How to Check for Power With a Multimeter

What a multimeter tells you about power

A multimeter is a handheld tool that measures electrical current, voltage, and resistance. When you use it to check for power, you are measuring voltage — the electrical pressure pushing through a wire or device. If voltage is present, power is flowing. If the reading is zero, the outlet, cord, or device has no power reaching it.

The multimeter gives you a number on a small screen. That number tells you whether something is dead or live, and how much electrical force is behind it. This matters because you cannot see electricity, so a multimeter is often the only way to know for certain whether a device or outlet is safe to touch or whether a cord is broken inside its plastic jacket.

Most multimeters have a dial or buttons to switch between different measurement modes. The mode you need is called DC voltage or AC voltage, depending on what you are testing. Household outlets and most devices use AC voltage. Battery-powered devices and phone chargers use DC voltage.

Key Takeaways

Set your multimeter to AC voltage mode for household outlets and appliances, or DC voltage mode for batteries and chargers.
Touch one probe to the hot slot (the smaller opening in an outlet) and the other to the neutral slot (the larger opening) to read voltage.
A reading of 110 to 120 volts means the outlet has power; a reading of zero means it does not.
Always keep both hands on the multimeter and never touch the metal probe tips while they are in contact with a live outlet.

Setting the multimeter to the right mode

Open the multimeter and look at the dial or the buttons on the front. You will see labels like V, A, and Ω (omega). The V stands for voltage. Next to it, you should see a wavy line (~) for AC voltage or a straight line with dots (—) for DC voltage.

For a household outlet or a plugged-in appliance, turn the dial to AC voltage. The label usually says V~ or ACV. For a battery, a phone charger plugged into the wall but not connected to a phone, or any device powered by a battery, turn the dial to DC voltage, labeled V— or DCV.

If your multimeter has buttons instead of a dial, press the button labeled V or Voltage, then use the up or down arrow to cycle to AC or DC. The screen will show which mode you are in. Start with a lower voltage range — 200 volts is a safe choice for household testing — because the multimeter will give you a more precise reading on a lower range.

Testing a household outlet

Set the multimeter to AC voltage mode and choose the 200-volt range. Look at the outlet. The slot on the right side is narrower — that is the hot slot, where power comes in. The slot on the left is wider — that is the neutral slot. The round hole below both is the ground.

Hold the multimeter in one hand. With your other hand, insert the red probe into the hot slot (the narrow one) and the black probe into the neutral slot (the wide one). Push them in until they touch the metal contacts inside. Do not let your fingers touch the metal tips of the probes while they are in the outlet.

Look at the screen. If the outlet has power, you will see a number between 110 and 120. If the number is zero or very close to zero, the outlet has no power. Write down what you see. Then remove both probes at the same time and pull them straight out.

If you want to test the ground, insert the red probe into the hot slot and the black probe into the round ground hole. You should see the same voltage reading — around 110 to 120 volts. If the ground reading is zero or much lower, the outlet may not be grounded correctly.

Testing a battery or DC device

Set the multimeter to DC voltage mode and choose the 20-volt range for a standard battery. Look at the battery. The positive terminal is usually marked with a plus sign (+) and is often the raised bump on top. The negative terminal is marked with a minus sign (−) and is usually flat.

Touch the red probe to the positive terminal and the black probe to the negative terminal. Hold them in place for a second. The screen will show the voltage. A fresh AA battery reads about 1.5 volts. A fresh 9-volt battery reads about 9 volts. If the reading is much lower — say, 0.5 volts on an AA battery — the battery is dead or dying.

For a phone charger or other DC device, look for the label on the back or bottom. It will say something like "Output: 5V 2A" or "12V 1.5A". The first number is the voltage you should expect to see. Set your multimeter to a range slightly higher than that number. For a 5-volt charger, use the 20-volt range. For a 12-volt device, use the 20-volt range as well.

Reading the multimeter screen

The screen shows a number and sometimes a unit label like V or mV (millivolts). The number is the voltage the multimeter measured at that moment. For a household outlet, expect to see 110 to 120. For a battery, expect to see the voltage printed on the battery itself — usually 1.5, 9, or 12 volts.

If the screen shows 0.0 or 0, there is no voltage at that location. If the screen shows a very small number like 0.5 or 2, the voltage is present but weak — the battery may be nearly dead, or the outlet may be on a dimmer switch or a failing circuit.

If the screen shows a negative number like −120, you have the probes reversed. This is not dangerous — it just means you touched the black probe to the hot slot and the red probe to the neutral slot. Swap them and test again.

What to do if you find no power

If an outlet reads zero volts, check whether other outlets in the same room have power. Plug a lamp or phone charger into a nearby outlet. If that outlet works, the dead outlet may be on a wall switch — look for a switch nearby and flip it on. If no outlets in the room work, the circuit breaker for that room may have tripped.

Go to your circuit breaker panel, usually in a basement, garage, or utility closet. Open the door. Look for a switch that is in the middle position or flipped the opposite direction from the others. Flip it all the way off, then flip it back on. Return to the outlet and test it again with the multimeter.

If a battery reads zero or very low, it is dead and needs to be replaced. If a device plugged into the wall reads zero on DC voltage mode, switch to AC voltage mode — you may have been testing in the wrong mode. If it still reads zero, the charger or power supply is broken.

Safety rules when using a multimeter

Never touch the metal tips of the probes while they are in contact with a live outlet or device. The metal conducts electricity, and you could receive a shock. Always keep both hands on the multimeter body, away from the probe tips.

Do not test outlets or devices if you are wet or standing on a wet floor. Do not test if you are touching a metal pipe, sink, or other grounded object. Water and metal both conduct electricity and increase the risk of shock.

If you are testing a device that is plugged in and powered on, be extra careful. Some devices have high voltage inside even when they appear off. If you are unsure, unplug the device first, test it, and then plug it back in.

A multimeter itself is safe — it does not produce electricity, only measures it. The risk comes from the live electricity you are measuring. Treat every outlet and every powered device as potentially dangerous until the multimeter tells you otherwise.

Frequently Asked Questions

Can I use a multimeter to test if a cord is broken inside?

Partially. Unplug the cord first. Set the multimeter to resistance mode (Ω). Touch one probe to each end of the cord. If the reading is zero or very close to zero, the cord conducts electricity and is probably fine. If the reading is very high or shows infinity, the cord is broken inside. However, this test only tells you if the wire conducts — it does not tell you if the insulation is damaged or if the cord is safe to use.

What does it mean if the multimeter screen shows a negative number?

It means you have the probes reversed — the red probe is on the negative side and the black probe is on the positive side. This is not dangerous. straightforward swap the probes and test again. The reading will be the same number but positive instead of negative.

Why does my outlet show 120 volts but my device still will not turn on?

The outlet has power, but the device may have other problems. The power cord could be damaged inside, the plug could be loose, the device's internal power switch could be off, or the device itself could be broken. A multimeter only tells you whether voltage is present — it does not test whether current is actually flowing to the device or whether the device is working.

Is it safe to test an outlet while it is raining or very humid?

No. Water conducts electricity. If you are wet or in a very humid environment, wait until conditions are dry. If you must test in a damp area, stand on a dry surface, keep your hands dry, and avoid touching anything metal besides the multimeter.

Can I test a light switch with a multimeter?

Yes, but you need to test the outlet the light is plugged into, not the switch itself. Set the multimeter to AC voltage and test the outlet while the switch is in the on position. If the outlet reads 110 to 120 volts, power is reaching the light. If it reads zero, the switch may be off, the circuit may be tripped, or the wiring may be broken.

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.