The Ins and Outs of Rewiring an Old House

Rewiring an old house

I’m sure you’ve heard the stories: “Old wiring” caused a fire, which burned the house down! And now that you’re in the market for a fixer-upper (or just bought one!), you’re wondering what that even means. What is old wiring? Do I have it? Is it safe? Do I need to rewire the house? What’s involved in that!?$?

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Old Wiring is Not an Official Term

Electrical fires do happen, and they’re certainly more common in older homes than they are in newer ones, but there really isn’t a single definition of “old wiring.” Well, I guess what I mean is that there isn’t a single “limited” definition of old wiring. The original “knob-and-tube” electrical wiring in an old home would certainly qualify as old wiring and needs to be replaced immediately. But what about the house built in 1950 that seems to have pretty normal stuff going on?

Here are a few things to look for. This list is by no means exhaustive and electricity in your home should be taken very seriously. If you have any questions about your wiring, don’t hesitate to have an electrician come out and give you a professional report.

Knob-and-Tube Wiring

knob and tube wiring
Knob-and-tube wiring inside a circa-1930 Pittsburgh house. Source: Laura Scudder.
Usually found in homes close to 100 years old or older, knob-and-tube wiring goes way back to the early days of residential electricity. The system utilizes single wires, usually but not always insulated with a cloth wrapping (I’ve seen bare copper), that are run between “knobs” to keep wires off the wood framing and then through “tubes” anywhere wires need to go through the wood.

If you have a house with this kind of wiring, you do need to rewire.

Cloth Wiring

cloth wrapped wiring
Cloth-covered wiring in an old switchbox. Source: bfink.
“Cloth wiring” refers to wires that are sheathed in cloth insulators rather than rubber or plastic. Cloth wiring isn’t as clear of a “you must replace it” kind of call, but most electricians (and most insurance companies) would suggest that you do. The cloth insulator is sometimes flammable while also more prone to wear. In a home with decades upon decades of living under its belt, the combination could be unsafe.

Aluminum Wiring

aluminum and copper wire in home
Aluminum copper pigtail splicing. Source: Peterson Electric
Aluminum wiring is another type of wiring that’s not seen in residential use today. Aluminum tends to expand and contract more than copper wiring does over time. This causes the connections in junction boxes and at light fixtures to loosen more readily than copper. Eventually a loose connection has the potential to cause a fire.

If you have aluminum wiring, you should have the entire system checked by a qualified electrician. It’s possible that all you need is some maintenance, but once again, many electricians and insurance companies will recommend or require replacement.

What Does Rewiring a House Entail?

There are two kinds of rewiring situations.

One is a major remodel where the house has been gutted and all of the walls and attic are exposed. If this is the situation with your fixer-upper, then it makes good sense to go ahead and upgrade your entire electrical system while the house is open. There won’t soon be another opportunity to wire the house properly and completely without doing additional demolition and repairs.

If, on the other hand, you’re considering rewiring a house that isn’t being opened up completely, it’s kind of a different ballgame. Rewiring a house with closed walls and ceilings depends on a few things:

  • Attic access and room enough to work in the attic
  • Basement access to the underside of the first floor
  • What type of wall and ceiling materials you have
  • How the house is insulated
  • Type of wall construction (frame, concrete, metal studs, etc.)
  • Complexity of the electrical system
  • The skill and “mindset” of the electrician

This last one is very important. I’ve seen rewiring so meticulous that painting was barely necessary when the electrician was done. On the other hand, I’ve seen jobs that looked like someone went from room to room, randomly swiping with a giant chainsaw. In the latter circumstance the cost of repairs can vastly exceed the cost of the rewire itself.

For this reason, I would say that a rewire job deserves an extra dose of due diligence. Spend time interviewing a few electricians and asking them their thoughts on what kinds of repairs will be necessary when they finish. You’ll get an idea of what I mean by “mindset” when you do this. Be sure you talk to customers of the electrician you’re considering before you hire him or her. And insist that the work be permitted and inspected by the local building department.

Old Wiring Can Be Replaced

Rewiring a house, much like replumbing a house, can be a big undertaking. It comes with real advantages however. You’ll have peace of mind, you’ll likely have more effective electrical service in your house (better switches and lights, etc.), and you might just get a discount on your homeowners insurance!

It can be done and it’s one of those projects that, if you need it, is worth every penny.