Sometimes, when you plug an electrical appliance into an outlet, you may notice a small blue spark. In most situations, this is a normal event as the electrons begin to flow into the appliance's power cord. At other times, however, a spark from an electrical outlet could start a fire or severely damage the plug. It is important for homeowners to understand why an electrical outlet may spark or short out without warning.
The electricity that powers a home comes in through a supply line connected to the main electrical grid. In countries like the United States, this supply line carries electricity at approximately 115 to 240 volts, with an average frequency of 60 hertz, or 60 cycles per second. In other words, the electricity flowing through the circuits of your home is running very fast and hot. Ideally, it should flow through the circuit and back out to the main grid without much interruption.
The electrical outlets in your home essentially tap into this fast-moving electrical stream and divert some of the electricity to whatever you plug into them. The electricity runs through one slot of the outlet, powers the appliance, then escapes through the second slot of the outlet. Any spark you may notice on the 'hot' side of the outlet is usually caused by the appliance's sudden draw of amperage. Once the electrons begin to flow, the spark dissipates, much like static electricity.
Once in a while, however, the relationship between the outlet and the two circuit wires becomes problematic. Electrical power can also cause heat energy, and this excessive heat can cause the insulation around wires to melt away. Once an electrical wire becomes exposed, it can come into contact with the metal casing of the outlet or even with the other circuit wire. If a connection is made, electrons leap across the gap and form a visible spark. Since the connection shortens the intended distance of the circuit, it is frequently called a short or short circuit.
A short circuit caused by overheated wiring can not only cause an outlet to spark - it can also create the ignition source for a dangerous electrical fire. Ideally, any short circuits should trigger a breaker switch or overload a fuse within a few seconds. Once the circuit has been broken, the electricity should stop flowing and the risk of fire should be reduced. If the household wiring is faulty, however, the entire circuit could overheat and create a fire behind the walls. This is why homeowners need to watch for any spark from their electrical outlets, particularly when running a number of appliances on the same circuit.