CMC DIY Electrical Guide: How to Trace a Wire with No Power

Sep 9, 2021

how to trace a wire with no power

There are ways to trace wires without breaking apart your walls. The easiest way is to turn all the breakers off at the panel, and turn one on at a time to see what electronic device works. But what if there is no power or the power is off? That’s okay. You can still figure out where wires are even if you don’t have an electrical blueprint.

What You’ll Need to Trace Wiring

There are a few handy tools that can help trace electrical wiring. Readily available and simple to use, these include:

  • Stud Finder: A device that emits a small electrical or magnetic field to detect changes due to denser areas of the wall or metal nails. Depending on the unit, it may detect wires behind walls too. Changes in density are revealed with light or sound.
  • Circuit/Wire Tracers: Are designed specifically for locating electrical wiring, whether it’s behind a wall or underground. These are more expensive and most often used by professionals; they are better suited for more extensive electrical work. Nonetheless, they’re very effective at finding both energized and de-energized wires.
  • Voltage Detectors: When working with wires, it’s very important to know whether electricity is flowing through them. An audible alarm voltage detector, or tone generator, makes a sound when it encounters a live wire. Neon circuit testers can be used as well. If you need to know how to test electrical wiring, these options help you quickly find where wires are and trace a specific wire if some are tangled.
  • Metal Detector: Wires may look colorful and soft, but that’s just the insulation. There’s metal at the core of each wire, so a metal detector can help trace their location. This works better if there aren’t too many wires or metal objects in the walls.

How Do I Know Where to Look?

You might be concerned about false wire readings. But here is a good rule of thumb that can help you start looking. Most home wiring is installed about 6 or 12 inches above receptacles, an inch deep into the wall. It is also usually placed in a horizontal configuration. Tracing a wire therefore doesn’t have to seem like a random process.

Checking for Incorrect Wiring

Tracing circuit or switched outlet wiring can be done for many reasons. Some of the issues you can look for (when the power is off), include:

  • Reversed Connections: This applies to older, two-prong electrical outlets with one long and one short slot. Plugs only go in one way, which is a safety feature of polarized outlets. But if the circuit wires have been installed wrong, backward polarity can cause an electrical hazard. Once you’ve traced such wiring, inside the outlet, the black wire should be connected to the brass terminal and the white wire should be connected to the silver terminal.
  • Grounding: A ground connection allows electricity to safely flow from your home to the earth. It’s often not found in homes built during or before the 1950s. If a receptacle tester indicates there’s no grounding, you could use a tracer to run a ground wire, or to find a ground wire that may not be properly connected to the electrical box behind the outlet.
  • More Than One Wire Per Screw Terminal: If, while tracing a wire, you find more than one wire connected to a single screw terminal, there’s most likely a poor connection. However, you can join the wires with a wire connector and pigtail (and even trace them back to their source). A short length of the same wire, a pigtail is what safely connects to the screw terminal.

Contact CMC Electric

At CMC Electric, our trained technicians can perform any type of wiring and re-wiring work. They know how to trace a wire with no power, so if you don’t have the tools or confidence, they’ll safely check wires that run to receptacles, phones, home theater systems, and more. We include safety evaluations with every service and offer a 100% satisfaction guarantee and lifetime warranty on wiring work. To schedule same-day service, call 919-335-7109.

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