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If you are asked to check a microwave oven, you should be testing it for Electrical Safety and also for Microwave Leakage. According to recent guidance, you should not be declaring it ‘safe’ unless it has had the microwave leakage test carried out. Note this is not the same as the EARTH LEAKAGE test carried out by the PAT Tester.

The procedure for checking microwave leakage is not difficult, but you will need a special microwave leakage tester – these are available from www.yotari.co.uk and other suppliers, and cost approx £40 - £50.

If you are testing commercially, you should be able to charge approx £4 - £5 per test, so the device will pay for itself very quickly.

Make sure the tester is working accurately – you can get it calibrated although it shouldn’t need it when new – look after it and replace the batteries regularly.

You can also purchase special labels, to indicate that the microwave has been tested for Electrical Safety and Microwave Leakage.

• Check the outside of the microwave for damage – check carefully around the door seals and hinges.
  
  
• Carry out a full inspection and electrical test. Do this before the microwave leakage test (and do not carry out the microwave test if the appliance fails on the electrical test.)
  
  
• Note that it is common for microwave ovens to have an insulation resistance of approx 10MΩ, rather than ‘infinity’ found on other appliances. This is normal – as long as the value is greater than 1MΩ the appliance passes the insulation test.
  
  
• Fill a cup or glass with water and place inside the microwave
  
  
• Manually check the door seal to see if there is any damage, or any food remnants which could interfere with the seal. Fail if the seal is damaged or badly contaminated.
  
  
• Set the microwave going – if it has several power settings, set it to the highest.
  
  
• Hold the microwave tester away from the microwave and switch it on. Follow the manufacturer’s instructions to ‘zero’ the device.
  
  
• Keeping the microwave tester on, run the tester along the door seal and hinges. If excessive leakage is detected, the tester will beep. The occasional very short beep (less than half second) is ok but otherwise any significant beeping will indicate excessive leakage. Check the instructions for the exact procedure - this varies slightly between devices. Switch off immediately in the case of excessive leakage and fail the microwave oven. Make sure you go all around the seal (including underneath if you can) and check all hinges and fasteners.
  
  
• Final check – whilst the oven is operating, open the door and check that the interlock is working – the heating should stop immediately that the door is opened.