Find Wire Breaks in a House With a Multimeter

A digital multimeter can help diagnose faulty wiring.
A digital multimeter can help diagnose faulty wiring. (Image: Polka Dot Images/Polka Dot/Getty Images)

House wiring may falter for several reasons, including an overloaded circuit, water damage or simply the natural wear that comes with age. Once weakened, a failing wire may break, reducing electrical flow and increasing the risk of fire. An electronic device called a multimeter can help locate wire breaks before they become a more serious problem.

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Function

A multimeter is a device that measures current, resistance and voltage to diagnose the performance of electronics and other electrical devices. Because they can measure current, multimeters may also determine the connectivity between two wired objects. The multimeter will detect if a wire break exists that disrupts the electrical current and saps voltage.

Description

A typical multimeter is a small, rectangular handheld device. The multmeter's front contains a display window, a large function dial and lead connectors. The device has two wire leads, one black lead for negative and one red lead for positive. Each lead has a holder for safe handling and an exposed tip for establishing a connection.

Types

A multimeter can be either analog or digital. An analog multimeter will feature a movable needle that must be read to determine measurements, while a digital multimeter has an LCD panel that displays all measurements. A multimeter may also be auto range, meaning the device switches automatically between ranges to generate the best reading, or manual switch, which means you need to manually change the range to achieve the most accurate reading.

Use

Among its many functions, a multimeter may test the strength of an electrical outlet to determine if any wire breaks exist. Set your multimeter for 400 volts AC to measure the outlet voltage. Insert a probe in the right outlet slot, which is hot, and another probe in the left outlet slot, which is neutral. The multimeter should produce a rating of 120 volts. While leaving the hot slot probe in place, remove the probe from the neutral slot and insert it into the ground slot, which is the more circular hole located beneath the two vertical slits. The multimeter should once again read 120 volts. Finally, remove the probe from the hot slot and insert it into the neutral slot while keeping the ground probe in place. the multimeter should now read zero volts. Any discrepancies in the volt readings may indicate a wiring problem.

Warnings

Follow appropriate safety precautions when working with electricity. Always hold the multimeter probes by the insulated safety handles to eliminate the chance of shock. If you choose to perform outlet or wiring repairs, always turn off the main circuit breaker.

References

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