drilled into just about everything you can drill into -- pipes, wires, ducts, you name it. That's just part of the fun of working on old houses.

At least you didn't drill through a mouse :-)

I drilled through a coworker once (I told him not to put his hand there).

I left a fellow and asked him to drill through the sill plate of the old place we were working on. The plate was somewhere around a 10" x 10" and had to be drilled from outside the house. When I came back he said we needed a new 1" bit. I asked if he broke it. He said no it was stuck and there was no way to get it out. This was an 18" bit and I knew that the old 1/2" Craftsman drill had never been stuck. If you could hold it, it would twist until the bit was buried.
When I went and checked on the stuck bit, I found that since he couldn't find an extension cord long enough, he had just hooked a plug and receptable on either end of a 250' roll of 12-2 Romex:-) I can tell you that there had to be some voltage drop. We found a 100' #12 cord and the bit came right out using the same drill.
An old timer told me that there was more voltage drop if the wire is coiled. Is there evidence for this?

When the wire is coiled it is like a big transformer. It can overheat or give greater voltage drop.

... it is like a big transformer ...

I guess you mean choke rather than transformer.

I've read this too, but I don't see how. The cable comprises two conductors carrying current in opposite directions. The fields should cancel and have no net effect. I'll admit my physics is rusty; what am I missing here?

A coil of wire carrying AC puts inductive reactance back into the cc't. It is a form of opposition to current flow, measured in ohms, and calculated by Xl= 2IIFL, where the inductive reactance in ohms is equal to 2 x Pi(3.14) x frequency of the AC in Hz x inductance of the coil in Henries. The tighter the coil and higher the AC frequency, the greater the effect of the coil on the cc't.

I'm sure that brickeye will be adding his 2 cents from an engineering standpoint shortly, and he will no doubt say that this is all wrong. However, I'm giving you the basic idea of it.

A coil of wire carrying AC puts inductive reactance back into the cc't.

Sure, but inductance depends on the effect of the magnetic field produced by the current in the coil. What you have here is TWO coils of wire. The current in one is flowing in the opposite direction to the current in the other. The fields should cancel and it should thus have little or no net effect, right? What have I forgotten?

Maybe because the neutral wire doesn't give off any magnetic flux? Isn't that why a tic tester won't register on a neutral?

All I know is that if you don't unwind a coiled up cord and use a heavy load on it it will overheat or not run your power tool because of voltage drop.
Choke might be a better term than transformer.

Maybe because the neutral wire doesn't give off any magnetic flux?

No, any wire carrying current has a magnetic field.

Isn't that why a tic tester won't register on a neutral?

No, a volt tic doesn't detect magnetic fields, it detects electrical fields. I think I recall that mine reacts to neutrals anyway, though I might be remembering incorrectly.

This has little or nothing to do with electrical but is the most interesting drilling accident story I ever heard, back in 1980.

Here is a link that might be useful: Drilling in the wrong place.