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How to Troubleshoot Different Types of Electrical Light Switches

How to Troubleshoot Different Types of Electrical Light Switches


The switch is one of the most common and important electrical devices for lights. Usually, when electrical light switches fail, the light will not turn on. After determining that a light bulb is not burned out and a circuit breaker is not tripped, the switch may have failed. Here are some tips about how to troubleshoot light switch. 

Types of Electrical Light Switches

There are several different types of switches. Although they may look the same when they are installed with their faceplates intact, the various switches look and function differently on the inside. Before knowing how to troubleshoot light switch, we have to know better about electrical light switches firstly. 


Single-pole Switch

Single-pole switches are the most common universal switches. They can be used to control lights, sockets, and other devices from one site. One of main features that make single-pole switches different from three-way and four-way switches is that they have on and off marks on the toggle. But some style of single-pole switches do not have on and off markings, such as notably switches and rocker switches.

Single-pole switches have two brass-colored screw terminals which are attached to the hot, or power-sources, wires. These wires are often black. One brass terminal is designated for the incoming hot wire from the power source, and the other is for the hot wire into the fixture. Many single-pole electrical light switches also incorporate a ground terminal for connecting the circuit’s ground wire.

Normally, the neutral (usually white) wire is not connected to the switch. If two neutral wires exist in the box, then these wires typically are united so that they continue via the box without even touching the change. Or, you might observe just one impartial wire passing through the box. Sometimes, but you might observe a white wire connected to the switch, and that is if it’s working as a hot wire. In cases like this, the white wire should have a wrapping of tape on it close to the switch terminal to indicate the wire is functioning as a hot wire rather than a neutral wire. This may help you better know how to troubleshoot light switch.

Three-way Switch                                                                                                                                                                                                                                                                                                                                                                                    Three-way electrical light switches are always utilized in pairs and make it possible for users to control a light or receptacle in two distinct locations. These buttons don’t have any on/off mark because the off and on places will change as the buttons are utilized.

Three-way switches have three terminal screws. The hot wire from the power source joins to the darkest screw terminal marked "COM" for "common." Both of the other terminals are known as travelers and are synonymous. For purposes of security, it’s very important to keep in mind that travelers are almost always hot wires. Three-way electrical light switches also have a ground screw. 

The secret in replacing an aged three-way switch would be to indicate the cord attached to the COM terminal until you remove the old swap. Since both of the other terminals are synonymous, it’s not possible to get them wrong; they can go either way. When there’s a white cable attached to a traveler terminal, then it ought to be tagged with black tape to signify it’s hot.

Three-way switches are often found at the ends of a staircase, in garages or basements which have two entrances, in halls, and other areas where two individual electrical light switches control a single light.

Four-way Switch

Four-way switches are used between two three-way switches to offer hands for an outlet or light fixture out of three or more different places. If you wish control from over three places - for instance, five places - you’d still use two three-way switches (one on each end) and three four-way switches between the two three-way switches.

Four-way switches appear somewhat like double-pole switches, but they don’t have any on/off markings. They have four terminals and a ground terminal. The four terminals are often brass-colored. There’s no "COM" or "common" terminal which can be found on three-way switches. Four-way switches serve as switching devices for traveler wires between the three-way switches.

While not generally utilized, four-way electrical light switches are occasionally found in long halls and in very large rooms that have over two entrances.

How to Troubleshoot Light Switch 

Then we will see how to troubleshoot light switch.

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Single-pole Switch

1. With power on, remove the cover in the switch and turn the switch off. Using a voltage detector, place it next to the terminals on the switch. See if there is a voltage in one of these switch terminals. In case the tester detects voltage, turn the switch on and see whether the voltage is detected at the other switch terminal.

2. One terminal (line) will constantly have voltage and another will possess voltage only when the switch is still on. If you only detect voltage at one terminal once the switch is toggled, the switch has likely neglected. At times the terminals of electrical light switches are connected to the rear of the switch, and voltage cannot be detected while the change is inside the electrical box.

3. Turn off power to the switch at the circuit breaker. The switch wires don’t need to be disconnected at the moment. Using a continuity tester on the terminals, see whether there’s continuity when the switch is switched on. When there is no continuity, the switch has failed and has to be replaced.

Three-way Switch

1. Make sure the power is off. Remove the two 3-way electrical light switches so you can access the switch terminals. The wire connections do not have to be removed.

2.Using a continuity tester, check continuity between the common (black) terminal and each of the traveler terminals (brass-colored) of each 3-way switch.

3.There should be continuity between the common terminal and only one of the traveler terminals. After toggling the switch, there should be continuity between the common terminal and only the other traveler terminal.

When a 3-way switch fails, there will usually be no continuity between the common terminal and one (sometimes both) traveler terminals of one of the 3-way electrical light switches

Four-way Switches

The steps about how to troubleshoot light switch in four-way switching structures can be familiar to that for three-way switches.

1. Switch off electricity to the switches in the circuit breaker. Eliminate each the buttons so that you may get into the switch terminals. The cable connections don't need to be eliminated.

2. Practice the steps the above mentioned to test there-ways.

3. There needs to be continuity between the initial black terminal and just among those brass terminals.

4. After toggling the change, check continuity between another black terminal and every one of those brass-colored terminals. There needs to be continuity only between the black terminal along with the brass terminal which didn’t show continuity instep 3.

When four-way electrical light switches fail, there will usually be no continuity in step 3 or step 4.

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