Wednesday, 20 August 2014
PAT Testing Electric kettles and other kitchen appliances
A variety of electrical appliances are in use in a normal kitchen. This chapter deals with PAT Testing of these - This is an extract from the PAT Testing Handbook published by First Stop Safety and available on Amazon
All electric kettles tend to be of Class I construction (Fig TE 1.1). This can easily be confirmed by a quick look at the rating plate which should confirm the absence of the double box symbol. With the power required to boil a cup or more of water, kettles are normally rated well above 1000W, thus requiring a 13A fuse in the plug.
Figure TE 1.1: Kettle
The normal Earth point for a kettle is the element. Just clip the Earth test lead to the element to complete the circuit for the Earth Continuity test. If there is a lot of scaling evident then this can cause the test to fail. An easy way to get rid of this and get a good connection to the element is to twist the crocodile clip round so that the teeth clean up the joint.
There is no need to make sure that the kettle is completely dry. Just empty the kettle. A few drops of water left in the bottom will not cause any problems during this test. For the Earth Continuity and Insulation Resistance tests just make sure that the kettle is switched on.
Cordless kettles can tend to fail the Earth Continuity test if there isn’t a good contact with the base unit. Make sure you push down hard on this during the test. If the kettle has a flat plate element, then either use a different test probe or fasten the crocodile clip onto a screw driver and use this to make a connection to the plate.
Food processors, blenders, mixers and juicers
These types of appliances (Fig TE 1.2, Fig TE 1.3) usually have a plastic enclosure and are of a Class II construction. This can be quickly confirmed by the double box ( ) on the rating plate. If this is the case, they will usually have a two core power cable as well.
Figure TE 1.2: Blender
Figure TE 1.3: Mixer
Testing these is quite straightforward as one doesn’t have to spend a lot of time looking for an Earth connection. Just make sure that the test clip is connected to any metal part and the appliance power switch is in the ON position during the test.
Toasters, sandwich makers, bread-makers, slow-cookers and rice cookers
As these are heating devices (Fig TE 1.4, Fig TE 1.5) they usually have a large amount of metal and are of Class I construction. This can be confirmed by the absence of the double box on the rating plate. Power rating can vary from a few hundred watts to more than 1000W. As they are Class I devices, a bit more care is needed when testing in making sure that one finds a good Earth connection.
Figure TE 1.4: Slow cooker
Figure TE 1.5: Sandwich toaster
For a toaster an Earth connection is easily obtained on the metal grills that hold the bread in. For the test, the toaster needs to be switched on. As there is no bread in the toaster, this will have to be kept down during the test.
Sandwich makers usually are of a plastic coated metal construction and Teflon coating over the heating surfaces will make access to any metal difficult. However it is usually possible to get a good Earth connection at the hinge point where the two halves of the sandwich toaster are connected.
In other heating devices such as bread-makers, slow and rice cookers, it is fairly easy to find a good Earth connection on the large metal surfaces inside the appliances.
Fridges, freezers, washing machines and dishwashers
All these types of white goods (Fig TE 1.6, Fig TE 1.7) are of Class I construction due to the large amounts of metal used in their construction. Power consumption can vary from a few hundred watts for a fridge up to 3kW for dish washers.
Figure TE1.6: Fridge
Figure TE1.7: Washing machine
An Earth connection is usually very easy to find due to the abundance of metal. Just avoid any plastic coated or painted parts. If you have to connect to one of the painted side panel, then the fixing screws usually provide a good Earth connection.
Generally kettles and other appliances that heat water or food tend to be rated at over 1000W, of Class I construction and have easily accessible Earth points. Kitchen appliances with motors in them will be typically of Class II construction, low power and made of plastic.