Before you blow another fuse trying to start your computer, here’s what you need to know about old electrical wiring:

Characteristics of Old Electrical Systems

Does your home need to be rewired? First, you should understand what makes outdated wiring different from newer arrangements. Here are some of the electrical issues typically found in older homes:

Outdated electrical panels. Buying an older home? Unless it was rewired in the recent past, it’ll probably come equipped with older electrical panels. An electrical panel, also known as a fuse box, receives power from your local electric company and distributes it throughout the circuits in the home. Older panels often don’t have sufficient power for modern-day needs, which may cause breakers to flip because they can’t handle the electrical load your family demands.

Aluminum wiring. In the 1960s and 1970s, electricians commonly used aluminum wiring because it was less expensive than copper. They didn’t always optimize these systems for aluminum’s idiosyncrasies, however, which led to higher failure rates at connection point — causing sparks and short circuits.

While aluminum isn’t necessarily bad, it’s simply not as good as copper. One potential safety hazard of aluminum wiring is known as “creeping” — when connections loosen over time. Not only does this hinder your ability to power devices as needed, but these gaps between the wiring and connectors may lead to overheating and potentially even house fires.

Cloth insulation. Prior to the 1950s, the insulation that covered electrical wires was made of cloth. Since cloth is vulnerable to the elements, it becomes brittle and deteriorates over time. It’s pretty rare to come across cloth insulation today, but if you have old-school knob-and-tube wiring in your home, you may still find the remnants of looms — the cloth insulating sleeve that protected wires as they ran into appliances or walls. If your home’s wiring setup is so old that you still have looms, you definitely need an update.

Knob-and-tube wiring. A popular method from the late 1800s to the 1940s, electricians formerly used porcelain knobs to anchor wires to studs, floor joists, and insulated tubes in order to pass wires through walls. Since this type of wiring doesn’t include a ground wire, it’s dangerous for appliances that require a three prong outlet — which, if you look around your home, is now most of them.