When deciding on the best multimeter you need to seriously consider what your actual needs are before deciding on which model to purchase. There’s a wide range of multimeters available on the market but we’ve put together this practical multimeter buying guide to help you cut through the noise and choose the right model for your needs.
We review a range of multimeters from cheap to mid-range all the way up to professional-grade multimeters. There’s something here for the full range of needs and budget constraints.
Electricity is a basic part of everyday life, we all depend on it. Because we rely on electrical equipment for almost everything we do, it’s important that we keep everything working safely and properly. How do we do this when we can’t see what’s going on? The only way to check our electrical circuitry reliably is with an electrical measuring device. The most common instrument to do this is an electrical multimeter. Whether you use it for checking batteries, detecting faults with appliances, or problems with the wiring in your home, a multimeter is an indispensable item when it comes to diagnosing electrical faults.
We all take electricity for granted but problems can arise at any time. This might be that a circuit just stops working or it can be a fault that puts you at risk. For the homeowner, a cheap multimeter will help you to know what’s going on. This will not only help you ensure your safety but can also save you loads on the cost of calling in an electrician. A multimeter can help give you an idea of what the problem may be. Even if you’re not always able to repair it yourself, knowing the cause of the problem can help a lot.
Cheap Multimeter for DIY electrical troubleshooting | Etekcity MSR-C600
Cheap multimeters are great for basic troubleshooting, but not the most accurate and some may be limited when it comes to features. As you go up the price range, the multimeter will be better calibrated and therefore give a more accurate reading. This is essential for professionals who need better information to diagnose and repair more complex issues. For some, it’s okay to know what the voltage, current or resistance is within a reasonable margin. If you’re a professional electrician or technician, you’ll probably need more reliable data to do your job properly.
We’ve checked out a good variety of products, ranging from cheap multimeters for the basic DIY homeowner to more sophisticated models. We also recommend some in an intermediate price range – better suited for electronics enthusiasts. Finally, we’ve included a professional quality multimeter that is perfect for professionals or the more serious electronic hobbyist.
Best Cheap Multimeters
In this section, we’ll be looking at some of the best multimeters for the average guy. Generally, they’ll have many of the features that you’ll find on multimeters used by professionals, though they won’t take fine measurements as accurately. Cheap multimeters won’t detect small changes in voltage and if you’re measuring standard 120V household power, you’ll get a reading within a few volts of the true voltage. This is fine for checking the basics. After all, how many people really understand the finer details of electronics?
If you need to keep a multimeter around the home to do basic fault finding and measure batteries to see if they’re still okay, any of these multimeters will be perfect. They’re very reasonably priced and provide features that will give you the information that you need.
Later in the article, we’ll provide a basic guide to using a multimeter for those who aren’t so clued up about electricity. This will help you understand what all the multimeter features are used for and how to operate them. The aim is to give you a better understanding of what to look for and whether you’ll actually need to use all the features that a particular model provides.
Extech MN24-KIT | Best Cheap Multimeter
- MN24 – Manual Ranging CAT II-600V MiniTec and trade; MultiMeter with 7 functions including 1.5V and 9V Battery tests under load
- 40130 – Non-Contact Voltage Detector. Detects AC Voltage from 100VAC to 600VAC without touching the source
- ET15 – Receptacle Tester for detecting faulty wiring in 3-wire receptacles and five wiring faults
- Includes a practical storage case
Overview | Extech MN24-KIT
The Extech MN24 kit is ideal for the homeowner who might not have all the technical savvy to use all the complicated multimeter functions.
This multimeter is capable of measuring AC voltage up to 600V with two calibration settings – one for up to 200V (for normal US household power) and another setting for high-voltage current up to 600V, accurate within 1.5%. Measuring DC voltage has a greater range from 200mV up to 600V and is accurate within 0.5%. It also has a battery tester for 9V or 1.5V batteries. It allows for resistance testing from 200 OHMS up to 2000 Kilo-OHMS (accuracy within 0.8%). The Extech MN24 has a standard 10A fused ammeter function for DC only and is accurate within 1.8%. This multimeter also has a continuity tester with and audible tone for indicating an unbroken circuit.
