Entertainment Center: TVs, Stereos, VCRs and DVDs - Mystery Wire Cut - what to do?

While running a cable TV wire from the Attic, through a second floor room and down to the kitchen I had a particular struggle drilling from the 2nd floor down to the 1st floor. Even using a 16 inch drill bit extension I was not coming through on the other side.

I tried to drill up from the kitchen, expecting the two holes to intersect. It didn't go well. The end of that story is that I ended using a different approach from outside the house and the TV is installed.

The problem is that during the struggle I think I may have cut a wire of some sort. It was during the drilling up from the 1st floor part. It is an exterior wall. There appears to be a space above the top plate and when I peer through the hole that I drilled the I see what looks like the end of a wire in that space. It's a very small, single silver wire. I can't get a good look at it because of the angle, etc. I doesn't look like it could possibly be an electrical wire.

Everything in the house still works fine - electrical, telephones, etc.

I know that you are supposed to map out all of the wiring in your home before drilling and fishing wires - but since my basement is completely fixed it is pretty much impossible for me do.

Does anyone have any idea what this wire might be? How can I confirm it? What can I do about it?

It could be an alarm or thermostat wire.

How old is the house?

Is the wire silver or is the wire insulation silver?

Doorbell still work?

Could you just be seeing a nail that the drill hit and is now shinny? You don't say if you could see two ends of wires.

You might wnat to see if something stops working OR knock a larger hole and try a trace it.

To Satellite Guy: it's a good thought but the thermostat is on the other side of the house and there is no alarm.

To BobF: house is 20 years old.

The wire is silver or maybe darker but definitely not copper. It's really hard to see because the hole is down below the crown molding - so I'm not positive as to whether there is insulation or it is a bare wire but tapping on it makes a tin-ey sound that makes me think that it is bare.

To StickStan: it's definitely not a nail because it bounces when I tap on it. I can only see one end of it but it is possible that there is another end that I can't see.

I know I may have to knock a larger hole to check it out - I'm just trying to avoid that - I have a nice small 3"x3" hole now and bigger will be more noticable.

Of course, no size hole is worth a risk to life and limb....

Ok 20 yo house rules out the old type of wiring. Its not electrical - you'd be able to tell if it was.
I don't think its phone wire either. Phone wire has at least 4 wires with colored insulation inside gray insulation.
Thermostat wiring usually runs down an inside wall, not an outside wall.
It could be for a doorbell or burglar/fire alarm system.

Ok - I'm going to chalk it up to either a mirage or nothing to worry about - there is no current alarm in the house and all current doorbells work. Maybe it's a vestige of some old install.

Thanks for your help.

What are the chances of it being an old 2 wire antenna feed.