The NEC (National Electrical Code) Handbook is nearly 800 pages long; a new edition is published every three years. That’s a lot of reading just to learn the standards for electrical systems.

Then you have to learn to do this stuff. An apprenticed electrician studies for two years and spends 8,000 hours on the job (about four years), just to earn the designation of Journeyman for his trade.

Why am I telling you all this? Because working safely with electricity requires knowledge and skill. There’s a lot to learn. And mistakes can be dangerous to your health. So my advice to you as you learn about your electrical system can be summed up in three words: proceed with care. If you are unsure or confused about anything described in this chapter, don’t hesitate. Call a licensed electrician to help with your wiring problem.

In this chapter, you’ll find a lot of information about household electrical systems, but only a couple of things to do yourself. Some houses have up-to-date electrical systems, and others are deplorably out of date. If yours is of the latter variety, I advise you not to work on it yourself. And even if you have a modern system, there are as many “exceptions to the rules” in wiring as there are conforming setups. To become well versed in wiring takes more space than there is available in this chapter.

I can’t see what’s in your house and behind your walls. If your equipment is thoroughly up to date, you can do a few things yourself, like change a light fixture or install a dimmer. Refer to the equipment instructions for those projects. But for more complicated projects, study a book that’s strictly devoted to household electrical systems. And don’t attempt things you don’t understand and are not comfortable with; call a pro.

Volts, amps, watts … aren’t they all the same thing? If you think so, you may be in a bit of trouble around an electrical panel. Let’s start by defining our terms.

Electricity is the flow of electrons through a conductor. In the case of your electrical system, the conductor is wire, which for safety is encased in a nonconductive sheath. The force with which the electrons move is measured in volts. The speed with which electrons move is measured in amperes (commonly known as amps). Output of electricity is measured in watts.

The electrical service that enters your home from the utility meter, and connects to the electrical panel, consists of two 120-volt “hot” (live) wires and one neutral. An old electrical system will have only one 120-volt wire plus the neutral, and is usually insufficient for most large, modern appliances. If you have the latter, it’s time for an upgrade.

In Chapter 4, I covered your home’s electrical power source—the electrical service panel. From this control center, the power coming into the panel is divided into branches of electrical current, which travel around your house along loops of wire, called circuits, that begin and end at the panel. Circuits are controlled by means of individual circuit breakers or fuses. Each breaker or fuse has a number—15, 20, 30—which represents the number of amps that a circuit can conduct. Large equipment such as clothes dryers, electric ranges, or air conditioners usually requires a large-capacity (= large number of amps) circuit to run, so each of these appliances usually has a circuit dedicated solely to its operation.

When a particular circuit breaker keeps flipping to “off,” or a fuse keeps blowing, sometimes the cause is too great a demand for electric current along a particular circuit. You will have to unplug some power-using devices (lights or appliances) to lighten the demand (also known as the load) on that circuit. If there’s another circuit nearby where you can safely plug in the additional items, your problem is solved. If you can’t solve the overload problem, or if that does not seem to be the cause of the blown fuse or tripped circuit breaker, you’ll need the assistance of a licensed electrician.

When you create a map of the circuits on your panel, which is the layout of your home’s electrical system, you will be able to see if the capacity of your electrical service is equal to or greater than the load. It’s good knowledge to have, and reassuring when you know you’ve got plenty of power. If your home is underpowered for all the equipment and appliances you want to use, you should make an electrical upgrade as soon as you can manage it. An underpowered system is dangerous.

First, look at your electrical panel; on most panels, each circuit breaker or fuse is numbered on the face of the panel. If yours are not numbered, you can do this yourself with a fine-tipped permanent marker. Starting with number 1 at the top left, put a number on the panel next to each breaker or fuse, sequentially.

You may notice that in some cases, two circuit breakers seem to be toggled together. These are the large capacity breakers for major appliances and systems. Their amperage (30, 40, etc.) is marked on the toggle.

If your electrical panel is equipped with circuit breakers, you will need to flip the breaker to the “off” position to shut off power to any location that is serviced by the circuit it controls.

To return power to the circuit, you’ll need to flip it back to the “on” position.

Remember, use one hand when you work at the panel. The other hand should be at your side. You want to avoid becoming an open circuit for any loose current!

When a fuse has blown, its center may look black (like the illustration below on the right) or the little lead strip in the center may look broken or melted. Either way, it must be replaced. Again, use one hand to remove/replace the blown fuse, with your other hand at your side.

The fuses shown can be removed and replaced with a fuse of the same amperage. This is important. One of the reasons that circuit breaker panels have pretty much replaced fuse panels is that many accidents and fires have been caused by the replacement of one fuse with another of a different, and thus incompatible, size. Circuit breakers are not necessarily safer than fuses. But the problem with fuses is that you need to have a supply of them, in all the right sizes, at all times.

Now, let’s get to mapping. You’ll need the following:

Once all of the circuits in your house are identified, it will be safer and easier to work with your home’s electrical system.

