Eww, and I thought our knob and tube wiring on the INSIDE was bad enough!
Lots of good advice already. We're almost done doing our 80 year old house without opening any walls, so I'll add a few things we've learned:
- Find your main vent stack. If your house is like ours, you may well have a TON of space around it to run wires through. We tried several other approaches to getting wires from the basement to the attic (through two stories) before wising up to this one.
- Cutting into baseboards is often easier than cutting lath and plaster. (Even when those baseboards are OAK!) Our lath and plaster doesn't come down much below the top of the baseboards.
- Pulling baseboards and/or crown moulding off, running wire, and reassembling is relatively easy. You will spend a bit of time with putty and paint after you put the trim back, but it's much easier than patching lath and plaster. (Pulling down the crown moulding allowed us to wire the ceiling lights on the first floor without using surface conduit or making huge holes.)
- We got very little use out of the long flexible drill bits, but tons of use out of the 18 inch (or longer) -rigid- drill bit extenders. Those are great, since you can swap out bits as they get dull, and you can use a couple of them together while working in tight spaces where a longer extender wouldn't fit at all. Most of our interior walls had firestops at about 5 feet from the floor.
- Fish tape is ok, but fish sticks are better unless you need to take a bend. Either may get stuck on the keying inside lath and plaster walls, but fish tape is especially evil in this regard. I understand it's great in conduit, but we did very little conduit.
- Pull with gravity when possible. (Pull from attic from outlet box, not from outlet box to attic.) Pull with a partner whenever possible. One person pushes the line into the space you're pulling through, the other person pulls out at the end, keeping light tension on the line at all times, to prevent getting hung up on lath and plaster keys.
- Dental floss with a small weight (like a nut) on the end works better than fish tape as long as you're working with gravity.
- We also used about 15 feet of flexible, skinny chain. You can drop it down from the attic and as long as some of it hits the hole in the mid-wall brace you've just drilled, it will fall through to the outlet hole.
- If your chain sticks to a magnet, you can attempt to catch it with a small but powerful magnet connected to a fish stick. This worked much better for us than trying to get two fish tapes to hook, but sometimes it just didn't work at all, if there were nails, etc in the space we were trying to fish through.
- If you've already got knob and tube running through your joists, consider using those holes (after removing the porcelain inserts) to run your wires, rather than drilling new holes and further weakening the structure.
Hope that helps! :)