When choosing a multimeter, you first need to decide for what purposes it is purchased, and what types of work will be performed with it. Perhaps the cheapest analog device will do for you. And if you are going to be professionally engaged in electrical engineering, of course, instead of a simple digital device, you will need a multifunctional unit. Learn more about buying a multimeter below.
What criteria should be followed when choosing a multimeter?
Which device to purchase depends on what goals you are pursuing. In doing so, the following criteria should be taken into account:
- Convenience of work. This is the most important setting. All other criteria are not so important if you constantly experience inconvenience while working with the device. If the device is uncomfortable to hold, the readings are difficult to see, and the plug is difficult to get into the socket – the work begins to irritate.
- Functionality sufficient to solve your problems.
- Possibility to illuminate the display panel. An electrician often works with the lights off. Each time transferring the flashlight from the wires with the probes attached to the indicator and back is simply dangerous.
- The presence of a button for memorizing the measured value, which is very convenient – you do not have to write down or memorize readings.
- Moisture, dust and impact resistance. Measurements often have to be done in extreme conditions – in a damp basement or in a dusty attic, and dropping the device on a hard floor is often only a matter of time. If it has good security indicators, you don’t have to worry about exploitation. Protection is electrical and electronic. Electrical is just a fuse, but electronic protection is more reliable, and you don’t have to disassemble the device to replace the fuse.
- Reading accuracy is important, but not critical. Most work with a multimeter is simply a check for the presence / absence of contact or determining the health of the element.
- Brand. The de facto standard are the devices of the firms “UNI-T” and “Mastech”.
Expensive and complex multifunctional models are really necessary only for professionals – those who regularly perform responsible work with electrical equipment.
Selecting the safety category of the multimeter
An important point in the selection process is an accurate understanding of what voltages you will have to work with. In total there are 4 categories of electrical safety:
- “CAT I”- designed for low-voltage networks and standard office equipment (telephony, alarm, printers, copiers).
- “CAT II” – for intra-house networks with voltages up to 500 volts and for testing equipment designed for single-phase networks, including construction power tools and household appliances (hammer drills, washing machines).
- “CAT III” – for three-phase networks and three-phase equipment (household electricity meters, industrial machine engines, welding machines, single-phase lighting lines).
- “CAT IV”- for work with overhead power lines (power lines), underground cables, industrial electricity meters, transformer substations.
You should understand the difference between the electrical safety category of the multimeter and the rated voltage rating. The higher the safety category, the lower the risk of electrical injury, even if the device with category “CAT I” says “up to 1000 Volts”, and the device with category “CAT IV” says “up to 500 Volts”.
How to use one or another multimeter – read here.
Top multimeters – from home electrician to professional
Next, we offer you an overview of the most popular and reliable devices, among which you are invited to choose based on the use for which you need a multimeter.
Multimeter type “M812”
The easiest choice for home and garage is a multimeter like “M812“. It is quite small and light (about 90 grams), it is quite possible to put it in a shirt pocket. It can easily be kept in the tool box under the moped saddle. But, despite its modest size, it has all the necessary functions: a “ring” with sound, a voltmeter up to half a thousand volts (voltage is both constant and variable). As well as a built-in audio frequency generator to determine the performance of amplifiers.
Devices marked “DT-83*” (“M-83*”)
Suitable for beginner electricians. They have the necessary functions for measuring voltage, resistance, current strength, as well as sound “ringing” and checking semiconductor parts. Some additional functions available in other models of multimeters are not.
The disadvantage of this model is the lack of error protection. So when choosing the measurement mode, the incorrect position of the disk or the discrepancy between the current / voltage, the device may fail. But all minor shortcomings are redeemed by a very affordable price for the device.
Multimeter “DT266” (“C266”)
Such models are a logical development of the previous design. This is a semi-professional device, the capabilities of which are often enough for professionals. The main difference from its predecessors is the presence of a current-measuring “claw”, which allows you to measure the current parameters without direct contact with the conductor. Therefore, the weight of the apparatus, of course, is somewhat greater.
The kit necessarily includes a thermocouple to determine the temperature up to 750 degrees Celsius. Another plus is the button for fixing readings, while it is closed, the maximum value remains on the display.
However, many “266” models do not have the ability to determine the health of transistors and diodes (after all, this is more an electrical tool than electronics), so make a choice based on your needs.
“DT9208” and its modifications
They are perhaps the best in their price category up to 1000 rubles. The designers of this model clearly tried to create the most comfortable conditions for taking measurements:
- The scoreboard can be tilted “toward – away from yourself.”
- There is a special folding leg-stand so that you do not have to hold the device in your hands at an angle all the time so that you can see the readings.
- The perimeter of the case is covered with a soft and rough protective case of bright color, so that even in the dusk you can quickly find the device if, for example, it falls out of your hands.
- The marks on the case for the circular variator are painted in different colors to make it easier to navigate which mode is currently on.
- If there is no measurement for a long time, the device turns off automatically, saving energy.
- Button for holding readings during measurements.
- There is an additional fourth connector for the probe, taken out separately – for measuring the current strength of the order of milliamps.
- There are sockets for testing thyristors, diodes, capacitors and transistors.
- You can measure the logic level of the signal – for digital devices.
- Frequency meter from 2 kHz to 200 kHz.
- The temperature sensor is directly in the instrument case plus an external thermocouple.
Models like “MC 8229”
These are more professional multimeters that have all of the above advantages with the addition of the ability to measure:
- sound volume;
- air humidity.
Also, most professional multimeters have the following differences:
- can automatically select the measurement limit;
- have overload protection in all measurement modes;
- report overload by displaying “OL” (OverLoad) on the display panel;
- warn about incorrect connection of probes;
- have a display in several lines for comparing readings;
- warn of an imminent discharge of batteries;
- have an additional fuse with a self-recovery function.
What to choose from the range of Mastech?
branded Mastech many models are produced in the price range from $10 to $100. The company offers a full range of measuring instruments – from cheap and simple analog devices for those who are used to reading by the arrow, and to a stationary desktop model “Mastech MS8050”, which has laboratory measurement accuracy, software adjustment of measurements and the ability to transfer measurement results to a computer in real time.
For everyday tasks, a digital multimeter is quite suitable “DT830”, the price of which is about 3 US dollars. Its advantages are:
- overload protection;
- low battery indication;
- nests for testing semiconductor devices – transistors and diodes;
- warning label “NV” when measuring the maximum allowable voltage values.
Mastech also offers an interesting model of a light and convenient pen-type multimeter-probe.MS8211D»:
- miniature size and light weight;
- built-in overload protection;
- electrical safety category “CATII 600V»;
- automatic power off (after 15 minutes of inactivity);
- sound “ringing” of circuits;
- the ability to turn off / switch operating modes with the thumb of one hand;
- the tip of the probe on the body can be hidden inside by rotating the dielectric tip;
- the mode of storing the last and maximum of the measurements taken;
- durable carrying case with a Velcro flap and a special strap for attaching to a mounting strap;
- the crocodile connector is hidden inside the insulating tube.
In addition, this model is capable of checking the state of the signal of logic elements. Under the green plastic ring framing the tip of the probe, LEDs are lit: green – logical “0”, red – logical “1”.
In the video below, a professional electronics engineer explains the criteria for selecting a measuring instrument:
Choosing a multimeter is not an easy and responsible task, because you will work with it, possibly in dangerous and difficult conditions – in the dark, cramped, under high voltage. We hope that our article will help you make an informed decision and make the most accurate choice of measurement assistant!