3 Ways to Find Out if a Microwave Has Leaks

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3 Ways to Find Out if a Microwave Has Leaks
3 Ways to Find Out if a Microwave Has Leaks

At high levels, the extreme heat emitted by microwave radiation can cause health problems such as cataracts and burns. While most leaks in these appliances are too small to expose you to such risks, you may want to take precautions and test microwaves that look damaged or are more than nine years old. Home tests are cheap and easy, but remember that they only provide an estimate.


Method 1 of 3: Directly detecting leaks

Check a Microwave for Leaks Step 1

Step 1. Find a lamp that reacts to microwaves

Some objects react to their frequency:

  • A straight (non-compact) fluorescent lamp;
  • A neon "NE-2" bulb purchased at an electronics store, turned on and connected to a voltage divider so that it glows low;
  • Cheap microwave testers are often inaccurate, but serve as a first test;
  • A professional device can cost hundreds of reais. It is only needed in professional contexts.
Check a Microwave for Leaks Step 2

Step 2. Darken the room

Turn off the light so you can see the lamp glow if you are using one. If using a microwave test device, skip this step.

Check a Microwave for Leaks Step 3

Step 3. Place a glass of water in the microwave

Turning the device on empty exposes the magnetron (the energy source) to high levels of energy, which can damage or destroy it. A glass of water of about 275 ml, or a little more than a cup, will reduce this risk and still leave several microwaves unabsorbed for testing.

This measure is even more important in the case of older microwaves, whose coating around the magnetron may be of lower quality

Check a Microwave for Leaks Step 4

Step 4. Turn on the microwave and let it run for one minute

Check a Microwave for Leaks Step 5

Step 5. Slowly move the object around the microwave

Hold the lamp or tester, including the cord, at least 5 cm away from the oven surface. Move the object slowly (about 2.5 cm per minute) around the door seal and any places that appear damaged.

  • The microwave power rapidly decreases with distance. Test it at the distance you normally stand from the oven, for example, at the edge of the kitchen counter.
  • If the appliance stops before you are finished, change the glass of water and let it heat up for another minute.
Check a Microwave for Leaks Step 6

Step 6. See if any reaction occurs

The fluorescent tube will glow, and the neon tube will become much brighter if the microwave is leaking. Electronic testers react in different ways; therefore, check the manual. If the tester displays a measurement, anything close to 5 mW/cm2 at a distance of 5 cm is cause for concern. All these methods are just quick tests, even the one using the tester. They don't necessarily mean that your microwave is dangerous, but that it is worth taking some steps to fix the problem.

Method 2 of 3: Using a Notebook Wi-Fi Connection

Check a Microwave for Leaks Step 7

Step 1. Find two Wi-Fi enabled devices

Some networks use roughly the same frequency as microwave ovens (about 2.4 GHz), so the device's casing should block Wi-Fi as well. To test this way, you'll need a microwave-safe notebook and a second device that can connect to your home's Wi-Fi network.

The instructions below are for using two computers, but you can also use cell phones with Wi-Fi turned on if you know how to get them to test each other's latency

Check a Microwave for Leaks Step 8

Step 2. Set your WiFi to 2.4GHz

If you're not sure how to change your network frequency, go to your router's settings and look for information about "802.11 mode", usually within the advanced settings:

  • 802.11b or 802.11g means you are on a 2.4 GHz network. Go to the next step.
  • 802.11a or 802.11ac means you are on a 5GHz network. Some routers allow you to switch to another standard. This test will not work if your router does not have this option.
  • 802.11n can operate on both frequencies. Look for the frequency setting and set it to 2.4 GHz. If the router produces two Wi-Fi networks, one of them will be on that frequency.
Check a Microwave for Leaks Step 9

Step 3. Unplug the microwave

Unplug the appliance from the mains completely, as you will be placing your computer inside it, and the last thing you will want to do is accidentally turn on the oven.

Check a Microwave for Leaks Step 10

Step 4. Prepare the computer

Turn on your notebook and connect it to your local Wi-Fi network. Check the battery or display settings so the computer does not go into hibernation in the microwave.