Many less experienced people will prefer this kit because it comes with two basic, easy to use, additional testers. The AC voltage detector will show if there’s any voltage between 100V and 600V. The pen-shaped probe is very handy if you just need to see if there’s any AC electrical current present. It won’t give you a voltage reading but will only light up if it detects any AC voltage at the probe – very handy for a quick check to see if it’s safe to work on or around the area that you test.
The receptacle tester is another extra that many a home user will find to be very useful. It plugs into any standard US plug outlet and lets you know if your plug point or extension cord is connected correctly. So you can see if the ground, hot or neutral wires are connected to the correct pin before you connect it to the mains power.
The Extech MN24 will prove to be a useful kit to keep in any home. If you want to perform basic safety checks and determine whether your batteries are still usable, this multimeter kit will make it all very easy. Even if you’re more advanced in your electrical knowledge and want to check the resistance of heaters, speakers, electric motors or electronic circuitry, it will give you a reasonably accurate indication of what’s going on. A nicely priced, comprehensive kit for everyday use.
INNOVA 3320 | Digital Mulitmeter
- Auto-Ranging scales eliminate the need to dial in the correct range when making electronic measurements.
- 10 MegOhm input impedance for safe automotive use.
- Automotive uses include: automotive circuits, breakers, wiring, vehicle battery & charging systems, electrical components and more.
- Household uses include: outlets, fuses, wiring, general-purpose batteries, electronic hobbies and more.
- Large digital display.
- Single-setting resistance function for voltage (AC & DC)
- Color-coded LED’s display battery quick check
- Protective rubber corner guards for drop protection.
- Includes attachable test leads, holders and stand.
- Auto shut-off feature.
- U/L listed for safety and quality.
✓ View or download the MANUAL for the Innova 3320.
Overview | Innova 3320
This is a compact little multimeter and is designed with the novice in mind. Even with very little knowledge of electricity, you can use the Innova 3320 with confidence as it simplifies all tasks and has a couple of very handy automatic features.
The auto ranging dial means that you don’t have to know the voltage or resistance range when selecting what you want to measure. For detailed measurements, this isn’t too great but for most non-professional users this function is ideal. Most multimeters require that you need to select a particular setting close to the expected reading.
For example, if you’re measuring a standard vehicle DC circuit, you will select the voltage closest to 12V and not lower than this (usually this a 20V setting), this is so that the meter can accurately calibrate its reading for that range and provide a reading to the most accurate decimal position. The situation given is a pretty easy example, as most people know the voltage of a car battery. Sometimes, especially with resistance measurements, you may have no idea what the expected range is and this meter will set itself within the range that it detects. For people who are less familiar with electrical readings, this can help a lot.
Another very handy feature for general household use is the automatic battery load tester. You can choose which type of battery you’re testing (1.5V; 6V; 9V or 12V). Select the corresponding battery voltage with the dial and the meter will do a load test. One of the three LED battery lights will ignite. Basically, it tells you whether your battery condition is poor (needs replacing) with a red light, weak with a yellow light, or good with a green light.
Although small, it has a large LCD display that is easy to read. With all its functions operating with a single setting, it’s super easy to use. The Innova 3320 has a reasonable degree of accuracy and will serve the needs of most DIY users. It doesn’t require that you have any electrical knowledge beyond the absolute basics.
Etekcity MSR-C600 | Best Cheap Multimeter
- Autoranging clamp multimeter with AC current, AC/DC voltage, resistance, diode and continuity test
- Jaw opening measures AC current in a conductor up to 26mm without interrupting the circuit
- Features Data Hold, Max Reading and an easy-to-read large LCD
- Comes with a handy carrying pouch – Perfect for use while on the go
- Automatically enters sleep mode after 15 minutes of inactivity for energy conservation; 1-Year Warranty
Overview | Etekcity MSR-C600
It’s not often that you find a cheap multimeter that has a clamp fitting, so this one is a rare and great find. The advantage of a clamp is that you don’t need to strip the wires when testing load. If you want to measure the current that an appliance or circuit is drawing, you simply need to place the clamp around the hot wire and the electric field around the wire will give an amp reading. This is great for easily observing how much load you’re placing on a fuse or circuit breaker.
