How to check and replace mains plugs and fuses

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    13A plug topEvery new appliance sold in the UK should be supplied with a 13 amp electric plug connected to it, unless it requires hardwiring (usually high-current devices like electric cookers and electric showers).

    Most of these appliances may come with a moulded plug that can be replaced if damaged.

    In this article we will show you how to replace a 13 amp plug and how to select the correct fuse for the appliance.

    Firstly, the description of a plug as '13A' or 'thirteen amp' denotes the maximum current that this type of plug is designed to be capable of using continuously; in most cases the plug will not have a thirteen amp fuse fitted unless the appliance requires it.

    The current used by a device depends upon the amount of work the appliance is doing. The current is highest in appliances designed to produce heat, so kettles, irons, toasters and heaters usually have a high current fuse.

    To identify the correct fuse for an appliance check its rating plate. This is a label that will usually contain the model number, the appliance voltage (for example, 220-240 volts) and the power (e.g. 2kw or 2000 watts). In this example the power (2000 watts) divided by the voltage (240volts in the UK) gives a current of 8.33 amps - the closest plug fuse value to be able to pass this current without failure would be a 10 amp fuse.

    When some appliances are first turned on, the current may peak much higher than the running current (for example , in fridge motors). In these instances the manufacturer may advise a larger fuse be fitted but this should always be replaced by the same type of fuse.

    Fuses are commonly available in the following sizes:

    2 Amp: Suitable for up to 480 watts (black markings) and used in low power devices like radios and shavers.

    3 Amp: Suitable for up to 720 watts (red markings) and used in low power LCD televisions

    5 Amp: Suitable for up to 1200 watts (black markings) and used in some vacuum cleaners

    7 Amp: Suitable for up to 1680 watts (black markings) and used in medium power devices including larger vacuums

    10 Amp: Suitable for up to 2400 watts (black markings) and used in some heaters and large motors, including those in pressure washers

    13 Amp: Suitable for up to 3000 watts (brown markings) and used in high current devices such as kettles, toasters and heaters.

    The large amounts of power which high current appliances use can cause cables to get warm, so it is recommended that extension leads or adaptors are not used with these appliances, as it can cause heavy damage and even fires.If using an extension lead with a pressure washer or lawnmower for more than a few minutes, the lead must be unwound during use to allow the heat to dissipate.

    It is worth checking plugs for signs of damage from heat; this usually shows as browning or melting of the live or neutral pins. If there is a moulded plug supplied with the appliance the problem is likely to have been caused by a loose adaptor or socket where the plug was connected. The plug on an appliance is designed (if fitted in a proper socket) to supply the power required for the appliance but loose connections in adaptors and worn or substandard sockets will allow heat to occur from the connection resistance. On high current items used for long periods (fan heaters or tumble dryers) this may burn the plug.

    Check all non-moulded plugs in the home have the correct fuse fitted, do not have any loose connections and have cables correctly held in place by the cable grip across the outer cable cover.

    If when replacing a plug it becomes necessary to cut the cable's outer cover, take care not to damage the inner cable insulation. To prepare the inner cables trim off the insulation from the top 5mm of cable wire and then twist the cores together before firmly screwing into the plug pins.

    Cut the earth wire 5mm longer to ensure its the last to disconnect helping safely earth the appliance.

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    * All information provided is a guide only. BuySpares accepts no liability for any problems occurred while attempting any advice shown. If in any doubt contact a qualified repair service.