Microwave Oven Testing
Microwave ovens are PAT tested like any other appliance, but they also need additional tests not always done in full, and not needed in all circumstances.
Where the oven is used for commercial purposes it should be tested for temperature rise, power and emissions leakage.
In addition to the PAT test, a microwave oven needs to be tested for the emissions leakage, which could come through a faulty door seal or lock, as an example, and the heating power – after all nobody wants undercooked food – it risks food poisoning, and you don’t want to do that to your staff or customers.
You may see an engineer waving his leakage tester in front of the oven whilst running it with nothing in it; this isn’t going to get the desired results and may result in damage to the oven. You don’t want to be paying for that.
Our microwave oven pat testing service is an add-on; we don’t do it automatically, only on request. If we feel you may benefit from it we will discuss it with you.
Microwave ovens use high frequency electro magnetic waves to cook the food. If these waves leak out they can result in serious burns to the user.
Microwave ovens are designed to keep the energy within the cooking area, however damage to the door, lock or seal can lead to excessive leakage.
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:
- BSEN60335-2-5 2002 Requirements for Microwave Ovens
- The Electricity at Work Regulations 1989
- The Provision and Use of Work Equipment Regulations 1998
You will receive a certificate confirming the microwave oven is safe
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.
- 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.
- Turn the microwave on at maximum power for one minute
- 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.
- Now we do this calculation: Final temperature minus initial temperature = Temperature rise
- 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!