When it is time to replace wiring in a building?
When the demand for power increases. They're many form of wiring. Knob and tube, brown rag wire( no neutral) BX and Romex style. All depends on your needs. Knob and tube is extremely antiquated and can be dangerous. You could also consult an electrical company and have them go over your house with you and see what they say. Most companies can give you an estimate or diagnosis on the electric in your home for free
Some places require a re-wiring of a home if you replace the main service panel and the wiring is old, such as post and wrap or two conductor. In general, unless you have very old wiring, have had a fire, or need to upgrade your power availability in a room, you will not need to replace the wire. And my advice, if you have ANY post and wrap, or cloth insulated two-wire, get it replaced. That stuff is a fire hazard, as the rubber and cloth in those kinds of wires breaks down after decades, and can allow arcing to occur. Which can lead to a house fire.
Should your power needs increase, you can add additional circuits without having to replace the existing ones. Typically you'll need to replace wiring if it has become damaged or is otherwise worn out. Wires may be damaged due to a variety of reasons. Rodents are notorious for chewing on exposed wires in attics and other crawl spaces. Construction and re-modeling may damage wires. Wires can also wear out due to age or extreme conditions of heat or cold. Very old wires used before the 1960s made use of rubber and fabric for their insulation. These materials would degrade over time, resulting in shorts and arcing, which poses a fire hazard. These wires should be replaced - at a minimum, they should be protected with an arc-fault interrupter circuit protector. There is some debate that older copper wire contains too much oxygen, which can cause issues, but this is not conclusive yet. In some cases, you might need to replace older wire in order to make use of modern appliances. For example, very old homes might utilize 3-wire 240 volt circuits. Modern 240 volt appliances, like your kitchen stove, cannot use this wire - they require a type of cable with 4 wires.
