Careful Rewiring Techniques


Do you need to replace older, existing wiring in your house? Whether it’s knob-and-tube wiring, BX wiring, ungrounded Romex, or aluminum wiring, you’ll need to make some holes in your plastered walls or ceilings to fish the new wiring around. Yes, that’s right. Unfortunately, there’s no way around this fact. But don’t fret. It’s not all bad news!!

If your home has an unfinished basement (with open ceiling joists or NO ceiling), all the outlets and switches on the floor above are accessible from the unfinished basement. In other words, most of these items can be rewired with little to no damage. However, lights will require some small holes to fish the wiring from switches to the fixtures. (I’ll explain more about lights later.)

If you have an unfinished attic, even better! EVERYTHING below this floor will be accessible from the attic space. We would be using this attic space to fish new wiring to all the lights, outlets and switches.


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Here’s a good photo of an unfinished basement. Note that “unfinished” means no drywall or plaster on the ceiling and walls. You can clearly see the joists and the wiring within. We frequently ask homeowners over the phone whether they have an unfinished basement. A lot of them say they do, but when we get there, it’s finished.

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This example of an unfinished attic has quite a bit of knob-and-tube wiring running about. In an unfinished attic, electricians can pull insulation away and drill down into the walls below, which will avoid holes in the finished plastered walls and ceilings on the floor below it.

The most difficult floors to do are ones that are sandwiched between two finished floors. (Think the 2nd floor of a three-family house.) These floors have NO unfinished spaces above or below them, so holes will be needed to fish wiring to all the lights, outlets, and switches. Now you may be asking, “Well, how big are these darn holes?”

Great question! We normally use a 1” drill bit. But as you may realize, older lath and plaster walls tend to fall apart a bit when drilled into. Sometimes, the holes can be a bit bigger than 1”. They might be 1.5” or so. But they’re usually not larger than that.

Below are two good examples of the kinds of holes you’ll need to fish wiring from a switch to a light on a floor that DOES NOT have an unfinished attic above it.

The picture above illustrates the holes needed to transition from wall to ceiling quite well. You may have also noticed the patching around the switch box. When we remove the old box, the plaster sometimes falls apart around it and needs to be patched in. This situation is really dependent on the condition of the plastered wall.

The above picture shows the route we took from the switch box to the light: one hole on the wall (behind the wallpaper), one hole on the ceiling right above it, and one more hole in line with the light. This route allows us to fish the wiring from the switch box to the light.
You may notice the other hole we made near the switch box. This hole was due to the cellar below, which didn’t extend far enough to fish up directly below the switch box. We had to come up in the bay next to it, then drill through one stud to get into the location of the switch box.

Additional Headaches fishing wiring

There are a few more issues that can come along to spoil the day, even on first floors. If your home has a lot of chair rails, a horizontal piece of wood spanning the wall studs is often at the height of the chair rail. Sometimes, you can sneak the snake/wire around it. But more often than not, a hole or two are needed to drill through it.

Here are some issues you may encounter:

  • Wind braces This kind of brace is really common in older homes. It’s a piece of wood in every outside corner of a house, which runs diagonally between the wall studs. These braces are impossible to fish through, and they require notching or drilling holes in the wall.

  • Random blockings Lots of older homes (especially those built before 1880) will have random pieces of wood in the walls and ceiling—seemingly for no reason at all. It’s almost as if the builder at the time had a few extra few pieces of wood and said, “Oh, just put them in the wall!”

    One home we rewired in Marblehead was built in the 1760s. Boy, was it a tough one. First off, every wall was extra thin, so it required special boxes. On top of that, there were random blockings EVERYWHERE. Fishing across a 10’ dining room ceiling (which is normally VERY EASY) took over four hours in this home.

    During that job, we learned a lot about homes built in the 1700s. Or I should say we learned how to properly price them—because they take twice as long!!

Have Wallpapered Walls?

Wallpaper can pose some issues. As I mentioned earlier, some holes need to be made to fish the new wiring. Depending on the condition of the wallpaper, it can often be sliced, peeled away from the wall, and glued back. If the wallpaper won’t peel, it typically rips. To see an example, take a look at the photos below. But try not to judge the wallpaper design!


We’ve worked in many homes with wallpaper, and we’ve had really good luck with slicing it, peeling it back, and gluing it back in place. If enough care is taken, you can complete this process without even noticing the wallpaper was disturbed!
Disclaimer: On occasion, the wallpaper will not peel off the wall, and it rips!


We really love to get creative and find new and different ways to accomplish rewiring jobs with as few holes as possible. If you’re concerned about what will be required to rewire your house, please give us a call today. We’d be happy to come out and educate you about the specifics. We never back down from a difficult house. In fact, we look forward to the challenge!