A voltage detector is made of plastic, so there is no direct contact with a circuit. This tester will indicate when voltage is present by sensing a magnetic field generated by a voltage. A voltage detector tests receptacles, cords, light sockets (results may vary), switches, and ballasts. This tester will only test for voltage on the 120 V part of a receptacle or cord (not neutral or ground). Always test on a known good circuit before use. Place the tip inside the 120 V side of a receptacle to see if power is on. Place the tip inside incandescent sockets and near fluorescent light sockets for presence of power (results may vary).
For testing receptacles including GFCIs. A test may be done to determine if power is present or if a receptacle is wired properly. It will show the status of the 120 V, neutral, and ground. This tester does not have a battery. The light pattern that indicates circuit condition can vary with different brands of testers.
GFCI test button (optional).
Pressing this button will trip a normally functioning GFCI and cut power to any receptacle that is connected to the load side of that GFCI. The GFCI test button will not work with old house wiring that does not have ground wires.
There are a variety of meters and testers available for testing electrical and electronic circuits. Test measurements include voltage, current, ohms, and continuity.
Light and/or beep indicates voltage used on 120 V side of receptacle only (not neutral or ground)
Detect if voltage is present on an electrical cord
Multimeters provides a measurement of volts (E), amps (I) and ohms (Ω). A multimeter can test receptacles, light sockets, electrical panels, fuses, and switches. A battery is used for continuity test. Even though a multimeter measures current (I), the measurement is limited to a fraction of an amp.
The older analog multimeter uses an indicator that moves over a printed range of E, I, and Ω. You can select maximum ranges of measurement on the meter depending on different ranges of E, I, and Ω that are going to be measured. One selector determines the type of measurement, while another selector determines maximum range. If measuring DC voltage, the red lead must be connected to the positive polarity of the voltage source, and the black lead to the negative.
A digital multimeter (DMM) provides a very precise measurement of E, I, and Ω, and has a digital display. This tester has a high input impedance which means you can measure low voltage on logic circuits. Some DMMs will have maximum ranges of measurement settings, others do not.
Clamp meters are usually multimeters that “clamp” around a wire to measure current (amps). A clamp meter can commonly measure up to 600 amps. A clamp meter can measure both AC and DC current. This meter can be used to measure the alternator current of your vehicle by clamping to a battery cable.
Test receptacles, lamp sockets, electrical panels, fuses, and switches. This tester has a low input impedance and places a small load on a circuit. It will not give precise voltage, but is a quick way to show if voltage is present. This tester can be used for certain photocells, dimmer switches, a poor connection, or parallel wires where voltage may be present, but not be able to operate a load. Certain models contain a battery for continuity test. See “solenoid tester warning” in the safety instructions above before using this tester.
A night light or hair dryer can test receptacles for the presence of voltage. A night light can be used to see if 120 V and neutral are present in a receptacle. A hair dryer can be used to test if a circuit could handle a very high current. If a nightlight works on a receptacle, but a hair dryer does not, there could be a loose connection or a bad receptacle or GFCI.
CAUTION! Before using any type of electrical meter or tester, follow these safety instructions. Not doing so may lead you to think the power is off when it is actually on, or give you a false measurement.
Select image to enlarge
Electrical Meters and Testers