Because the ammeter works using a clamp there are only two input points for the probes, this is less confusing when connecting up the multimeter. It has auto range selection which also makes it ideal for less experienced users. Like most multimeters, the Etekcity MSR-C600 has a continuity tester with an audible beep to let you know that a fuse or wire is not broken.
Video | Etekcity MSR-C600 Clamp Multimeter
Apart from not having an automatic battery tester, this one compares fantastically to the other cheap multimeters that we’ve reviewed. I find the clamp ammeter to be a fantastic inclusion, that isn’t found on many that cost a lot more.
The multimeters in this section are of a reasonable quality standard and offer a level of accuracy that is acceptable when dealing with general wiring. If you’re an electrician that does not repair sophisticated electronics or any equipment that requires very accurate resistance or voltage readings, any these multimeters will be perfect.
For home users who want to do more than just check batteries and load, these will also be a better option. Any beginner in the electronics field will find these to be good enough for most of your testing requirements and you’ll get them at a more affordable price than the highly accurate professional meters.
Fluke 117 | Best Multimeter
True Electrician’s Multimeter
- VoltAlert technology for non-contact voltage detection
- AutoVolt automatic ac/dc voltage selection
- Low input impedance: helps prevent false readings due to ghost voltage
- Large white LED backlight to work in poorly lit areas
- True-rms for accurate measurements on non-linear loads
- Measures 10 A (20 A overload for 30-seconds)
- Resistance, continuity, frequency and capacitance
- Min/Max/Average with elapsed time to record signal fluctuations
- Compact ergonomic design for one-handed operation
- Compatible with optional magnetic hanger (ToolPak) for hands free operation
- CAT III 600 V safety rated
Overview | Fluke 117
Having worked for many years in the electronics industry, I know the value of a quality multimeter. In my opinion (you’ll find that most professionals agree with this), Fluke multimeters are as good as it gets. Anyone who works with electricity on a regular basis will probably be using a Fluke multimeter. They are very accurate and robust with a wide variety of models for specialized applications
The Fluke 117 is an entry level model and has been designed for general electricians dealing with standard wiring and basic electrical repairs. It has a standard AC voltage range up to 600V (accuracy of 1% for frequencies between 45Hz and 500Hz and 2% for frequencies higher than this). It measures AC millivolts with the same level of accuracy. DC voltage can be measured in millivolts or Volts (up to 600V) with an accuracy of 0.5%. It also has auto AC volt detection with an accuracy level of 2% for frequencies between 45Hz and 500Hz and 4% for higher frequencies. All AC voltage readings are true RMS.
Video | Fluke 117
Continuity testing has a 600Ω range, calibrated for a display within 1Ω. Resistance testing up to 6MΩ is accurate within 0.9% and up to 40MΩ within 5% accuracy. Diode testing uses a 2V charge with 0.9% accuracy. For current testing, the Fluke 117 can handle up to 10A with a 20A overload capacity for up to 30 sec, accuracy is 1.5% for AC frequencies between 45Hz and 500Hz, for DC current test accuracy is 1%.
The Fluke 117 is also able to measure frequency – Hz (V or A input)². It is able to measure up 999.99Hz with an accuracy level of 0.1%. I really like that it is also able to measure capacitance. Anyone who’s tried find faults on an induction motor will know how useful this can be. Eliminating a capacitor failure takes a lot of guesswork out of the equation and will save you time and frustration.
You can test any capacitor from 1nF up to 1000μF with an accuracy of 1.9% and from 1000μF to 9999μF with an accuracy of 5%. Another feature that you won’t find on many multimeters in this price range is a 33 segment bar graph that updates 32 times per second, this allows you to follow fluctuations in the unit that you’re measuring.
Along with these impressive specs and features, the Fluke 117 has an excellent safety feature, VoltAlert, which measures non-contact voltage. Surge protection is up to 6kV. There are also quite a number of Fluke accessories that you can get as optional extras, these include a number of heavy-duty cases, the i400S AC current clamp, temperature probes and quite a number of other items designed to make life easier for electricians.
