I just bought a new house, and I'm installing a chandelier in the foyer. The house was built in the early 1900s and has knob and tube wiring. It didn't have an electrical box in the foyer so I cut the plaster and attached one to the joist. The problem is that when I turn the breaker back on, the chandelier is "hot." My voltage detection pen goes crazy when it's inches from the fixture, whether the switch is on or not. The lights work fine. I took down the chandelier and looked for exposed wires in the box; didn't see any but I put electrical tape around some of the K&T insulation that looked ragged. Still the same thing. Am I missing something? I'm starting to wonder whether there is a wiring problem with the chandelier, which is brass. Or is there something else I'm not thinking of? I am planning to buy a volt meter to see if it's "phantom voltage" but that seems unlikely to me since the voltage pen is going crazy even when the light is turned off. Thanks for any advice.
Shawn

Most likly the power is coming into the outlet and there's a switch leg running down to the switch from there.

Really need to bite the bullet at some time and get all that old wiring replaced.

shut off the power, take the chandelier down, and put one of those rubber-with-wires carnival sockets up there temporarily to hold a bare bulb.

get to a lighting specialty shop and find some retro-look cloth-covered wire, or find and order it on the Internet. get new ceramic sockets, take one to the home center to match them up.

rewire completely with all new RU-labelled (replacement UL listing) materials, and get a large crimp terminal that will fit a 3/8 inch bolt. you will unscrew the nut on the chandelier base, put that underneath it, then retighten the nut, so the matal of the unit is all grounded.

shut off power and reinstall.

if you have a restoration specialist in your area, I'd also get a quote for refinishing the chandelier. could cost $100-120 bucks to buff it to the metal and re-lacquer the piece. but it will look like a million bucks.