Microwave Leakage Testing
We offer Microwave Leakage Testing for FREE as part of our PAT testing service. The latest IET Code of Practice (4th Edition), no longer stipulates that Microwave Leakage Testing be carried out but we believe that it is an integral part of any safety check and so we will continue to offer it for free whilst others may not.
Microwave ovens use microwave radiation to cook food. Microwaves, like visible light, are a part of the electromagnetic radiation spectrum. They are extremely high frequency radio waves. As the frequency of radiation increases, its wavelength decreases, so very high frequencies correspond to very short wavelengths; hence the name microwaves. Microwaves may either be reflected, transmitted or absorbed by matter in their path. Metallic materials totally reflect microwaves. Most non-metallic materials such as glass and plastics are partially transparent to microwaves. Material containing moisture, such as food and even people, absorbs microwave energy. If energy is absorbed at a rate greater than the rate at which the material loses energy (i.e. rate of cooling), its temperature will increase.
In Microwave ovens, the microwaves penetrate the food or liquid and agitate the water molecules within. This causes molecular friction, which produces heat and results in a rapid rise in temperature. Cooking time is usually much shorter than in a conventional oven. The rate of heating depends on the moisture content, shape, volume and mass of food present.
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What are the health issues of Microwave exposure?
Exposure to sufficiently high levels of microwaves will cause heating. In the case of human tissue, excessive heating could have serious health effects such as deep tissue burns and hyperthermia.
Microwaves generated in microwave ovens cease to exist once the electrical power to the magnetron is turned off (like visible light from light globes). They do not remain in the food when the power is turned off. Neither can they make the food or the oven radioactive. Therefore, food cooked in a microwave oven is not a radiation hazard.
All microwave ovens have at least two safety interlock switches which stop the generation of microwaves immediately the door is opened. The design of modern microwave ovens is such that the microwaves should be contained within the oven, but it is still possible for some leakage to occur around the doors of certain microwave ovens. Generally, the required design of oven doors should restrict this leakage to a level well below that recommended
The Standard specifies a test to assess the level of microwave leakage and states that 'The microwave leakage at any point 50 millimetres or more from the external surface of the appliance shall not exceed 50 watts per square metre'. This Standard applies to ovens designed for domestic applications, even if used in a workplace. The recommended limit is conservative and includes significant safety factors, so that even leakage levels appreciably above the limit will have no known effect on human health.
Our own testing done during the course of PAT Testing have shown that microwave oven leakage levels in excess of the recommended limits are rare and an oven in good condition and used correctly is safe. If an oven appears damaged, it should not be used until a suitably experienced technician has tested the oven and checked that the leakage does not exceed the recommended limit.
"Routine testing of microwave oven leakage during PAT Testing is a valuable tool for peace of mind, and we include this service for free as part of our PAT Testing service"
Inspection by the user
The easiest way to ensure that your microwave oven is safe, is via user inspections.
A microwave oven should only be used if an inspection confirms all of the following points.
- The surface of the door is not damaged.
- The door fits squarely and securely and opens and closes smoothly.
- The door hinges are in good condition.
- The oven is clean and in particular the door edges and interior surrounds are not covered with food or burnt material.
- No corrosion is evident on the door, the door hinges or the oven interior.