Appliance Self Repair Advice
Basic Electrical Safety
- Created: Saturday, 30 October 2004 00:35
- Last Updated: Monday, 01 August 2016 10:03
- Hits: 18323
Staying Safe Working On Appliances
Stay safe, stay alive!
It's all too easy these days to take all our electrical appliances- and what makes them work- for granted. But, make no mistake, hidden inside your washing machine, dishwasher, television, computer even, there is a killer just waiting for a chance to strike.
Here is a guide to basic electrical safety, things you could check yourself.
The first place to start is the plug.
Switch off at the socket and remove the plug. Look at the general condition of the plastic moulding, if it is cracked, broken or loose in any way it should be replaced. Check the pins. The metal parts should be clean and not burnt and the plastic at the base of the pins should not show any sign of burning or melting. The two conductor pins should be of the shielded type, this means the first centimetre or so should appear to be plastic. This is to prevent fingers coming into contact with the pins as the plug is being removed and if your plug is not of this type it will be of significant age and should be changed. Don't be fooled by the age of the appliance as we all a have a drawer somewhere in the house with a load of old plugs in and it is not unusual to find a 20 year old plug that someone has fitted to your new high tech dishwasher.
Don't forget to also have a quick look at the socket the plug was plugged into, if there is any sign of burning around the sockets then this HAS to be replaced along with the plug but you will need an electrician to carry that out.
Now all new electrical appliances should have plugs already fitted. Often these are a moulded on type i.e. they are specially made with the lead permanently fitted. The most obvious way to tell if a plug is this type is the lack of any screws. Although you will be able to remove and replace the fuse, there is no other maintenance you can carry out on these and no attempt should ever be made to open one up. If the plug is damaged or burnt, it will need to be cut off at the lead close to where it emerges from the plug and discarded. Always unplug it before cutting it off and afterwards remove the fuse before throwing the whole lot away, as, if it were to be plugged in again, the bare wires at the cutting point would be live and extremely dangerous.
To Fit A New Plug
Open up the new plug. Each of the three pins will have a screw terminal into which the bare conductor of each wire needs to be connected. There are several differing types of these but most are of the hole and screw down type where the wire is poked into the hole and the screw above is tightened down to secure the wire and make a good connection. Other types involve wrapping the bare conductor around a threaded pin onto which a nut is screwed which is tightened down to secure the lead.
All UK plugs will have 3 pins: Live, Neutral and Earth. Most domestic appliances we deal with on this site will have three corresponding leads. Other appliances may only have 2 leads that will only be connected to the Live and Neutral pins.
Also in the plug will be a fuse (see below) and a gripping device to prevent the lead from being pulled out of the plug. This will be either of the 2 screw type which clamps a cross piece across the lead to secure it or a screwless type in which the lead is wedged in between 2 clamping pieces. It is important that the outer cover of the lead is held in the clamp rather than the individual wires- keep that in mind when stripping off the outer covering.
Using wire cutters or a knife, carefully remove the outer covering of the lead from about 5cm from the end of the lead. Be sure not to damage the insulation of the individual wires while doing so, if this does happen, cut the lead at the point of damage and start again.
You will now have 3 individual leads coloured brown, blue and green/yellow. Lay these across the open plug back with the end of the outer covering in position over the clamping device. This will enable you to gauge how long each of the individual leads should be. Starting with the green yellow lead, cut it off leaving just enough for it to reach and be inserted into its pin which is the earth pin on its own at the top of the plug. Do the same for the brown lead that goes to the live pin where the fuse is and also the blue, neutral wire that will be the lower left hand pin. All these pins will be clearly marked E (earth), L (live), N (neutral).
Once the leads are of the correct length, bare off enough of the coloured insulation for each lead to fit into their respective screw terminal, twist the now exposed copper strands together and either poke this through the hole or around the pin depending on type of plug. It is important that none of the copper wires are protruding from the pin and that the screw is tightened down onto to copper wires rather than the insulation.
Next, secure the outer lead to the gripping device as per the type of plug you have. Then fit the fuse ensuring it is the correct rating for your appliance. Before re fitting the plug cover, take one more look to ensure each lead goes to the correct terminal, no strands of copper wire are straying and that the fuse is correctly fitted:
Ensure the plug has the correct fuse fitted. Most domestic appliances should have a 13amp type, exceptions being cooker hoods and gas hobs, which will be either 3 or 5 amps. The rating of the fuse will be written on it. Always check the instruction manual for your appliance to see which fuse you should fit and never replace a blown fuse with anything other than the correct item. The fuse is there for your protection should a fault occur. If you find your fuse is blown, there is normally a reason for it, if your replacement fuse also blows then you will need expert attention and continually replacing a blowing fuse may be dangerous and cause further damage to your appliance.
While the appliance is un plugged, have a good look at the mains lead, ensure the outer covering is not broken or split and none of the coloured inner wires or even the copper conductors themselves can be seen anywhere along its length. If so, the lead will want changing and this is often not as easy as it may appear due to termination and clamping of the lead inside the appliance and should be carried out by an experienced engineer only.
If you find your appliance lead is too short, then the best and safest option is to have it replaced by a longer item, your local appliance engineer will be able to do this. Do not be tempted to join another piece of lead to your existing lead under any circumstances. Although there are several joiners available, the high current a tumble drier, for example, draws means that this is not an option.
If you must use an extension lead, make sure it is of high quality, rated for the appliance concerned, is as short as possible and not coiled up. Beware as many extensions leads available for computers etc are not rated high enough for a domestic appliance and also throw out any home made extension leads as these are often unsafe, 2 core types.