Electricity is a pretty dangerous thing however we all have lots of it coursing through our homes and we use it perfectly safely. This is because of several design features built into our homes that alert us to faults and protect us from their effects. Essential parts of this safety system include the plug, the fuse, the main switch the fuse box and in modern properties, Residual current devices (RCD). You need to understand what each of these things does, how it should work and what possible sign are danger are.
We will be writing a series on domestic electricity that will cover each of these areas. Initially you need to know a bit about what electricity is, how it travels and what the dangers are – so read on.
Electricity provides a way to transfer the energy generated in power stations to the appliances in our homes. These appliances use power in different ways; hi-fi’s use it to vibrate speakers, washing machines use it to turn their drum and ovens to heat their elements.
Electricity can only travel through some materials – mainly metals. In the center of all those plastic power cables is a metal core, usually copper which the electricity can travel along.
Electricity can not travel through plastic and rubber so it is used as a barrier to stop electricity flowing where we do not want it to. That is why power cables are coated with plastic or rubber.
We say that an item is ‘live’ if electricity is passing through it and a live item is potentially dangerous. If you unplug an item it will not be live. If you turn off a plug socket anything connected to it will not be live. But if you turn off a power button on a device parts of it can still be live.
Electricity can travel through water and our bodies. If it passes into our bodies it gives us an electric shock. The severity of the shock depends on how much electrical current is flowing. Mild shocks will just feel fuzzy or warm, severe shocks can cause heart problems, burns and death. Mains electricity (the electricity passing around our homes) is powerful enough to cause serious injury and death.
So how might we get a shock?
1. Sticking a metal object into an appliance. Ever stuck a knife in a toaster or a screwdriver into something? If you hit a metal part of an appliance with a metal object the electric current can flow straight into your hand. NEVER WORK ON AN APPLIANCE THAT IS PLUGGED IN, THAT INCLUDES YOUR TOASTER. If you really can’t be bothered to unplug your toaster before you try to get the bread out – use a plastic or wooden implement not a metal one.
2. Errors in the appliances can cause internal parts to move and wires to come loose. This can make parts of the appliance live that you would not expect – like the metal case. That means just touching your appliance could give you a shock. If you experience a shock or a strange warm static sensation when touching an appliance it is likely it has a fault and you should un-plug it and get it checked out immediately. Note that the fuse in a plug and earth wire (see later), if properly fitted, should protect you from a dangerous shock.
3. Dropping an electrical item into water. Electricity travels through water really easily – if you drop an electrical item that is plugged in into water the current will flow into the water and anyone who has their hand or body in the water. For the same reason plugging in and moving live appliances with wet hands is dangerous.
1. Overloading a socket. Plugs, adaptors and extension sockets should not feel warm or make a buzzing or crackling sound and they certainly should not show signs of soot or burn marks. If see any of these signs unplug everything and wait until the plug has cooled down. In future plug less items into the socket. Electrical faults cause 50% of all house fires so the risks should not be underestimated. If you don’t have enough sockets then you must get a registered electrician to fit more. Things like heaters, kettles, hair dryers and washing machines draw a lot of power so they are not good appliances to share sockets with other appliances.
2.If the external plastic casing of an electric cable becomes damaged the wires inside can be exposed. Anyone who touches the damaged area could receive a dangerous shock. If you find a damaged cable unplug it straight away and replace it.
3. Repairing or maintaining appliances while they are plugged in. You don’t know which internal parts of an appliance are live, parts that should not be live may become live due to faults. Do not open the cases to appliances including changing the bags and filters in vacuum cleaners while the appliance is plugged in.