How to Check for Power With a Multimeter

What a multimeter tells you about power

A multimeter measures electrical current, voltage, and resistance. When you want to know whether power is flowing through a wire, outlet, or device, a multimeter shows you the voltage — the electrical pressure pushing through that circuit. If the reading is zero or near zero, no power is present. If it shows a number matching what you expect (usually 120 volts for a US household outlet, or whatever the device is rated for), power is there.

The multimeter does not tell you whether something is safe to touch or whether current will flow if you complete a circuit. It only shows you the voltage present at that moment. That distinction matters: a wire can show 120 volts and still be safe to hold in your bare hand if no current path exists. But a multimeter reading is your first step in troubleshooting dead outlets, checking whether a breaker has tripped, or confirming that power reached a device before it failed.

Key Takeaways

Set your multimeter to the DC or AC voltage setting that matches what you are testing — household outlets use AC voltage, usually 120 or 240 volts.
Touch one probe to the hot wire or terminal and the other to neutral or ground; the display shows the voltage between them.
A reading near zero means no power is present; a reading matching the expected voltage means power is flowing.
Always test the multimeter itself on a known live outlet before testing a dead circuit, so you know the meter is working.

Choosing the right setting on your multimeter

Multimeters have a dial or buttons that let you select what you are measuring. Look for settings labeled V with a wavy line (AC voltage) or V with a straight line (DC voltage). Household outlets, wall switches, and most home wiring use AC voltage. Batteries, car electrical systems, and many electronics inside devices use DC voltage.

Next to the voltage symbol, you will see numbers like 20, 200, or 600. These are the maximum voltage the meter can safely measure on that setting. For a US household outlet (120 volts), the 200-volt setting works. For a 240-volt circuit (like a dryer outlet), use the 600-volt setting. If you are not sure what voltage to expect, start with the highest setting — you can always switch down if the reading is too low to read clearly.

If your multimeter has an auto-ranging feature (often labeled AUTO), it picks the right scale for you. Manual multimeters require you to choose. Either way, never set the dial to resistance (Ω) or current (A) when testing for voltage — you will get a wrong reading or damage the meter.

Testing a known live outlet first

Before you test a circuit you think is dead, test your multimeter on an outlet you know has power. Plug a lamp into that outlet and turn it on to confirm it works. Then set your multimeter to AC voltage (200 or 600 volts), insert the black probe into the neutral slot (the longer slot on a US outlet), and insert the red probe into the hot slot (the shorter slot). The display should show around 120 volts.

If the meter shows zero or a very low number on a live outlet, the meter is broken or the probes are not making contact. Check that the probes are pushed all the way into the outlet slots and that the probe wires are plugged firmly into the meter itself. If it still reads zero, the meter needs replacement before you can trust any other readings.

Testing an outlet or wire for power

Set the multimeter to AC voltage and choose the 200 or 600-volt range. Insert the black probe into the neutral slot (or touch it to a neutral wire or ground) and the red probe into the hot slot (or touch it to the wire you are testing). Do not let your fingers touch the metal probe tips or the bare wire — hold the probe handles only.

Read the display. If it shows a number close to what you expect (120 volts for a standard outlet, 240 for a dryer outlet, or whatever the device is rated for), power is present. If it shows zero or a number much lower than expected, no power is flowing. If the outlet is dead but others in the house work, check the circuit breaker panel — the breaker for that outlet may have tripped and needs to be switched back on.

If you are testing a wire instead of an outlet, you may need to strip a small section of insulation to expose bare wire, or test at a connector or terminal. Never cut into a live wire. If you are not sure where to touch the probes, ask someone experienced with that device or circuit before proceeding.

Testing inside a device or appliance

If a device is plugged in but not working, you can check whether power reached the internal components. Unplug the device first. Set your multimeter to DC voltage (usually 20 volts for small electronics) and touch the probes to the power supply terminals or battery contacts inside the device. If the reading matches the voltage printed on the device (often 5, 12, or 24 volts), the power supply is working and the problem is elsewhere. If it reads zero, the power supply has failed.

Some devices have fuses or circuit protection inside. A blown fuse will show zero voltage on the output side even if the input side shows power. Replacing the fuse may restore the device, but if it blows again immediately, the device has a deeper problem and should not be used.

What different readings mean

A reading of zero or very close to zero (within 5 volts of zero) means no power is present at that point. The circuit is off, the breaker is tripped, or the wire is broken. A reading that matches the expected voltage (120 for a household outlet, 240 for a dryer, 12 for a car battery) means power is present and flowing normally. A reading that is much lower than expected (like 80 volts on a 120-volt outlet) suggests a loose connection or a failing power supply — the circuit is partially working but something is wrong.

A reading that is higher than expected is rare in household circuits but can happen if the meter is set to the wrong scale or if you are measuring between two hot wires instead of between hot and neutral. If you see an unexpectedly high reading, double-check that you have the right voltage setting and that the probes are touching the right terminals.

Safety reminders when using a multimeter

A multimeter is a measuring tool, not a safety device. It tells you the voltage present, but it does not protect you from shock. Never touch bare wires or metal probe tips while the probes are in contact with a live circuit. Wear shoes with rubber soles and keep one hand in your pocket or behind your back when testing live circuits — this reduces the chance that current will flow through your chest if you accidentally complete a circuit.

If you are testing a circuit in wet conditions or if you are wet, stop and wait until you are dry. Water conducts electricity and greatly increases the risk of shock. If you are not comfortable testing a circuit yourself, hire a licensed electrician — the cost of a service call is far less than the cost of a serious injury.

Frequently Asked Questions

Can I test for power without turning off the device first?

Yes, testing voltage with a multimeter does not require you to turn anything off. The meter draws almost no current and will not harm the device. However, if you are testing inside a device or appliance, unplug it first so you do not accidentally touch a live component while the meter is in your hand.

What does it mean if the multimeter reading keeps changing?

A flickering or unstable reading usually means the probes are not making solid contact with the wire or terminal. Push the probes in firmly or try touching a different spot on the same wire. If the reading is stable but lower than expected, the circuit may have a loose connection or failing component.

Can I test for power on a battery?

Yes. Set the multimeter to DC voltage and touch the red probe to the positive terminal and the black probe to the negative terminal. A fresh battery will show its rated voltage (9 volts for a 9V battery, 1.5 volts for an AA battery). A reading much lower than that means the battery is nearly dead.

Do I need a special multimeter for testing high-voltage circuits?

Standard multimeters are rated for household voltage (up to 600 volts on most models). If you work with industrial or utility-scale power, you need a meter rated for that voltage. For home use, a basic multimeter rated for 600 volts is sufficient.

What if the multimeter shows power but the outlet still does not work?

Power at the outlet does not mean the outlet itself is wired correctly or that it will deliver power to a device. Test by plugging in a lamp you know works. If the lamp does not turn on, the outlet may have a reversed neutral and hot wire, a broken connection inside the outlet, or a tripped ground-fault circuit interrupter (GFCI). Call an electrician to diagnose the problem.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.