How to Test for Voltage

Before you begin any do-it-yourself job that requires you to work with or around electricity, it is best to turn the electric off. This is important for both safety and equipment issues. But in many homes the electric panels may not be properly labeled, and assuming you turned off the right breaker is a mistake waiting to happen. In order to be absolutely certain you turned off the right breaker, you have to test the circuit for voltage. Here is how to test for voltage.

Difficulty: Easy

Instructions

Things You'll Need:

• Voltage tester

1. Figure out which circuit you are going to be working on. Turn off the breaker that you believe is delivering the power to it. For a wall receptacle, many people will just plug a lamp into the outlet to see if the line is still hot. This is unreliable because if the bulb is blown, you may still be dealing with a live circuit. Always use a voltage tester to check for power.

2. Next, there are a number of different voltage testers available on today's market. Which one you prefer to use is up to you. If you are not well-versed in dealing with electricity, then I would recommend avoiding the multimeters that can be found in hardware supply stores. Multimeters feature multiple applications like testing for voltage, resistance and amperage. To keep matters simple, stick with a voltage-only tester.

3. 
   Wiggly voltage tester

   The image you see here is a traditional voltage tester. The two leads get inserted into the two slots on a regular outlet (one lead in each slot). If the outlet is still hot, then the voltage indicator on the unit will notify you. If you have an outlet or switch already removed from the wall, then one lead will be placed on one of the "hot" terminals and the other lead gets placed on one of the "neutral" terminals. If you test it and nothing happens, the line is dead--but always double-check the work ability of your tester by testing it in an outlet you know to be hot before assuming the circuit is off! The cost for this tester is in the $20 to $30 range.

4. 
   Basic voltage tester

   This type of voltage tester is similar to the one above it, but it is a more basic version. It also features two leads, but with this tester, if voltage is present, there are lights that will illuminate to notify you.

5. 
   No-Contact voltage tester

   The voltage tester you see here is called a "no-contact" voltage tester. It features a thin tip that fits easily in the slot on the front of a receptacle. When voltage is detected, the tip will illuminate and some models will alert you by audio as well. It is called "no-contact" because it does not have to touch the actual terminals on the electric component in order to read voltage. You can simply touch the tester's tip to a wire and it will notify you of voltage. The one drawback with this tester is that it is very sensitive, so if you have more than one circuit in a box, it may pick up on the voltage running through the other wires, even though the circuit you are concerned about is off.

6. Another type of voltage tester that works great for the do-it-yourselfer is the plug-type voltage tester. It resembles a regular plug and all you have to do is plug it in to a receptacle. There are a series of lights on the tester that will indicate if there is voltage detected. But these testers will also tell you much more. For instance, depending on which lights on the tester light up, you may determine that you have lost the neutral, the outlet may not be grounded properly or the wires may be reversed. The only downfall about this voltage tester is that it is only used for testing receptacles.

7. This is an area that can get quite involved as far as voltages go, but for the do-it-yourselfer, checking for voltage is a fact of whether the circuit is active or not. If you use a digital voltage tester and you notice a fluctuation in voltage or you get a reading above or below your normal house voltage, you should call in an experienced electrician immediately.

Tips & Warnings

• Always check your voltage tester in a working outlet to ensure that the voltage tester is working properly.
• If you are using a voltage tester with a digital readout, replace the batteries every 6 months.
• Store your voltage testers in a dry location away from severe temperature changes.
• Avoid testing for voltage in a wet location.
• When working with exposed wires, always keep the wires separated.