For a really good multimeter with a high level of accuracy, as well as excellent features and accessories, the Fluke 117 gives you great value for money. As a top manufacturer of electrical testing equipment, quality is assured and it comes with a 3-year warranty.
- Maximum voltage between any terminal and earth ground : 600 V
- Surge protection : 6 kV peak per IEC 61010-1 600 V CAT III, Pollution Degree 2
- Fuse for A input : 11 A, 1000 V FAST Fuse (Fluke PN 803293)
- Display Digital : 6,000 counts, updates 4 per second
- Bar graph : 33 segments, updates 32 per second
- Operating Temperature : -10 °C to + 50 °C
- Storage Temperature : -40 °C to + 60 °C
- Battery type : 9 volt Alkaline, NEDA 1604A/ IEC 6LR61
- Battery Life : 400 hours typical, without backlight
Klein Tools MM3300 (69149) | Electrical Test Kit
Best Multimeter Kit
- The MM300 multimeter measures AC/DC voltage, DC current and resistance and has a safety rating of CAT III 600V, Class 2, Double insulation.
- The NCVT-1 has a bright green LED to indicate the tester is working; it changes to red and warning tones sound when voltage is detected.
- NCVT-1 has a digitally-controlled ON/OFF power button and auto power-off feature to conserve and extend battery life.
- Receptacle tester detects wiring configurations and indicates correct wiring, open ground, open hot, open neutral, hot/ground reversed; it does not indicate quality of ground, multiple hot wires, or a combination of defects.
- Includes visual and audible continuity indicators up to 25Ω.
- Includes test leads and batteries.
Overview | Klein Tools MM300
The Klein Tools MM300 (catalog no. 69149) is a very accurate multimeter that is intended for the general electrician and home user. Though it’s comparable to the Fluke 117 in terms of quality and accuracy, this one does not have any of the extra features and provides all the common functions that you’ll expect to find on a regular multimeter.
It is, however, designed to make life easier for general household electrical testing. To this end, the kit includes a probe tester for quick voltage detection and a receptacle tester for checking the connection of standard household plug outlets. If you don’t have the need to test capacitance or frequency, the Klein Tools MM300 may be preferable to the Fluke 117 in that it has these easy to use additional items.
You’ll find everything that you’d expect from a quality multimeter. It measures both AC and DC voltage up to 600V with AC calibrations for 200V and 600V, it allows for very accurate DC calibration from 200mV. DC current measurement is also well calibrated from 200μ up to a maximum of 10A. For testing resistance, it has settings from 200Ω to 2MΩ. It also has diode testing and continuity with an indicator up to 25Ω. A tester for both 1.5V and 9V batteries is also included in the range of features.
For its ease of use, the Klein Tools MM300 is an excellent option. The inclusion of quick testing instruments for basic tests and the battery tester will make this an ideal option for home users and electricians who focus mainly on domestic and light commercial electrical installation and repairs. Klein Tools is a respected manufacturer with over a hundred years of experience, so you can buy this product with complete confidence. It comes with a 2-year warranty.
Not many people using a multimeter will require the accuracy of a top grade piece of equipment. For engineers who need perfect accuracy under any working conditions, reliability is key to getting the desired results without wasting time or relying on guesswork, resulting from information that is not of the standard they require. For those of you who need a multimeter for working on sensitive electronics or high-end industrial equipment, there can be no better option than the Fluke 87V.
