How to Use a Multimeter
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1: How to test batteries
Test battery life using a multimeter or volt-ohm meter (VOM). Analog-type multimeters use a needle and printed scales to display results from a variety of electrical tests.
Function setting: Direct current (DC) voltage
Scale setting: 12 volts
Test probes: Match the polarity (“+†to “+†and “-†to “-â€) of the test probes and the battery.
Good reading: 6 volts (this battery's original rating)
Bad reading: Batteries with voltage readings 20 percent below their original rating should be replaced.
A multimeter is a black box of electronic circuitry that allows you to troubleshoot just about any type of electrical wiring or device. You simply dial the proper function and scale, touch the two test leads to the wiring or device in question and check the meter reading. Depending on the setting, the multimeter will tell if you have a broken connection, no power, poor connections, faulty parts and more.
With all its numbers, dials and switches, a multimeter (also known as a volt-ohm meter, or VOM) can be pretty intimidating. Yet it's well worth learning, is relatively inexpensive and should be in the toolbox of anyone seeking to do wiring diagnostics and appliance repair. Here, we'll walk you through the basics and show you six quick, down-to-earth tests you can safely use today.
Multimeter Terms
It's hard to visualize electricity, so I've always thought of it like a river. In a river, there's a certain volume of water (similar to electrical amperage, or amps) flowing with a certain potential force (like voltage) that encounters obstructions as it flows (resistance measured in ohms). Hold that big picture in your mind, then add these key concepts about both electricity and VOMs:
Alternating current (AC) voltage: The type of electricity that powers your house.
Direct current (DC) voltage: The type found in auto and household batteries.
Resistance (measured in ohms): The lower the reading, the easier electrical current (measured in amps) flows through circuit material.
An open circuit equals trouble: There is high resistance from a broken connection, a faulty part or a switch that's been turned off. There isn't a complete circuit path and no current will flow.
A closed circuit is good: It means a minimum of resistance is present because a connection or part is working. Note: Check the pathways in the wiring or device being tested for any random loose wiring that's touching the circuit you're testing. Sometimes a broken connection (“short circuitâ€) can look like a closed circuit. Short circuits can harm you, destroy equipment and start fires.
Continuity testing determines if an open, shorted or closed circuit exists in an appliance, electrical or electronic device and is a common use for multimeters.
On a VOM, infinity signifies an open circuit. On an analog multimeter, infinity shows up as an unwavering needle that won't move off the far left side on the display. On a digital multimeter, infinity reads “0.L.â€
On a VOM, “zero†means a closed circuit has been detected. The display needle moves to the far right side of an analog scale; “zero†reads “0.00†on a digital VOM.
Selecting the proper range is very important and refers to setting the function switch on your multimeter to a voltage or amperage value that's higher than the top value you anticipate testing. Digital multimeters have a nifty feature, auto-ranging, that automatically selects the widest possible range once you set the function switch for ohms, current and voltage (AC or DC). Auto-ranging gives you the safest testing capacity each time you change back and forth from, say, measuring resistance to voltage readings.
Testing a broken extension cord
Check for a broken wire or bad plug connection in an extension cord by bending the cord along its length.
Function setting: Ohms.
Scale setting: Auto-ranging.
Test probes: Connect the prongs together at one end of the cord with a jumper wire, creating a closed circuit. Insert the testing probes in the other end to complete the circuit, and then turn on the multimeter. Don't forget a second test to check along the safety ground wire too.
Good reading: A “0.00†reading would indicate “zeroâ€â€”a closed circuit.
Bad reading: This “0.L.†reading indicates “infinityâ€â€”an open circuit. This cord has a broken wire or loose connection.
Caution!
Before running a resistance test, avoid possible injury to yourself and damage to the multimeter by disconnecting power to appliances and shutting off circuits.
free upload pictures
1: How to test batteries
Test battery life using a multimeter or volt-ohm meter (VOM). Analog-type multimeters use a needle and printed scales to display results from a variety of electrical tests.
Function setting: Direct current (DC) voltage
Scale setting: 12 volts
Test probes: Match the polarity (“+†to “+†and “-†to “-â€) of the test probes and the battery.
Good reading: 6 volts (this battery's original rating)
Bad reading: Batteries with voltage readings 20 percent below their original rating should be replaced.
A multimeter is a black box of electronic circuitry that allows you to troubleshoot just about any type of electrical wiring or device. You simply dial the proper function and scale, touch the two test leads to the wiring or device in question and check the meter reading. Depending on the setting, the multimeter will tell if you have a broken connection, no power, poor connections, faulty parts and more.
With all its numbers, dials and switches, a multimeter (also known as a volt-ohm meter, or VOM) can be pretty intimidating. Yet it's well worth learning, is relatively inexpensive and should be in the toolbox of anyone seeking to do wiring diagnostics and appliance repair. Here, we'll walk you through the basics and show you six quick, down-to-earth tests you can safely use today.
Multimeter Terms
It's hard to visualize electricity, so I've always thought of it like a river. In a river, there's a certain volume of water (similar to electrical amperage, or amps) flowing with a certain potential force (like voltage) that encounters obstructions as it flows (resistance measured in ohms). Hold that big picture in your mind, then add these key concepts about both electricity and VOMs:
Alternating current (AC) voltage: The type of electricity that powers your house.
Direct current (DC) voltage: The type found in auto and household batteries.
Resistance (measured in ohms): The lower the reading, the easier electrical current (measured in amps) flows through circuit material.
An open circuit equals trouble: There is high resistance from a broken connection, a faulty part or a switch that's been turned off. There isn't a complete circuit path and no current will flow.
A closed circuit is good: It means a minimum of resistance is present because a connection or part is working. Note: Check the pathways in the wiring or device being tested for any random loose wiring that's touching the circuit you're testing. Sometimes a broken connection (“short circuitâ€) can look like a closed circuit. Short circuits can harm you, destroy equipment and start fires.
Continuity testing determines if an open, shorted or closed circuit exists in an appliance, electrical or electronic device and is a common use for multimeters.
On a VOM, infinity signifies an open circuit. On an analog multimeter, infinity shows up as an unwavering needle that won't move off the far left side on the display. On a digital multimeter, infinity reads “0.L.â€
On a VOM, “zero†means a closed circuit has been detected. The display needle moves to the far right side of an analog scale; “zero†reads “0.00†on a digital VOM.
Selecting the proper range is very important and refers to setting the function switch on your multimeter to a voltage or amperage value that's higher than the top value you anticipate testing. Digital multimeters have a nifty feature, auto-ranging, that automatically selects the widest possible range once you set the function switch for ohms, current and voltage (AC or DC). Auto-ranging gives you the safest testing capacity each time you change back and forth from, say, measuring resistance to voltage readings.
Testing a broken extension cord
Check for a broken wire or bad plug connection in an extension cord by bending the cord along its length.
Function setting: Ohms.
Scale setting: Auto-ranging.
Test probes: Connect the prongs together at one end of the cord with a jumper wire, creating a closed circuit. Insert the testing probes in the other end to complete the circuit, and then turn on the multimeter. Don't forget a second test to check along the safety ground wire too.
Good reading: A “0.00†reading would indicate “zeroâ€â€”a closed circuit.
Bad reading: This “0.L.†reading indicates “infinityâ€â€”an open circuit. This cord has a broken wire or loose connection.
Caution!
Before running a resistance test, avoid possible injury to yourself and damage to the multimeter by disconnecting power to appliances and shutting off circuits.