Check a Microwave for Leaks Step 11

Step 5. Find out your computer's IP address.

You will need it to send a signal to your notebook. To find it, do the following:

  • On Windows: Open Control Panel. Enter Network and Sharing Center → View network connections → select your Wi-Fi network → click the chevron (>) to expand (if necessary) → View the status of this connection → Details. Look for the number next to "IPv4."
  • On Mac: Open System Preferences. Click Network, select Wi-Fi on the left and find your IP address on the right.
Check a Microwave for Leaks Step 12

Step 6. Place the notebook in the microwave. Not turn on the oven! You'll just see if its casing can block the Wi-Fi signal.

Check a Microwave for Leaks Step 13

Step 7. Send a signal from the other device

Open Command Prompt (on Windows) or Terminal (on Mac). Type ping, give a space and enter your computer's IP address. For example, type ping

Check a Microwave for Leaks Step 14

Step 8. Wait for an answer

If the ping is answered, the computer was able to pass the signal through the microwave door, which means the oven is leaking. If the time of packets expires, the microwave blocked the return of the signal. This does not guarantee that the oven is not leaking, as an operating microwave produces much stronger waves, but it is a good sign.

Microwaves can legally let a certain amount pass, which is considered safe. If your router is in the same room as the microwave or on the other side of the wall, just because ping works doesn't necessarily mean a dangerous leak. For an estimate, a router with a strong signal (-40 dBm) should be at least 6 m from the microwave

Method 3 of 3: Fixing a Leak

Check a Microwave for Leaks Step 15

Step 1. Check the seal around the door

Microwave leaks are often the result of wear or broken parts in the oven door. If you have encountered a problem, look for these common causes:

  • Cracks on hinges;
  • Worn areas or cracks in the seal;
  • Notches or broken parts on the door itself;
  • Broken hinges or doors that don't close well;
  • Damage to the door's metal mesh, especially holes larger than 12 cm;
  • A broken clasp that doesn't immediately turn off the oven when you open the door.
Check a Microwave for Leaks Step 16

Step 2. Take the microwave to technical support

These locations have access to much more accurate testing equipment. Technicians can confirm that your device is safe and identify the problem that needs fixing.

You may be able to convince the shop to lend the test equipment for a small fee, but these devices require calibration and training to use, so hiring a professional can yield more accurate results

Check a Microwave for Leaks Step 17

Step 3. Contact the manufacturer

If your microwave oven is leaking, especially if it is new and undamaged, contact the company that made it. You can also fill out a Consumer Accident Report on the Inmetro website, recording the occurrence of failures as an incident. This helps the agency monitor which products pose the most health risk and need regulatory attention.

You can also report the issue to consumer protection organizations or government health departments

Check a Microwave for Leaks Step 18

Step 4. Understand the danger

Microwave radiation is the same type emitted by visible light and radio waves, not ionizing radiation that can cause cancer or radioactivity. As far as is known, the only risk posed by a leaking microwave is due to the high level of heat it produces. It is more dangerous to the eyes, which can cause cataracts, and to the testicles, which can cause temporary sterility. Higher microwave levels can cause skin burns. If you do not experience any symptoms and stop using the leaking device, you are unlikely to suffer any long-term damage.


  • Recycle your old microwave. If you are donating it, clearly indicate in a note that you think the device is leaking so that the people who receive it can make the decision to repair or recycle it.
  • Some sites recommend placing a cell phone in the microwave oven and calling it to see if the radiation is leaking. But the leakage protection of these ovens is made specifically for the microwave frequency (2.4 GHz), and does not necessarily prevent other frequencies from passing through. Cellular frequencies are quite different, within the range of 800 to 1900 MHz, so there's no reason to expect your microwave to block them.


  • Do not turn on the microwave with the notebook inside.
  • Do not disassemble the microwave if you are not trained to do so. These devices contain a very high voltage magnetron (about 2000V or 0.5A), which can seriously injure or kill you if touched.
  • These methods are not failsafe and should not replace the judgment of a competent technician using suitable equipment.

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