Microwave Oven testing Silver and black with buttons

Microwave Leakage Testing

Microwave ovens, after prolonged use can get deteriorate and leak excessive amounts of micro-wave radiation; this affects human health.

A microwave that omits more than 5mW/cm2 at a distance of 50mm from the outer casing of the oven is omitting too much radiation and should not be used; so we use a micro-wave leakage tester to scan the oven (whilst it is in use) to check to see if these parameters are being met.

A microwave oven is also required to have two independent interlocking systems that stop the cooking process when the door is opened; we also check this is functioning correctly.

We carry out this emissions check when we do the standard PAT test on the oven; some companies charge extravagant amounts (approx £10) for this service which takes about 1 minute – we don’t charge that, we charge just the same amount as the quoted per item rate for your job.

How does a Microwave Oven work?

A microwave oven heats food through micro-wave energy; the food absorbs it during the cooking process.

The micro-waves penetrate the food causing molecules to vibrate against each other which produces heat. The micro-wave energy is safely contained within the oven unit by the metal cooking chamber that you put your food in. This acts, in principle like a ‘faraday cage’. When the door closes, the viewing window which contains a conductive mesh, acts to stop the waves passing through the door.

The seal around the door is further designed to form a cavity to absorb any stray radiation that is leaking out.

If any of these features are not intact they will not function correctly and micro-waves will leak out; which is why they are inspected during the checks that we do.

A rusty microwave, may become a microwave that omits too much radiation, just as an oven with a damaged seal will do too.

Is microwave leakage testing still required in the workplace?

Microwave leakage testing is a test that many years ago got linked to PAT testing because it was convenient. Most offices etc have food heating facilities, such as microwave ovens, so it made sense for the same person to carry out all the safety checks.

Considering that microwave leakage can pose an exposure risk to the user, which can lead to health problems, periodic testing shouldn’t be ignored.

British Standard BS5175 requires all types of microwave oven to be checked for signs of failure to include door seals, safety interlocking and the internal make up of the appliance.

For an independent view on getting microwave ovens inspected for emissions leakage check out this 2021 article on Health and Safety Today.

Contact us to arrange your electrical testing

Enhanced Microwave Testing

A microwave oven also can deteriorate over time functionally; it is designed to use a certain amount of power in order to reach the desired temperatures to heat food correctly, to eliminate the risk of not cooking the food correctly, which in turn may cause food poisoning. In a commercial kitchen this is a major danger, especially from the bad press the business may incur.

So, commercial overs should also be tested for temperature rise and power.

This process is time consuming and so additional costs are incurred to do this.

This process is only done on request; we don’t do it automatically as it requires specialist equipment to carry it out which our engineers do not carry in their usual tool kit.

Further information on microwave oven testing

According to a survey; 56% of microwave ovens used for more than 2 years can leak levels of radiation 10% higher than the safety standard of 5mW/cm² regulated by the FDA and EPA.

The functionality of commercial ovens can decline over time with constant use so it is still recommended that ovens be checked for power and temperature rise. 

Microwave oven emissions testing checks that the levels of radiation emitted from the machine are within recommended guidelines. The radiation limit is set to 5 milliwatts per square centimetre at approximately 5 centimetres from the oven. 

After time and use the door seals of an oven can wear down and become faulty, which affects performance of the oven.

We use appropriate equipment to ensure your oven operates in accordance with:

You will receive a certificate confirming the microwave oven is safe

DRA PAT Testing conduct microwave oven testing in Newcastle upon Tyne, Sunderland, Durham and across the North East

When it’s likely you need to replace your oven

Your microwave oven will not last for every and these are signs it could be due a replacement:

  • Your food takes longer than the expected time to cook; test it by putting a mug of water inside and running the oven for 2 minutes. If the water isn’t boiling hot now may be the time for a change
  • The door seal is damaged; modern ovens tend not to have seals, but on older versions that do, a damaged seal leads to excessive radiation leakage
  • The keypad doesn’t work as intended; if buttons are not responsive the functionality of the oven will be affected.
  • Rust inside; this usual refers to a lack of proper cleaning, and there is no way to fix it now – replace it
  • Smells; burning smells, smoke or sparks are a sign of a fault. Turn off the oven immediately, unplug it and dispose of it safely.  

Microwave Oven PAT Testing

When injury from exposure to microwaves occurs, it usually results from dielectric heating induced in the body, the same heating that cooks food.

Exposure to microwave radiation can produce cataracts by affecting the lens in the eye.

Exposure to heavy doses of microwave radiation (as from an oven that has been tampered with to allow operation even with the door open) can produce heat damage in other tissues as well, up to and including serious burns which may not be immediately evident because of the tendency for microwaves to heat deeper tissues with higher moisture content.


Test for Microwave emissions leakage

It is important to check the microwave oven for leakage when the oven is in use, which is quite easy to do using a calibrated Microwave Leakage Checker.

To do this a mug of 300ml water is placed in the microwave oven which is then put on maximum power for a minute. Using a Microwave Leakage Checker the engineer scans the door seals and the front glass. This will indicate if the level of radiation leaking out is within an acceptable safe level of 5 mw/sq. cm.

Microwave ovens are designed to switch off instantly as soon as the door is opened, through the inter-lock system; this should be checked during oven function tests.

It is recommended but not essential that the oven is labelled to show that both the leakage and the interlock tests have been carried out. We actually have had feedback from clients that these labels are quite messy and obtrusive, so we don’t put them on the sides, only the rear of the oven. 


Testing for Heating Power

As a microwave gets older it’s not going to deliver the power you expect it to deliver; that 900w oven won’t stay 900 watts for ever. But have no fear, it is quite easy for us to check the rated power output of the oven by following this fairly simple process.

  1. Fill a plastic measuring jug or beaker with with 3ooml of tap water, measure its temperature and place it on the tray inside the microwave oven.
  2. Turn the microwave on at maximum power for one minute
  3. As soon as the microwave stops, open the door, give the contents of the jug a brief stir using a thermometer, then take a temperature reading of the heated water. 
  4. Now we do this calculation: Final temperature minus initial temperature = Temperature rise
  5. Then, we need to estimate the microwave heating power by multiplying the temperature rise by 4.2 X (vol in ml) divided by the time (in seconds) to get the microwave power (watts)



Checking the microwave oven yourself

Users of ovens should be aware of potential problems. Your staff should be asked to report any obvious signs of damage to the microwave oven when they spot them and stop using it immediately to prevent any further risk. If there is a noticeable drop in power for example, such as when food takes longer to heat than expected, this also should be reported.  

Top Microwave Oven Tip

If you are using a domestic oven at work it is never going to last; it will get damaged quickly, it will rust quicker than you expect and it probably will breakdown. 

The microwave is intended to save time and energy on tasks such as cooking and reheating, but they have a relatively short lifespan when compared to other common kitchen appliances, and that is assuming they are used as intended, which at work they rarely are. 

The average microwave oven lasts about five years with normal use, in the home, but a lot less with heavy use and poor maintenance, which is more likely at work. At work it is not uncommon for a microwave to last less than a year. 

We have seen many domestic ovens in use in staff canteens, even restaurants, and the owners are complaining that they’ve had it less than a year and it is already in need of replacing. Yes – it is intended to may be be used once a day not a hundred times a day!