Fluke 87V | Best Multimeter
- Unique function for accurate voltage and frequency measurements on adjustable speed motor drives and other electrically noisy equipment
- Built-in thermometer conveniently allows you to take temperature readings without having to carry a separate instrument
- Optional magnetic hanger for easy set-up and viewing while freeing your hands for other tasks
- Large digit display with bright, two-level backlight makes the 87V significantly easier to read than older models
- True RMS AC voltage and current for accurate measurements on non linear signals
- Selectable filter for accurate voltage and frequency measurements on motor drives
- 0.05% DC accuracy
- 6000 counts, 3-3/4 digits
- 4-1/2 digit mode for precise measurements (20,000 counts)
- Measure up to 1000 VAC and DC
- Measure up to 10 A, 20 A for up to 30 seconds
- Built in thermometer lets you carry one less tool (TC probe included)
- Frequency to 200 kHz and % duty cycle
- Resistance, continuity and diode test
- 10,000 µF capacitance range for components and motor caps
- Min/Max-Average recording with Min/Max Alert to capture variations automatically
- Peak capture to record transients as fast as 250 µs
- Relative mode to remove test lead interference from low ohms measurements
- Auto and manual ranging for maximum flexibility
- Touch Hold to capture stable readings avoiding noisy signals
- Large display digits and two-level bright white backlight for increased visibility
- Analog bargraph for fast changing or unstable signals
- Input Alert provides audible warning against wrong use of input jacks
- Improved selectable sleep mode for long battery life
- Access door for fast battery changes without breaking the calibration seal
- “Classic” design with new removable holster with built in test lead and probe storage
- Lifetime warranty
✓ View or download the MANUAL for the Fluke 115 multimeter.
Overview | Fluke 87V
The Fluke 87V has been specifically designed for engineers who need to analyze complex signals and make decisions based on highly accurate information without wasting any time.
The Fluke low pass filter allows for incredibly accurate frequency measurements, measuring up to 200 kHz with an accuracy of 0.005%. This makes it the ideal instrument for working on adjustable speed drives. It also has the ability capture minimum and maximum peaks at a speed of up to 250μS.
The Fluke 87V is intended to give the most finely calibrated readings with incredible accuracy. It measures DC voltage from as low as 10μV up to 1000V with an accuracy of 0.05%. For AC voltage you can work from 0.1mV up to 1000V with a true RMS accuracy of 0.7% and the low pass filter operates up to 20 kHz (3db at 1 kHz). It measures both AC and DC current up to 10A with an overload capacity of 20A for 30 sec. Measuring DC current from as low as 0.01μA with an accuracy of 0.2%. AC current can be measured from a resolution of 0.1μA with a true RMS accuracy of 1%.
It has a resistance measuring capability of 50MΩ at a resolution of 0.1Ω and accuracy of 0.2%. Capacitance measurement is from 0.01nF up to 9.999μF. Frequency can be measured up to 200 kHz with increments of 0.01 Hz and an accuracy of 0.005%. Duty cycle measurements can be conducted up to 99.9% with a resolution of one decimal point (0.1%), this measurement will be accurate within 0.2% per kHz.
The Fluke 87V has a built-in temperature measurement ability. Measuring ambient temperature (without a probe) will allow for temperature readings from -328°F up to 1994°F. Using the 80 BK probe, you’ll be able to get a specific reading of between -40°F and 500°F. Accuracy for probe temperature measurements are within 2% or 2.2°C, depending on which is greater. Conductance can be measured up to 60.00nS within two decimal points and an accuracy of 1%. Diodes can be tested within a range of 3V with 1mV resolution and an accuracy of 2% (duty cycle accuracy 0.2% per kHz).
In-depth Video Review | Fluke 87V
Because environmental conditions can affect the accuracy of electronic measurements, it’s good to know that the Fluke 87V is able to work accurately under extreme conditions. Many industrial settings may require you to work at temperatures beyond the accuracy range of most multimeters. The Fluke 87V is designed to remain accurate at temperatures of -20°C-+55°C (-4°F-+131°) and humidity levels (without condensation) of 0%-90% for a temperature range of between 32°F-95°F and 0%-70% between 95°F and 131°F. All readings will be within their specified accuracy rating at an altitude of up to 2000M (6652 Ft).
The Fluke 87V is an incredibly versatile multimeter with a fantastic range of features and functions. In addition to the wide range of standard features, there’s an even greater selection of optional extras, this includes a number of current clamps, a fiber optic test kit, and many other options. A full list of accessories is available on their website.
After going through all these facts and figures, I’m sure you’ll agree that this multimeter is about the best you’ll get. Exceptional accuracy and the ability to make any of your required measurements with a very fine resolution, makes the Fluke 87V the best device for the professional who requires absolute reliability and accuracy under any conditions. What’s more, the Fluke 87V is covered by a lifetime warranty.
Learn more on the Fluke site.
