Multimeters for Home Inspectors

by Scotty Bane, InterNACHI® Certified Professional Inspector®
and Kate Tarasenko, Editor-in-Chief

One tool that home inspectors can use to provide more information and therefore more value for their home inspection is a multimeter.

Multimeters enable the inspector to check whether electrical wires are energized and if there is continuity in a circuit. (Continuity describes the complete, properly functioning and undamaged circuit.)  Multimeters can measure electrical values such as voltage, resistance, and current or amps. A multimeter can measure DC (or direct current) and AC (or alternating current) voltage. (DC voltage is of less concern, as this type of voltage is found in battery-operated systems.) 

There are two main styles of multimeters: analog and digital. Analog multimeters indicate readings using a needle on a gauge, while digital multimeters have an LED digital display This tool can be used in combination with a GFCI and AFCI tester. If the GFCI and AFCI tester indicates that the circuit is not grounded or wired improperly, the inspector can use the multimeter to check whether the power output is within regular range, and if is live or not. 

Electrical outlets typically have two plug-ins, each arranged with two positive inputs above and one longer ground that is centered below. GFCI testers simply plug in, and multimeters can be connected if rated for at least 20 amps. Typical 120-volt outlets have 15 amps, and 220-volt outlets have 20 amps.

Inspectors should test a representative number of outlets for proper functioning, which includes a voltage reading within 5 volts or 120 volts either way. Too much or too little voltage or amperage can cause a household device or appliance not to work properly and even cause damage. Too much or little voltage or amperage can also cause issues with devices when charging, as a high charge can cause the battery to blow up, and low charge can cause charging times to double or triple, using more power. 

Multimeters enable the inspector to be very specific about the power and condition of the circuit. It is possible for a circuit to be wired completely wrong and backwards, making the use of household appliances and power-consuming items work improperly. Multimeters will indicate a negative reading if the outlet is wired backwards. 

The average multimeter is the size of a large smartphone, and a bit thicker. The body of most multimeters is constructed of hard plastic and often comes equipped with a rubberized protective case. Meters have two leads: a negative lead, which is black; and a positive lead, which is red. It works by having the leads connected, with the black lead to ground and the red lead to the power input, which effectively makes the power in the circuit flow through the multimeter, making it part of the circuit so the meter can provide an accurate reading. After turning on the tool, the center toggle or button should be selected to test for AC voltage in the range just above the expected correct reading. If the inspector is testing a regular 120-volt outlet, s/he should place the tool to read AC in the range just above 120 volts. This is done by connecting the black lead to the common plug and the red lead to the plug-in port for either the amperage or voltage, depending on the reading desired.

Commercial multimeters cost anywhere between $60 to $1,500. It’s a good idea to write down the brand, model and serial number for your insurance company to protect yourself from theft.

In addition to applications for home inspections, multimeters are also useful at maintaining the inspector’s vehicle. If the vehicle won’t start, it’s very often due to a dead battery. If jumping the battery does not solve the problem, the battery may need to be taken out and charged. A multimeter can provide the data readings to determine whether the battery has sufficient amperage and voltage, or if it needs to be replaced.

In summary, a multimeter is a tool that can aid the inspector in creating a home inspection report with more depth and accuracy, which clients can use to make a more informed decision related to their property’s condition, as well as potential repairs and maintenance needs.