To find out whether your circuits are sufficient for what’s plugged in or wired to them, you can calculate the electrical load for each circuit. You’ll need the following:

Take your electrical circuit map, and on a separate piece of paper note the number of watts for everything that’s on a particular circuit. The wattage of light fixtures is the total wattage of the light bulbs in the fixture; three 100-watt bulbs have a load of 300 watts. Appliance wattage is often listed on the back or underside of the unit.

The formula for determining the maximum load is:

Or look at it another way:

So, if 15-amp circuit #1 has four 100-watt bulb fixtures and a radio (15 watts) for a total of 415 watts, divide that by 120 (= 3.4 amps) and you know there’s room on that circuit for a few more light bulbs and probably a television set.

But if you’ve got a toaster oven (1,400 watts) plugged into circuit #1, you’re getting very close to the limit of the 15-amp circuit’s capacity (1,800 watts). That circuit is near full, and so should not have other things plugged into it.

The proper load for any circuit is about 80 percent of its capacity. So, if you’ve got a 15-amp circuit, a load of about 1,400 watts is just right.

By doing these calculations for your system and what’s plugged into it, you’ll know whether or not your home is adequately powered.

If a licensed electrician has not checked out your electrical system in ten years, or you have just moved in, you might want the pro to have a look. He or she can tell you whether your electrical service is properly sized for the amount of electricity you are using, or plan to use. In the case of an old house, you may find that your house has aluminum wiring (you do not want to do it yourself with aluminum wires), or that the system is not properly grounded. Before you go beyond your mapping project, it’s good to know as much as you can about your system.

You might call them plugs (they’re not), or outlets (not quite right). The correct term for the little face-like electrical devices in your walls, where you plug in lamps and appliances, is receptacle. There are three basic types you should be able to identify:

A receptacle with two slots of equal size is nonpolarized. This type of receptacle is often found in old houses where the wiring has not been upgraded or grounded. If you have this type of receptacle throughout your house, you need to consult an electrician.

Polarization helps reduce the potential for shock. Most electrical devices and appliances have polarized plugs—one blade is wider than the other. Nonpolarized receptacles do not accept polarized plugs; these receptacles are outdated and should be replaced.

A two-pole, polarized receptacle’s slots are unequal in length; one is longer than the other. When a polarized plug is inserted in this receptacle (if it’s wired correctly), the wires in the cord connect to the corresponding wires in the circuit; the short slot is the “hot” side, the long slot is neutral. This receptacle accepts polarized plugs, but does not have a half round hole for a grounding prong. These receptacles are safer than nonpolarized receptacles, but not as safe as a grounded system.

A two-pole, three-wire grounding receptacle has all the right stuff, and accepts plugs for all modern electric devices except the special plugs used for large electrical equipment and appliances (ranges, dryers), which have matching receptacles for their large-capacity circuits.

If you have two-pole, three-wire grounding receptacles in your home, your system appears to be up to date. One way to check that the receptacles are grounded (other than calling the electrician) is to check them with a handy, inexpensive (around $3) device called a receptacle analyzer. This device will tell you at a glance if your receptacle is properly wired and grounded. The sequence of lights will alert you to any problems.

Amazing, but this little plug-in will tell you a lot about the wiring of any receptacle. Besides telling you that the receptacle is grounded and all the wires are attached correctly, it will alert you if …

The receptacle analyzer will also tell you if the wires are not connected properly.

In the bathroom, near the kitchen sink, outdoors, and in other spots where water may come close to electric power, the electrical code demands that GFCIs (ground fault circuit interrupters) be installed, instead of ordinary three-wire grounded receptacles. These receptacles, invented about thirty years ago, will shut down if the current level in the circuit changes even a tiny bit. This is important near water; if an appliance that’s turned on should fall into water or become wet and you touch it, the result can be a lethal shock.

GFCIs are useless unless they work properly, and they do wear out over time. Here how to test one; you should test every GFCI in your home every month. To do this you’ll need a lamp, plug-in radio, or voltage tester.

If a GFCI does not operate properly, it needs to be replaced.

Every so often, a light bulb will shatter, and you’ve got a very sharp problem on your hands. If the bulb is in a lamp, unplug the lamp before you do anything else. If the bulb is in an overhead fixture, you’ll need to turn off the switch that controls the bulb, and also, turn off the circuit breaker (or remove the fuse) that controls the fixture. Then you can proceed.

First, get out your work gloves; those shards of broken bulbs are extremely sharp. If you’re working above your head on a ceiling fixture, you’ll want to wear safety goggles, too.

You’ll need the following:

After removing as many sharp shard of glass from the bulb base with your gloved hands as you can, grip the bulb base with the ends of the pliers and try to work the bulb base out of the socket as you carefully turn it counterclockwise. This may take some deliberate, careful work; take your time and don’t try to force the base. If you can’t get the bulb base out, you’ll need to replace the fixture.

Many people have told me that you can use a half of a raw potato to remove a broken bulb; just stick the flat end of the potato onto the broken-off end of the bulb, and turn counterclockwise (after turning off the power, of course!). However, I’ve only been told this. I’ve never met someone who’s removed a broken bulb with a potato. When I do, I can confirm the effectiveness of this method.