How to Use A Multimeter
Depending on which multimeter you’re using, one can measure any parameter of electrical current. More advanced measurements, like frequency, require a better understanding of electricity. Using the more complicated multimeter features is for trained technicians and engineers who need this information for very specific purposes. In this guide to using a multimeter, we’ll focus on the basic features found on most multimeters. This is intended to give the home user and amateur electronics enthusiast an understanding of the most commonly used multimeter functions.
Video | Learn how to use a multimeter
A multimeter will always use a battery and your instruction manual will show you how to insert it correctly. Once you’ve inserted the battery, you’re ready to start using your multimeter. The buttons on a multimeter won’t all be the same but we’ll look at some of the common ones.
- Power – to switch the multimeter on or off. Most multimeters will switch off automatically if left unused for a certain period of time (usually around 15 min) to save the battery. If this happens, you’ll need to switch it back on when you want to resume using it.
- Hold – Use this button when you want to lock onto a certain reading and keep it displayed on the screen.
- Peak – If your multimeter has a peak function this can be very useful because most readings will fluctuate, electricity is not always stable. To get a reading of your peak level (for example maximum voltage) press and hold the peak button for a few seconds while taking the reading. The multimeter will record the highest level of that parameter for the period that the peak button is activated.
- Backlight – Most multimeters have a backlight for the LCD display, this makes it easier to read the information in poor light. Remember that this light consumes battery power, so to prolong your battery life, only switch it on when needed and switch it off when you’re done.
Connecting the probes correctly is important and using the wrong connection port will result in no reading or a false reading and can, in some cases harm the multimeter. Usually, a multimeter has three connection ports at the bottom of the meter. The center port is marked COM (common) and this port is always used. Strictly speaking, it doesn’t matter which color probe you use with a particular port but to keep things logical, we always plug the black probe into the COM port.
To the right of the COM port is the port used for voltage and resistance. The red probe will be used in this position for most functions. If your multimeter measures temperature or frequency, this will also be the port for these functions. To the left of the COM port is the current port. This port is only used when measuring amps.
Probably the most common use for a multimeter is to check if a battery or power supply is providing the correct voltage. You first need to select the correct current type (AC or DC). The AC range selector will be marked with VAC or V with a sine wave symbol directly below it. A sine wave is indicated by a line that curves in the shape of a wave. The DC range selector will be marked with VDC or V with the DC symbol directly below it. DC is represented by a solid line with broken line (dashes) below it.
Remember that you are always testing voltage with a live current. This means that if you touch the uninsulated tips of the probe when measuring high volts, you will get a shock. Also remember not to let the uninsulated tips of the probes to touch each other whilst connected to a live current, this will cause a short circuit which can harm the multimeter, yourself or the circuit that you’re testing.
If the multimeter has an auto-range function there will be no need to select a range, it will calibrate itself when it reads the voltage. Remember that auto-range will always be less accurate than selecting the range manually. The range selection for any measurement will depend on the multimeter, those with more range settings will be more accurate. You select the range for the closest value to the rated voltage for that application. Your range must always be higher than the expected reading. So if you’re measuring a 240V circuit and set the voltage range to 200, your reading will only be calibrated up to 199V maximum and this is the reading that you’ll get. You’ll need to select the next range that is closest to, but not lower than, 240V.
Having selected the correct voltage range, you’ll want to place the probes onto the positive and negative or hot and neutral wires in parallel. This means touching the tip of the probe to the corresponding conductor where it is exposed (not insulated). The black (COM) probe will always be connected to the neutral or negative wire, the red probe is connected to the positive or hot wire. If they are connected the other way around, you will read the voltage in reverse polarity.
You will get the same voltage reading, just with a minus sign at the beginning of the numeric value. If you connect the probes correctly and you get a negative reading, it means that the wires are not connected correctly (the polarity is reversed). When you get a negative reading, you should swap your positive and negative (hot and neutral for AC) connections to correct this.
The next setting that people will use a lot is for testing continuity, this is the same setting for testing a diode. Because this is a basic resistance test, the continuity/diode setting will usually be found in the resistance (Ω) range selection. It is marked with the diode symbol which is closed arrow tip pointing into a vertical line, this will be accompanied by the audio signal which looks like the WIFI signal that has been turned 90°.
