According to government statistics the average American home is 23 years old. Thus, most of us don't have the latest technology in electrical wiring in our homes. This doesn't mean we're in jeopardy. Old wiring doesn't have to be dangerous. Electrical circuits are usually safe as long as they aren't overloaded.

If you're using several new-fangled appliances all at once that weren't originally built into your home (electric exercise machines, a microwave, etc), you could, unknowingly, be overloading your electrical system.

Fuses in power panels are placed between the power source and the lights and plugs as a safety measure to prevent wiring from overheating when shorts and overloads occur. But when a fuse burns out repeatedly, it's a warning that something isn't right in the circuit, or that too many appliances are being used at the same time usually the latter. In either case, regularly overloading a circuit can wear out the wiring and make it dangerous.

As electricity passes through, wire molecular movement occurs. The more electricity used, the more molecular movement in the wire. This movement causes friction in the wire and resultant heat the more movement, the more heat. In a light bulb, lots of electricity is fed through a little wire (the filament), and a red-hot result occurs. Imagine the electric wiring in your walls in the same way as you do the filament in a light bulb.

When overloaded, a fuse usually burns. Before that happens, however, the wire between the appliance and the fuse overheats something like the filament in a light bulb.

Each time the wire in the wall overheats it becomes ever so slightly more brittle. As it becomes more brittle it becomes more resistant to the flow of electricity and therefore even more prone to overheating. Eventually, an old wire that has been regularly overloaded gets fatigued and can become a real danger. Remember: Taxing an electrical circuit can eventually wear it out.

It's easy to find out if you're overloading your electrical system. All the information you'll need is in your home and this column.

Since several plugs and lights generally are wired together on the same circuit, the first thing is to find out which are connected to which fuses (or breakers). By doing this you can determine how much power is available where and utilize that information to regulate use of the circuit.

First, draw a one-line plan showing each room of your home. It doesn't have to be fancy or to scale, but should show every plug and light location. Switches don't count, but include outside lights and plugs and the ones in the garage. Once the plan is complete, remove one fuse from the power panel (or switch off one breaker). Next, check every light and plug inside the house and out to find all those lights and plugs that have become inoperative (use a small table lamp to check the plugs). Mark them on the plan circuit 1. Repeat the procedure with every fuse in the panel, giving each circuit a different number.

Follow the procedure even if the fuse is marked for use by one appliance only. Fuses that are marked for a single appliance but provide power to other locations could signal a dangerous condition. If that is the case, call an electrician.

Once each circuit has been completely mapped out, the rest is easy. Remember this simple rule: Volts times Amps equals Watts. Here are two examples of the rule: 1) If the circuit is 110 volts and the fuse is 15 amps then the circuit will handle 15 x 110 or 1650 watts. 2) A 110 volt circuit with a 20 amp fuse will handle 20 x 110 or 2200 watts.

Caution: Using a larger fuse to get more wattage on a circuit is not the answer and is extremely dangerous. The size of a fuse in a circuit is determined by the size of the wire in that circuit. Using a larger fuse without changing the wire in the walls is foolish and deadly. Don't do it!

Let's say you've determined that a 1650-watt circuit in your home has 300 watts of lighting on it and three empty plugs. This means that when all the lights are on at the same time, up to 1350 watts of power is left to be shared by the three unused plugs. Hence, it would be a mistake to plug a 1500-watt hairdryer into any one of the three plugs at the same time that all the lights on that circuit are on. Why? Simple math 300 watts used by the lights plus 1500 watts used by the hair dryer equals 1800 watts of total power draw on a 1650 watt circuit. A 150-watt overload!

No wattage is used by an empty plug or when a light is turned off. Every electrical appliance is rated by wattage, and the wattage used by a light fixture is exactly equal to the total of the wattage marked on the bulbs screwed into it (three 60-watt bulbs equals 180 watts of load).