How can you inspect a home’s electrical system if you know nothing about it? Believe it or not, you aren’t expected to be an electrician. And you can learn what you need to know about inspecting it.
This is a confusing subject, and it’s a potentially dangerous one, too, since most of the system is hidden inside walls. But once you know some of the basics, the rest is much easier to understand.
How Electricity Gets Into the Home
Electrical service comes from the provider – the utility company – and the provider’s responsibility ends at the service point or service drop. On most houses, the service drop is high on the house, where power lines run in from the main utility pole and down through conduit into the electric meter.
If the house has underground lines, there won’t be a visible service drop. In those cases, the lines run up from the ground into the bottom of the meter. Meters are usually close to the service entrance, which might be a breaker box or fuse box, and have a ground line driven into the soil. Often the meter and the box are on opposite sides of the same wall, but the meter can be a few feet away in some locations.
Next comes the breaker box or fuse box. That’s where electricity is distributed through separate circuits to different parts of the house. Each breaker or fuse inside the panel represents and controls one circuit. Breakers that look like two joined together are double-pole breakers, and run more powerful 220v circuits such as those for an electric clothes dryer. A fuse box has two separate 30-amp fuses for 220v circuits instead of one double-pole breaker.
Wiring Gauges for Different Jobs
Just as there are different types of breakers in the box, there are different gauges of wire for different jobs. The smaller the gauge the lighter the job, which means the wire for a dryer circuit is much heavier than that for a living room outlet.
A 20-amp circuit uses 12-gauge wire, and 14-gauge wire is used for 15-amp circuits. Those are the most common in any house. You’ll find 14-gauge in the better part of most houses, while 12-gauge is found in kitchens and other areas such as bathrooms and sometimes laundry rooms.
Heavier-gauge wires, which are commonly 6, 8 and 10, are reserved for kitchen ranges, air conditioning units, dryers and other major appliances. You might find heavier wire on a lighter duty circuit, but most electricians avoid that. Thicker wire is harder to work with. Conversely, smaller-gauge wire on a heavier duty circuit is a fire hazard.
Special Outlets and Breakers
You’re probably familiar with GFCI outlets. Some people, even electricians, shorten it to GFI. GFCI means Ground Fault Circuit Interruptor, and these are found in wet areas such as kitchens and baths. They protect against shocks and electrocution.
AFCI means Arc Fault Circuit Interruptor, and the Federated Rural Electric Insurance Exchange says it guards against fire.
You might see GFCI outlets at every point in a kitchen, or you might see only one. In some locations, one GFCI outlet is allowable to protect an entire circuit. If it trips, the whole circuit loses power. AFCI devices might be outlets or circuit breakers. In most locations, all bedrooms are required to have AFCI protection.
Identifying Old Work
All new wiring jobs are required to meet current electrical code, but that doesn’t mean outdated wiring is a code violation or that it’s unsafe. You’ll probably never know when a wiring job was installed, so all that you can do is report on its current condition.
Even knob-and-tube wiring was safe in its day, but Old House Web Inspector says any house that still has it is probably at risk just from degradation of the system. Add to that the possibility of new wiring tied into old knob-and-tube, and you could have the recipe for an unsafe system. Attics are a great place to spot old wiring, since the rest is hidden.
Outlets are another indicator of old work. Modern household outlets with a ground are 3-prong, and older outlets are 2-prong. With a 2-prong outlet, there is no ground wire. But not all 3-prong outlets are safe or grounded, either. A homeowner might have swapped out old for new without grounding the outlet, rendering the safety of a 3-prong useless.
There’s a lot to learn about the electrical system in any home, and this information just skims the basics. But if you start out with a good understanding of how home electricity works and which clues indicate possible trouble, you’ll have a good foundation to build on.
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