Remember never to use continuity testing when there is current present, always disconnect the item that you’re testing from the power source. Failing to do this may cause damage to the multimeter or harm to yourself.
When you turn the selector to this position, the screen will display the number one, this indicates an open circuit meaning that there is no connection. If you touch the two probes together, you’ll hear a beep and the screen will display 0, this means that the circuit is closed. If you’re testing a diode it will give the resistance reading of the diode.
Testing for continuity has two basic purposes. One is to check if a conductor has been broken, like when a fuse has blown. The other use continuity is to check for a short circuit. When testing to see if a conductor is working properly place one probe on each end of the conductor, if it beeps and the screen displays zero, the conductor is fine. To check for a short circuit, place one probe on the positive (hot) and the other on the negative (neutral). If it beeps this means that there’s a short circuit. To check for ground leakage, place one probe onto the hot wire and one to the body of the appliance, a beep will indicate a leakage to ground. You should then follow the same procedure with the neutral wire.
Most cheap multimeters are only designed to test current for DC power. If you want to test the load of an AC circuit, make sure that your multimeter is designed for this. For this example, we’ll use the most common DC amp testing situation – testing if a car’s circuit is correct for the specified fuse. This can be handy if you’re connecting a trailer for the first time and want to know if the added load of the trailer wiring is not too much for that particular circuit.
You’ll need to change the red probe to the Amps port (usually to the left of the COM probe). Current load testing is always done in series, this means that you’ll connect your probes or alligator clamps inline along the positive conductor. This is usually easiest at the fuse box or across an open switch.
If you’re testing at the fuse box, remove the fuse for the circuit that you intend testing. Switch on the items connected to that circuit (e.g. lights). Set the Amp range selector to the closet setting for the fuse rating of that circuit. Then connect one probe to one end of the fuse holder and the other to opposite end of the fuse holder – in other words, you’re connecting your probes to the two points where the fuse makes contact. It doesn’t matter which probe you connect to which end of the fuse holder because you’re measuring in series. The meter will give you the reading in amps. Remember that every multimeter has a maximum amp rating (usually 10A). If you read a load higher than this, the ammeter’s internal fuse will switch the meter off. This often an electronic fuse that will automatically reset once you remove the load.
If you want to measure the load across a switch or circuit breaker, select the off position first. Then touch the probes to the points on either side of the switch. So, one probe connects to the wire coming into the switch and the other connects to the wire coming out of the switch.
If you’re using a clamp fitting, this is much easier. You simply place the clamp around the positive wire while the circuit is live. Your clamp should not touch the wire as the clamp measures the electromagnetic field (EMF) around the wire.
Probably the least common of household testing is resistance testing (ohms). However, if you’re working on electronics, you’ll often need to test resistors as they are very common items on PC boards. Resistance testing is also useful for checking resistance heaters and the windings of electric motors.
Before testing, the resistor has to be disconnected from the main circuit, otherwise you’ll be testing the resistance of the entire circuit – not just the item that you’re testing. If you’re testing an electronic resistor, this means using a soldering iron to remove the resistor and soldering it back when you’re done. If you’re testing a resistance heater, electric motor or speaker, remove the wires connected to it.
Once you’ve isolated the resistor, select the correct range. You’ll need to know the correct ohm rating for the resistor that you’re testing. The resistance range selector is marked with the ohm (Ω) symbol. Your probe connection to the multimeter will be the same port as the one used for voltage and continuity. You then connect one probe to one end of the resistor and the other probe to the other end of the resistor. You’ll be measuring this on a single line, so it’s not important which way around you connect the probes.
The meter will display a reading in ohms. If your reading is a value below one (0.1 or less) it means that your range setting is too high and you should turn the dial to the next setting that is lower than the one that you’re using until you get a reading that is above one. Once your reading is above one, you may still need to set your dial one position lower if you have a lot of numbers to the right of the decimal point. So if you get a reading of 1.45678, turning the dial to the next lower position will change it to 14.56 or close to this. You’ll find the reading at this setting will be calibrated more accurately for the reading that you’re taking – so it may look more like 14.345.