During these cold weeks, a hot fire is nice. But it needs to be in a fireplace. Destructive house fires are common right now, and the reason often reported is “faulty wiring.”

Homeowners can do a lot of prevention without the need for electrical training. Easiest to detect are overloaded power outlets. If there are several multiplier plugs drawing current from one outlet, they could be putting too much load on it. A standard household outlet handles 15 amps. Generally speaking, that’s the “strength” of the current flowing. Appliances and light fixtures are rated in watts, the “amount” of power they consume.

Without formulas and instrumentation, here’s a good rule of thumb measure: Add up all the watts of the items that are plugged into an outlet. Don’t treat its two receptacles separately; they feed off the same wire. Then divide it by 100. If it adds up to more than 15, you’re overloading the outlet. For example, a space heater consumes 1,500 watts at full power. Physics teachers will argue that it doesn’t quite run 15 amps, but we’re trying to leave some safety margin here: 1,500 divided by 100 is 15, so that space heater shouldn’t share the outlet with anything else.

Computers, lights, etc. have their wattage listed on a little plate. If only amps are shown, just use that figure for our rough estimate here. Several lamps, plugged in together with a refrigerator and maybe a heating strip to keep pipes from freezing, could overload the outlet and cause a meltdown. This often happens gradually, going unnoticed until the box in the wall is on fire.

To see if an outlet has been overloaded, inspect the slot on the left (the taller one). That’s the neutral. Burn marks or worse, melted plastic, indicates overloading. The outlet needs to be replaced and used with a lighter load in the future.

If you find some adapter in there, compensating for the lack of a round hole below the slots, the outlet isn’t grounded. That type has been prohibited by code for many years, and a licensed electrician needs to inspect the house system as soon as possible.

Another easy test is to click the “test” button on outlets that have one. These so-called Ground Fault Circuit Interruptors are found in modern kitchens, bathrooms and garages. If no loud click is heard, the GFCI outlet may be faulty.

Rudi Kiefer, Ph.D., is a professor of physical science and director of sustainability at Brenau University. His column appears Sundays and at gainesvilletimes.com.