Four-Way Switch

A four-way switch has two sets of traveler wires running between it and a pair of threeway switches. There is no common wire nor is there a common terminal. The continuity test for a four-way switch requires a few extra steps. You need to put the clip on any pair of traveler screw terminals separately and then touch each of the other screws with the probe. This is a total of six tests for each position of the toggle (see the following figures). The test should show two continuous currents for each position of the toggle switch. (The paths between specific traveler screw terminals vary with different manufacturers.)

A four-way switch box has two cables with three conductors coming into it (thus four hot conductors or wires). Two are black; the other two are a second color, most likely red. When you replace the switch, be sure to match the wires to the correct traveler terminals. New four-way switches either match their terminals up by color (two are brass and two are copper), or the back of the switch might have wiring instructions. This makes your job easier. You simply have to match one color of wire insulation to one set of screws (red wires to brass screws, for example). See the following figures for a typical installation.

Three-Way Switch

Replacing a three-way switch is more involved than replacing a single-pole variety. Now you have traveler wires to deal with (these connect the two three-way switches) as well as the common wires.
This means the cable running between the switches is 12/3 (or 14/3) cable rather than the more common 12/2 (or 14/2).
Follow the same safety and testing procedures that you would with a single-pole switch. Because three way switches (and four-way switches) are more expensive than a common single-pole switch, you want to be certain that the switch is really broken before throwing it away and replacing it. When removing a three-way switch from its box, note to which terminal screws or
back-wired slots the wires are connected. Mark the common wire with a small piece of masking tape, or attach each wire to the new switch as you remove them from the old switch. The common terminal screw usually is copper; the traveler terminals are brass or sometimes silver. Note whether the neutral wire is being used as a hot conductor.

New Switches

The easiest switch to replace is the single-pole switch. Before popping in a new one—and this is true with any device—read the specifications on the old switch. These usually are listed on the metal mounting strap and include the following:

• The amperage and voltage ratings
• The type of current it will carry (AC only for house current)
• The type of wire that’s compatible with the device (CU for copper only, CO/ALR for copper or aluminum, ALR for aluminum only)
• Its Underwriters Laboratory or other testing service listing

The back of the device will indicate the acceptable wire gauge and a stripping gauge for measuring the amount of insulation to be removed prior to installation. The location of your switch will determine how its replacement gets wired. A switch can be at either the middle or the end of a run (one complete circuit). These positions in the run are simply defined:

• A middle-of-the-run switch can be anywhere between the beginning and the end of the circuit. There will be at least two cables entering the box (at a minimum, one on the line side coming from the panel and one leading to a fixture or other device).
• In an end-of-the-run switch (also referred to as a “switch loop”), the cable runs from the fixture to the switch. This requires special treatment of the white wire.

Remember to shut the power off at the service panel or fuse box and to test the switch with a voltage tester before removing the wires. Note the condition of the ends of the wires. You don’t want to reuse damaged or nicked wires. If you find any damage, cut off the minimum amount of wire necessary to remove this section and then strip off sufficient insulation (about 5/8 of an inch) so the wire will make a solid contact.

Continuity Coming Up

A continuity test will tell you whether a switch’s metal components, which are critical for the flow of the current, are intact or broken. A continuity tester is battery-powered and provides a current that passes from the tester’s clip through a device or fixture. The tester’s other component is a probe that lights up if a current is passing through the device as designed. To perform the test, a switch or fixture must be disconnected from its power source and removed. (The tester will supply the current for the test.) A continuity tester should never be used on a live current.
The following figures show you how to do a continuity test on a single-pole switch and a three-way switch. If your tests show you that the switch is the problem, it’s time to replace it.
If your tests show you that the switch is the problem, it’s time to replace it.

Checking the Devices

Switches, appliances, and fixtures test a bit differently than receptacles. The first three are tested for continuity and power and require both testing tools. A continuity tester will indicate whether the circuit’s pathway within the switch has any breaks in it from metal fatigue. It also checks other appliances and fixtures for similar breaks. Let’s start with testing for a switch.
Follow these steps to test a switch for power:

1. With the switch off, touch one of the voltage tester’s probes either to the bare end of the ground wire (the inside of the wire nut holding the neutral wires together) or, if it’s a metal box, to the side of the box.
2. Place the other probe against each black wire either at the terminal screw or at the back-wired slot.
3. The bulb should light up for at least one of the hot wires, the line wire coming from the panel or fuse box. If the tester does not light up for either black wire, the problem is somewhere in the circuit between the panel and the device. (Go to step 4 if it does light up.)
4. Turn the switch on and check the other black wire, which is the load conductor. If the bulb on the tester does not light up, the switch is bad and needs to be replaced.
5. If both black wires show current passing through them, recheck the fixture and the appliance because the problem is not with the switch.
6. Note: In some older homes with knob-and-tube wiring, the neutral wire has been switched and used as a “hot” conductor. This makes the task of troubleshooting much more difficult. If you have any questions or concerns while testing, call an electrician.

Probing the Problem

You flick the light switch and nothing happens. The coffeemaker, which was set on a timer to go off at 6 A.M., sits with pot of cold water on your kitchen counter. Before assuming that the devices are shot, follow this checklist:

1. Confirm that the circuit has power and that the fuse hasn’t burned out or the circuit breaker tripped.
2. Check to see if the appliance or fixture is working by checking light bulbs, cords, and plugs.
3. Inspect the connections at the fixture and at the terminal screws to ensure they are tight.
4. ❏ Check for a problem in the circuit itself.

The very first thing you should do is confirm that power is getting to the device. Every electrician has a story about going on a service call to repair a dead circuit only to discover that the breaker had tripped and no one checked. That’s a pretty expensive discovery for a homeowner. Your first step is to examine your fuse box or service panel. Does everything look okay? Are there burned-out fuses or tripped breakers for that circuit? Check carefully. Some breakers have very little sponginess and don’t move much when they trip. You might have to test several breakers if you haven’t done a circuit map and are uncertain which breaker controls the failed device. If you can eliminate the power source as the problem, check the connections (see the following figure) by taking the following steps:

1. Turn the power off.
2. Remove the cover plate from the device, and unscrew the device from the box.
3. See if the terminal screws are tight and have good contact with the wires.
4. If the device is back wired, there shouldn’t be any bare wire showing, only insulation.
5. Check the wire nuts or taped-and-soldered connections to be sure they’re tight.

If there are no problems with the connections, you’ll have to probe further with your handy voltage tester and a continuity tester.

Replacing Old Switches and Receptacles

Now that you know about switches and receptacles, it’s time to replace any that are broken or to upgrade existing ones. The most common upgrade is swapping a standard toggle switch for a dimmer. Newer, quieter models—that don’t have the resounding “click” of old switches—sometimes are installed in older homes that still have their original devices.
The most common reason for replacing a device is wear and tear. The clips in a receptacle that hold a plug tautly or the metal arm in a switch eventually can fatigue and no longer work properly. A simple loss of power to a fixture or an appliance, however, is not necessarily a reason to replace a device. You have to do a few system checks first, which we’ll discuss in this chapter.
The short projects in this chapter will help you get your feet wet—don’t take that literally, however, when working around electricity—and gain a degree of comfort with your electrical system. Three- and four-way switches require more troubleshooting skills, but we’ll cover the most common situations with both switches. We’ll also discuss upgrading your current two-wire receptacles and making them safer when the situation calls for it—without updating the entire system with a grounded conductor.