Replacing wiring in an existing home is a big undertaking and can be fairly expensive - especially if you’re not planning on gutting the house to do it. However, if you ever plan any renovations to your home you should seriously consider replacing the knob-and-tube wiring at that time.

Although safe when it was first installed, the insulation has most likely deteriorated over the decades to where it may not be safe anymore. Another potential hazard is the common practice years ago for electricians to 'tap' new circuits onto the knob-and-tube wiring to accommodate upgrades in the house. More often than not, these taps were not made safely, and not enclosed in a junction box. Also, the additional electric loads found in today’s homes on this old wire can be a fire hazard due to overheating of the circuit.

On a positive note, most of the old cable we have seen is usually found to be in very good condition unless it spent many years in a damp location. The fraying insulation that you are encountering is mainly found at junction points where people changed light fixtures, switches, receptacles, etc. over the years.

All of the lights in my house flicker on and off. The flickering stopped completely for about a week and then started up again. Any  suggestions?

If all of the lights flicker together then I'd start at the panel. Check all connections for tightness. It could also be a loose connection at the main breaker. If all checks out there, then it could be loose connection in the outside service entrance.

As a last resort, you can contact your utility company... it's not uncommon for there to be a problem on lines feeding your house. Trees brush against them, etc. and that can cause the same symptoms.

How far can you run SO cord, carrying 120 VAC to a piece of equipment?

That depends on how many amps the piece of equipment draws when it is in operation. When using flexible cord such as SJ or SO, keep in mind that the flexibility is due to the use of stranded wires in the cable. While this aids in flexibility, it also adds greater resistance to the wire and can cause a condition known as current starvation to the equipment you’ve connected to it. While you may not notice a big difference when powering a light bulb (it might appear slightly dimmer), there would be a much larger effect to motor driven equipment. It may be harder for it to start, it may run slower, and there could be excessive heating of the cord. Over a prolonged period of use, this condition can prematurely burn out electrical equipment, necessitating a possible expensive replacement.

I was installing a light fixture when two of the wires in the box touched (power was not turned off first). There was a small spark and the breaker tripped. After resetting the breaker, I still have no power in the room. Any thoughts? Blew switch out?

It's possible. You may have also caused a connection to break somewhere in the circuit (not necessarily at the sparking location). A tester at each junction point in the circuit should help you to quickly find the problem. Be sure to also check for a loose neutral connection as a possibility.